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Cell walls were prepared from parental and filamentous cells of Streptococcus cremoris HP. In addition to aspartic acid, glutamic acid, alanine, and lysine in a 1:2:3:1 ratio, such preparations contained hot formamide-extractable material composed of glucosamine, glucosa-mine-6-phosphate, glucose, galactose, and rhamnose. Parental and filamentous cell walls contained, respectively, 210 and 225 disaccharide units per milligram. The ratio of muramic acid: peptide subunits was about 1.3 for both preparations.Enzymic and chemical analyses revealed that glycan strands are incompletely substituted, peptide cross-bridging is not mediated by D-alanyl-L-alanyl linkages, peptide subunits are linked together to form large moieties, and no significant differences in peptidoglycan structure exist between parental and filamentous cell walls.Analysis by dinitrophenylation techniques disclosed the presence of significant quantities of glucosamine and muramic acid residues with free amino groups in the peptidoglycans of both cell wall preparations. Conversion of such groups by dinitrophenylation or N-acetylation greatly enhanced the response of cell walls to lysozyme digestion.

Activities of glucose 6-phosphate, 6-phosphogluconate, and isocitrate dehydrogenases, together with intermediate levels of the glycolytic pathway and the pentose phosphate cycle, were measured throughout a year in the living bark of poplar ( Populus gelrica ). Shoots, immediately after budding (early May), contained very high levels of the three enzyme activities, which fell gradually by early or mid-July to a level, roughly equivalent to budding (May) or growing (July) 2-year-old twigs. In September, the former two dehydrogenase activities of the new shoots and 2-year-old twigs began to rise, while the latter activity started to decrease. The rise of the two dehydrogenase activities continued until late November (or early December). The high level of the two dehydrogenase activities lasted until early in April of the following year and then the decrease in the activities began prior to the onset of budding, reaching a low, basal level in early May. The profile of changes in the two dehydrogenase activities appeared to coincide with the increase and decrease of soluble proteins. Normal concentrations of total hexose phosphates in the glycolytic pathway plus 6-phosphogluconate were found to be 288 to 895 μmoles/kilogram dry weight. During the metabolism transition (September and April), a transient and striking increase of 6-phosphogluconate was observed. In September, 6-phosphogluconate reached a level on the order of 10 −4 m and was 4 times that of fructose 6-phosphate. The increase in 6-phosphogluconate coincided with the increase in the glucose 6-phosphate dehydrogenase activity. Coincidentally, with the change of 6-phosphogluconate level, a large deviation of the in vivo ratio of fructose 6-phosphate to glucose 6-phosphate from the known equilibrium constant was observed, showing the relation of pentose phosphate cycle enzyme activity to the control of glycolysis. The ratio of glucose 6-phosphate to glucose 1-phosphate deviated from that predicted. These ratios fluctuated throughout the year and were affected by the growth phases. The levels of pentose phosphate cycle metabolites, except for 6-phosphogluconate, in the bark were extremely low. The level of inorganic phosphate in the living bark throughout the year was dependent upon the growth phases, suggesting the presence of a regulatory mechanism to maintain inorganic phosphate at a given level as the growth phase changed. Sugar phosphate levels of popular twigs or potato tubers ( Solanum tuberosum ) remained constant after they were stored for 2 weeks at low temperatures, whereas in sweet potato roots ( Ipomoea batatas ), the level rose to about 9-fold of the control, indicating the presence of a strict regulatory system for the synthesis and catabolism of sugar phosphate in the former two.

Summary 3-deoxy-D-arabino-heptulosonate-7-phosphate synthetase (E.C.4.1.2.15), the first enzyme of the aromatic amino acid biosynthetic pathway, has been studied in a Mycobacterium phlei strain, cultivated in a minimal salt medium, either as surface grown cells (conditions I) or as shaken medium cultures (conditions II). Conditions I were retained to obtain a 14-fold purified fraction subsequently used for the study of the enzymatic activity. An optimum pH at about 6.6 is observed. Co++ is essential for activity and Zn++ is a strong inhibitor. The Km value is 3.5 mM for phosphoenolpyruvate and 0.45 mM for erythrose-4-phosphate. Under conditions I, each aromatic amino acid inhibits weakly the activity, while under conditions II a higher inhibition was observed with L-tyrosine and L-phenylalanine. Under both conditions, a synergistic inhibitory effect is observed with the three aromatic amino acids together, with a maximum effect around 0.1 mM for each amino acid under conditions I and 0.01 mM under conditions II. A similar synergistic effect is also obtained with the two tryptophan containing pairs, and the inhibition attained is nearly equal to the maximal inhibition observed when the three aromatic amino acids are present (about 75 p. cent of total activity). L-phenylalanine plus L-tyrosine have only a slight synergistic effect, highly enhanced by the addition of L-tryptophan. From the synergistic inhibition characteristics of the enzyme joined to the fact that subsequent fractionation procedures failed to separate different DAHP-synthetase activities, it is concluded that M. phlei contains a single DAHP-synthetase, with a molecular weight of about 130,000, as determined by gel filtration and sucrose density gradient.

The concentrations of fructose diphosphate, dihydroxyacetonephosphate, pyruvate, lactate, glycerol-3-phosphate and proline in the thorax of the resting tsetse fly Glossina morsitans are assayed and the contribution of glycolysis to the provision of energy in the tsetse fly is discussed.

Electron spin resonance has been used for the identification of the radicals in the gamma-irradiated single crystal of deoxycytidine 5′-monophosphate monohydrate. From the number and angular dependence of the proton couplings the =C(4′)—Ċ(5′)—H2(5′) radicals have been identified. These radicals are formed by the breakage of the sugar—phosphate bond.

Nuclear membranes show specificity toward the transport of different compounds. Under experimental conditions we found that 2,4-dinitrophenol was not transported into isolated nuclei while maleate and succinate were taken up by isolated nuclei. Our data indicate that the nucleus uses an energy-dependent system to accumulate oxidative substrates such as succinate. We found that carnitine was taken up by isolated nuclei and also stimulated the nuclear uptake of succinate while DNP, maleate, and malonate inhibited nuclear uptake of succinate. Pyruvate and fructose-1,6-diphosphate were taken up very readily by isolated nuclei but antipyrine did not show significant nuclear penetration. We have concluded that nuclear membranes of isolated nuclei from calf thymus are highly selective as indicated by the uptake of some oxidative phosphorylative substrates such as succinate and pyruvate, and some sugar phosphates such as fructose-1,6-diphosphate.

A chromatographic procedure has been described using a new automated detection system that allows separation at the 10 nmole level of all the glycolytic intermediates as well as AMP, ADP, and ATP in pure samples and samples of skeletal muscle and blood. Separations are carried out on 3 × 500 mm columns packed with modern anion exchange resins of closely sized, fine particles and a linear gradient of ammonium chloride containing borate in order to complex the sugar phosphates. Pressures are moderate, and elutions are complete within 5–8 hr with excellent reproducibility and recovery of each compound. Screening runs can be made in only 90 min with shorter columns and with some sacrifice in resolution for certain compounds.

d-Arabinose-5-phosphate andd-sedoheptulose-7-phosphate were found to be substrates, although not inducers, of the hexose phosphate transport system ofSalmonella typhimurium. Transport of these two sugar phosphates by wild-type strains required preinduction of the hexose phosphate transport system. A mutant ofS. typhimuriumconstitutive for this system also transportedd-arabinose-5-phosphate andd-sedoheptulose-7-phosphate in a constitutive fashion. Glucose-6-phosphate was a potent competitor of the transport of bothd-arabinose-5-phosphate andd-sedoheptulose-7-phosphate. TheKmvalues for transport ofd-glucose-6-phosphate,d-arabinose-5-phosphate, andd-sedoheptulose-7-phosphate were 0.13, 0.32 and 1.61 mM, respectively. The apparentVmaxvalues for transport ofd-glucose-6-phosphate,d-arabinose-5-phosphate, andd-sedoheptulose-7-phosphate were 6.3, 13.2 and 3.0 nmol per min per 5 × 108bacteria, respectively.d-Ribulose-5-phosphate andd-xylulose-5-phosphate did not inhibit transport of the above substrates, whereasd-ribose-5-phosphate was a weak inhibitor ofd-sedoheptulose-7-phosphate transport.

The results of a CNDO/2 all-valence electron crystal orbital study are reported for the sugar-phosphate chain of DNA. The valence and conduction bandwidths are found to be large enough to make electronic delocalization through this backbone possible. Different mechanisms for charge carrier transport in DNA are compared on the basis of the electron and hole effective masses. Conduction along the backbone seems to be at least as probable as through the aperiodic system of the superimposed nucleotide bases.

The primary route of CO2 incorporation in C-4 plants (corn) has been formulated to be β-carboxylation catalyzed by phosphoenolpyruvate carboxylase, while in C-3 plants (spinach) CO2 enters the carboxyl carbon of glycerate 3-phosphate after reacting with ribulose 1,5-diphosphate. Detached leaf tissues of spinach and corn were compared with respect to their fixation of CO2 in the dark or in the light subsequent to illumination in the absence of CO2 in order to accumulate the primary compound for carboxylation. Prior illumination of corn and spinach leaves in an atmosphere of N2 containing 1.5% O2, enhanced dark 14CO2 fixation 15- to 25-fold over that of unilluminated leaves. In corn the primary products (80%) of enhanced dark fixation were malate and aspartate. Less than 5% of the incorporated 14CO2 appeared in glycerate 3-phosphate and other intermediates of the reductive pentose phosphate cycle. In spinach, roughly one-half of the isotope was found in glycerate 3-phosphate and sugar phosphates with about 25% in alanine. The levels of ribulose 1,5-diphosphate, glycerate 3-phosphate, and phosphoenolpyruvate were determined during preillumination under an atmosphere containing N2 and 1.5% O2, after pulses of CO2 either in a light or in a dark period. In both tissues ribulose 1,5-diphosphate increased linearly during preillumination and decreased rapidly following the introduction of CO2. Glycerate 3-phosphate was little affected during preillumination but increased rapidly upon addition of CO2. In both species the level of phosphoenolpyruvate was essentially unchanged during preillumination but increased sharply in corn leaves with introduction of CO2. CO2 pulses had no effect on the level of phosphoenolpyruvate in spinach leaves. It was concluded that ribulose 1,5-diphosphate can serve as a primary acceptor of CO2 in detached leaves of C-4 (corn) and C-3 plants (spinach).

Fructose diphosphatase of Hydrogenomonas eutropha H 16, produced during autotrophic growth, was purified 247-fold from extracts of cells. The molecular weight of the enzyme was estimated to be 170,000. The enzyme showed a pH optimum of 8.5 in both crude extracts and purified preparation. The shape of the pH curve was not changed in the presence of ethylenediaminetetraacetic acid. The enzyme required Mg 2+ for activity. The MgCl 2 saturation curve was sigmoidal and the degree of positive cooperativity increased at lower fructose diphosphate concentrations. Mn 2+ can replace Mg 2+ , but maximal activity was lower than that observed with Mg 2+ and the optimal concentration range was narrow. The fructose diphosphate curve was also sigmoidal. The purified enzyme also hydrolyzed sedoheptulose diphosphate but at a much lower rate than fructose diphosphate. The enzyme was not inhibited by adenosine 5′-monophosphate but was inhibited by ribulose 5-phosphate and adenosine 5′-triphosphate. Adenosine 5′-triphosphate did not affect the degree of cooperativity among the sites for fructose diphosphate. The inhibition by adenosine 5′-triphosphate was mixed and by ribulose 5-phosphate was noncompetitive. An attempt was made to correlate the properties of fructose diphosphatase from H. eutropha with its physiological role during autotrophic growth.

Absorption and metabolic fate of 14C-glucose after injection into mid-gut preparations from Locusta migratoria were studied in vitro. After 5 min nearly half of the total radioactivity had already passed into the incubation medium and in 2 hr there was an increase to 75 per cent. The radioactivity in the medium was found mainly in glucose and fructose, which were approximately equally labelled, and a minor part appeared in the organic acid and sugar phosphate fraction. This pattern of labelling changed drastically when non-radio active glucose was present in the incubation mixture. In these experiments an extensive synthesis of sucrose could be demonstrated. Sucrose formation from UDP-14C-glucose by mid-gut homogenates was stimulated by fructose-6-phosphate. The appearance of radioactivity in the contents of the gut and in the faeces was demonstrated in in vivo experiments after injection of 14C-glucose into the haemolymph. Sugar concentrations in the haemolymph of locusts were measured after 24 hr starvation and after feeding. The levels of glucose, fructose, and sucrose were very low in the starving animals and increased ten- to twenty-fold after feeding. The trehalose concentrations remained high and relatively constant. The activities of 18 enzymes of the intermediary metabolism were assayed in the fore-, mid-, and hindgut.

The mechanism of the radiation-induced dephosphorylation reaction was investigated by studying the γ-radiolysis of 10m M solutions of D -glucopyranosyl phosphate, D -glucose 6-phosphate (Glc-6-P), and d -ribose 5-phosphate (Rib-5-P). Dephosphorylation occurred with OH-radical participation, since G(H 3 PO 4 ) values for nitrous oxide-saturated solutions were 4.1, 1.7, and 2.3, and for nitrogen-saturated solutions 2.6, 1.1, and 1.6, respectively. The formation of phosphate-free compounds accompanied the release of inorganic phosphate. The main, neutral products of the radiolysis of Glc-6-P were 6-deoxyhexos-5-ulose (G = 0.2) and D - gluco -hexodialdose (G = 0.3). Irradiation of Rib-5-P gave ribo -pentodialdose and 5-deoxypentos-4-ulose as the main, neutral products. A scheme for the dephosphorylation process is proposed.

The respiratory responses of substrate-depleted excised root tips to a range of sugars, sugar phosphates, and sugar alcohols have been determined by measuring oxygen uptake by the direct method of Warburg. Sucrose, dextrose, and laevulose are the only sugars which promote a high level of oxygen uptake. The effects of azide and DNP on the oxygen uptake promoted by sucrose and by dextrose are described. Mannose is a strong inhibitor of respiration. This inhibition is reversed by the simultaneous addition of those sugars which also reverse the growth inhibition caused by mannose. Mannose inhibits the respiration of sucrose and of glycolytic intermediates. Galactose is slowly respired and does not, even at high concentration, inhibit the respiration of sucrose. The results are discussed in relation to the growth effects of the sugars tested.

The absorption and initial metabolism of glucose by the acanthocephalan Polymorphus minutus have been studied in vitro under conditions designed to approximate to those in vivo. The results of the investigation of the absorption of glucose are compatible with the assumption that a carrier system is involved in the transport of glucose. The carrier system is half-saturated at an external glucose concentration of about 0·25 mg./ml. and is tending towards full saturation when the external glucose concentration reaches 2·0 mg./ml. P. minutus has been shown to be capable of absorbing glucose against a concentration gradient. The rate of glucose absorption, at a given glucose concentration, has been found to fall when the worms have been acclimatized to that concentration. It has been estimated that P. minutus requires about 4 μg. glucose/mg. wet weight of worm/hr. in vivo, assuming that the external glucose concentration is at least 2·0 mg./ml. After 4 hr. incubation with radioactive glucose the radioactive label has been detected in a variety of metabolites extracted from the worms. Evidence is presented indicating that these include : glucose, sugar phosphates, maltotriose, UDPG, glycogen, amino sugars, amino acids and organic acids. Trehalose has not been detected in P. minutus, and a possible evolutionary significance of this result is discussed.

Summary The physiological behaviour of the fructose polymers, which are the sole carbohydrate reserve in Jerusalem artichoke tubers, is briefly described. It is suggested that certain enzymes which have been isolated from this tissue can account for these changes, and a theory of their integrated action is put forward: this involves the trisaccharide IF-fructosylsucrose, widely found in fructosan-containing tissues, as a key intermediate, and the enzyme which produces it from sucrose as a controlling biochemical factor. Sucrose itself, both as a substrate and by its direct effect on the other enzymes, also acts as a major means of control. The hypothesis does not involve sugar phosphates or nucleotide sugars, and seems to be applicable to other plants which contain fructosans.

SUMMARY: A 5′-nucleotidase, widely distributed in teleost fish muscles, was purified about 20-fold from Pacific cod (Gadus macrocephalus) by chromatography of a dialyzed aqueous extract of the muscle on DEAE-cellulose. The enzyme was unstable and lost 85% of its activity in 1 hr at 37°C 53% in 10 min at 42°C and 40% in 1 hr at 30°C. It was stable for 6 days at 0°C, could be dialyzed for up to 3 days at 0°C against 1 mM tris buffer pH 7.5 and quickly frozen and thawed without loss of activity. However, it was inactivated rapidly when held at −30°C. Brief exposure to pH 4.0 or 5.0 effected marked destruction. Attempts at further purification by means of chromatography on hydroxylapatite, adsorption using alumina Cγ and starch gel electrophoresis failed due to instability. The enzyme was strongly inhibited by EDTA, pyrophosphate, KF and ZnCl2 (1-10 mM); less markedly inhibited by GSH, 2-mercaptoethanol, carbonate and CaCl2 (10 to 100 mM). It was strongly activated by Mn++ and weakly activated by Mg++. The optimum pH was 7.6, and the Km was 5 × 10−4M with UMP and 8 −4M with IMP. It hydrolyzed, in order of effectiveness, LJMP, IMP, CMP, d-AMP, GMP, d-IMP, d-GMP, d-UMP and AMP, but not p-nitro phenylphosphate, sugar phosphates or a number of other compounds including 2′,3′-nucleotides.

The effects of sugar phosphates, nucleotides, and other phosphorylated compounds on NAD-linked l-glycerol 3-phosphate dehydrogenase from rabbit liver were studied. Glucose-6-P, fructose-1,6-P2, ribose-5-P, ribulose-1,5-P2, 2,3-propanediol-3-P, and 3-P-glycerate, but not 2-P-glycerate, 2,3-P2-glycerate, or glycerol-2-P, inhibited the oxidation of glycerol-3-P in a noncompetitive manner with respect to either glycerol-3-P or NAD+. The inhibition constants were in the range from 1 to 4 mm. These sugar phosphates in the range from 0.4 to 4 mm did not significantly inhibit the reduction of dihydroxyacetone-P at 0.03 mm dihydroxyacetone-P and 0.01 mm NADH. On the other hand, glyceraldehyde-3-P elicited competitive inhibition (Ki = 0.9 mm) with respect to glycerol-3-P and noncompetitive inhibition (Ki = 1.7 mm) with respect to NAD+. Inorganic phosphate in the range from 1 to 20 mm did not significantly affect the oxidation of glycerol-3-P. However, a significant inhibition on the rate of reduction of dihydroxyacetone-P in a noncompetitive manner with respect to either dihydroxyacetone-P or NADH was observed. Nucleotides and pyrophosphate were found to inhibit both the reverse and forward reactions in a competitive manner with respect to NAD+ or its reduced form and in a noncompetitive manner with respect to glycerol-3-P or dihydroxyacetone-P. From the present kinetic studies, it seems that sugar phosphates, phosphoenolpyruvate, and inorganic phosphate interact with different sites of the enzyme. Nucleotides and pyrophosphate likely interact with the enzyme at the site for NAD+. The physiological significance of the findings in relation to the carbohydrate and lipid metabolism is discussed.

Randomly labeled erythritol-14C has been synthesized and incubated with fluoride-poisoned suspensions of dried cells of Propionibacterium pentosaceum. Therefrom labeled glycerol-3-P, glyceric acid-3-P, erythritol-1-P, ribose-5-P, xylulose-5-P, glucose-6-P, fructose-6-P, mannose-6-P, fructose-1,6-di-P, and sedoheptulose-7-P were isolated. Erythritol-14C-1-P accumulated more rapidly than did the other phosphates. Even under conditions in which its dephosphorylation is inhibited it was metabolized to the same products as was erythritol-14C. Also, in short term experiments the addition of unlabeled l-erythritol-1-P to cell preparations actively metabolizing erythritol-14C reduced the amount of label normally found as glyceric acid-3-P. This supports the view that in P. pentosaceum erythritol metabolism proceeds via a series of phosphorylated intermediates, of which l-erythritol-1-P is the primary member. l-Erythritol-1-P can serve as hydrogen donor for the reduction of 2,6-dichloroindophenol in cell-free extracts. Although the product of the oxidation was not isolated, indirect evidence suggests that it is l-erythrulose-1-P and that this compound is the next intermediate in the erythritol fermentation. Labeling dilution experiments indicated that d-erythrose-4-P is not a direct intermediate in the sequence. The formation of labeled formaldehyde in the reaction mixtures lends support to the view that l-erythrulose-1-P, formed from l-erythritol-1-P, undergoes cleavage between the C3 and C4 positions to yield formaldehyde and dihydroxyacetone-P. This cleavage, combined with reactions known to occur in the propionic acid bacteria, provides a source of the labeled C3, C5, C6, and C7 sugar phosphates accumulating in the cell suspensions and an explanation for the substantial quantities of formic acid produced in the fermentation of erythritol.

Summary Measurements of gaseous exchange between green callus tissue cultures of Kalanchoe crenata and air showed that photosynthesis occurred in the green callus. Feeding experiments with 14CO2 showed that 14C was incorporated by green callus into sugars and sugar phosphates in the light, and some 14C was incorporated into organic acids. Organic acids were the main products of dark fixation of 14CO2 by green callus but no activity was detected in sugars or sugar phosphates. The products of 14CO2 fixation in colourless callus were primarily organic acids both in the light and dark and no activity was detected in sugars or sugar phosphates. Green callus did not show a diurnal fluctuation of acid content. This, coupled with the observations that green callus did not show a net fixation of CO2 in the dark, suggested that the green callus did not exhibit crassulacean acid metabolism. Green callus, however, contained greater quantities of malate, citrate and isocitrate than did colourless callus. Enzyme assays suggested that the presence of PEP carboxylase in green callus and its absence in colourless callus might in part contribute to the higher acid levels of green callus.

The products of short time photosynthesis and of enhanced dark 14 CO 2 fixation (illumination in helium prior to addition of 14 CO 2 in dark) by Chlorella pyrenoidosa and Anacystis nidulans were compared. Glycerate 3-phosphate, phosphoenolpyruvate, alanine, and aspartate accounted for the bulk of the 14 C assimilated during enhanced dark fixation while hexose and pentose phosphates accounted for the largest fraction of isotope assimilated during photosynthesis. During the enhanced dark fixation period, glycerate 3-phosphate is carboxyl labeled and glucose 6-phosphate is predominantly labeled in carbon atom 4 with lesser amounts in the upper half of the C 6 chain and traces in carbon atoms 5 and 6. Tracer spread throughout all the carbon atoms of photosynthetically synthesized glycerate 3-phosphate and glucose 6-phosphate. During the enhanced dark fixation period, there was a slow formation of sugar phosphates which subsequently continued at 5 times the initial rate long after the cessation of 14 CO 2 uptake. To explain the kinetics of changes in the labelling patterns and in the limited formation of the sugar phosphates during enhanced dark CO 2 fixation, the suggestion is made that most of the reductant mediating these effects did not have its origin in the preillumination phase. It is concluded that a complete photosynthetic carbon reduction cycle operates to a limited extent, if at all, in the dark period subsequent to preillumination.

An enzyme has been isolated from wheat germ which catalyzes the reaction: ADP-sugar + inorganic phosphate → ADP + sugar phosphate. Maximal activity was found at pH 8–9. The equilibrium of the reaction seems to be completely displaced towards ADP formation. The enzyme acts on ADP-glucose and deADP-glucose and more slowly, on ADP-xylose and ADP-β-glucose. Evidence is presented indicating that inorganic phosphate is incorporated in the terminal position of the nucleotide. Arsenate can be substituted for inorganic phosphate, AMP being the final product.

セルロースイオン交換体を固定相とする糖ならびに糖リン酸混合物のクロマトグラフ分離法について検討を行なった.その結果,ホウ酸形としたDEAEセルロースの250mm×13mmφのカラムを使用し,20℃において,ホウ酸ナトリウム水溶液,ホウ酸ナトリウム-塩化アンモニウム混合水溶液,塩化アンモニウム水溶液,塩化ナトリウム-塩酸混合水溶液を順次切り替えて使用する段階溶離法を適用すれば,fructose, glucose, glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate, fructose1,6-diphosphate, AMP, ATPが良好に分離できた.糖ならびに糖リン酸がDEAEセルローに捕集された場合にはFreundlichの吸着等温式が適用できることが認められた.

— Two types of photoreactions occur in DNA irradiated in aqueous systems with longwave u.v.-light (Λ > 295 nm), namely, (a) thymine dimerization, and (b) single- and double-strand breakage of the sugar phosphate backbone; these two reactions are unrelated. The presence of acetophenone as a photosensitizer caused an increase in dimerization by a factor of 16, and an increase in single-strand breaks by a factor of 4. The number of thymine dimers per single-strand break is about 100 in the sensitized and 25 in the unsensitized reaction. The alteration of the radius of gyration of DNA molecules is that expected by the degradation observed. At the same time the change in hyperchromicity is very small. Therefore as far as can be detected by these methods of investigation the gross conformation of the DNA double helix is stable against thymine dimerization.

14C-labelled 2-(1,2-dihydroxyethyl)-TPP obtained from 3-14C-hydroxypyruvate and TPP with a preparation of pyruvate oxidase from pig heart muscle, when incubated with ribose-5-phosphate and transketolase, yields 14C-sedoheptulose-7-phosphate. Consequently 2-(1,2-dihydroxyethyl)-TPP has the characteristic property of “active glycolic aldehyde” to transfer glycolic aldehyde to an acceptor aldehyde when catalyzed by transketolase.

Onuphic acid, a sugar phosphate polymer extracted from the tube of Hyalinoecia tubicola, has been identified in the tube and in the body of the polychaete by histochemical methods based on the chemical properties of the macromolecule. Comparison of the results with probe microanalysis for selected elements suggests that onuphic acid is located in regions of high phosphorus density in the lateral-ventral glands, in proximity to sulfur but in the absence of calcium and any large local amounts of magnesium.

Extended Huckel molecular orbital calculations are reported on cyclic AMP and its phosphonate analog. A parallel Lennard-Jones potential and molecular orbital study on the barrier to rotation of the adenine base around the sugar phosphate moiety indicates a rather low barrier for both molecules studied (6.6 kcal/mole and less than 6 kcal/mole for the cyclic phosphate and cyclic phosphonate, respectively) with most favorable syn and anti forms possessing similar energies. According to the calculations this low barrier may be the most distinguishable property when compared to the molecule's precursor ATP and enzymically derived product 5′-AMP.

1. 1. The heptulose phosphate formed from nucleoside and from sugar phosphates (glucose 6-phosphate, mannose 6-phosphate, glucose 1-phosphate, fructose 6-phosphate and ribose 5-phosphate) by normal and thiamine-deficient rat tissues was measured under standard conditions. 2. 2. The thiamine-deficient rat exhibited a loss of activity of the enzymes synthesizing heptulose phosphate, particularly in brain, heart, kidney, spleen, lung and hemolysate. 3. 3. Addition of thiamine hydrochloride and thiamine pyrophosphate in vitro did not change the activity of tissue preparations from thiamine-deficient animals. 4. 4. In the presence of triose phosphate, supernatant preparations of thiamine-deficient hemolysate, kidney, liver and lung underwent as much as a three-fold increase in activity (substrates: glucose 6-phosphate, mannose 6-phosphate). The optimum concentration of triose phosphate was 2.5·10−4.

SUMMARY 1. Cell-free extracts of aerobically grown R. rubrum catalyzed phosphorylation of adenosine diphosphate associated with the oxidation of a variety of substrates in the dark. The P:O ratios varied from below 1 with a variety of citric acid cycle intermediates to a maximum of less than 2 with glucose and related sugar phosphates. 2. The oxidative phosphorylation system consisted of a mix- ture of soluble dehydrogenases and a particulate system. The particles contained reduced diphosphopyridine nucleotide oxi- dase, succinoxidase, and transhydrogenase activities. Soluble components were not required for the phosphorylation carried out by the particles oxidizing DPNH or succinate. 3. The oxidative phosphorylation differed markedly from the anaerobic photophosphorylation catalyzed by extracts of light- grown R. rubrum. The former was not affected by antimycin A, Compound SN5949, and 2-n-nonyl-4-hydroxyquinoline N-oxide, whereas the latter was strongly inhibited. Further- more, Amytal, which inhibited DPNH oxidation and associated phosphorylation, did not appreciably affect photophosphoryla- tion. Finally, phenazine methosulfate, which stimulated photo- phosphorylation, inhibited oxidative phosphorylation. 4. Oxidative phosphorylation was carried out by extracts of light-grown R. rubrum and appeared to be associated with the “chromatophore” system which catalyzed photophosphoryla- tion. The oxidative phosphorylation of anaerobically light- grown and aerobically dark-grown R. rubrum were affected in the same manner by inhibitors. 5. An analysis of extracts indicated that preparations from dark-grown and light-grown R. rubrum contained approximately the same amounts of cytochromes b and ~2; on the other hand, the latter extracts contained more than 10 times as much co- enzyme Q and Rhodospirillum heme protein as the former. Acknowledgments-The author is deeply indebted to Dr. Howard Gest for helpful advice during this investigation and for penetrating criticism during the preparation of this report. He also wishes to acknowledge the assistance of Dr. Bernard Shore in the ultracentrifuge analyses. REFERENCES 1. FRENEEL, A.

A new type of phosphohydrolase that can hydrolyze only phosphate esters of sugars was purified from Neisseria meningitidis. The α-d-aldohexose 1-phosphates and d-ketohexose 1-phosphatase served as the best substrates for the sugar phosphate phosphohydrolase. The d-aldohexose 6-phosphates and d-ketohexose 6-phosphates were hydrolyzed at the same rate as the α-d-hexose 1-phosphates, with the exception of d-galactose-6-P and d-mannose-6-P, which followed at 30% and 28.5%, respectively. If the phosphate group of the d-aldohexose 1-phosphates was esterified in the β configuration at the first carbon atom, they no longer served as substrates. Both phosphate ester bonds of fructose-1,6-di-P were hydrolyzed. When position 6 of α-d-glucose-1-P was in the form of a carboxyl group giving the sugar acid α-d-glucuronic acid-1-P, its rate of hydrolysis was reduced only 25%. However, when position 1 of d-glucose-6-P or d-glyceraldehyde-3-P was in the form of a carboxyl group giving the nonsugars 6-P-gluconate and 3-P-glycerate, no significant hydrolysis was observed. The d-pentose phosphates and triose phosphates were hydrolyzed at a slower rate than the d-hexose 1-phosphates. The phosphate esters of the disaccharides α-gentiobiose-1-P and α-lactose-1-P were hydrolyzed at 66% and 15% of that of α-d-glucose-1-P, respectively. Phosphate esters other than the sugar phosphates were not hydrolyzed significantly by the purified enzyme. When cells were cultured in a complete basal medium, most of the sugar phosphate phosphohydrolase activity was specifically released into the sucrose-Tris-ethylenediaminetetraacetate and "cold water wash" fractions, implying a surface localization. When cells were maintained in a salt medium lacking glucose and lactalbumin hydrolysate, most of the activity remained with the insoluble cytoplasmic membrane fraction. The latter activity could be partially released after storing the cells at 1–3° for 3 or more weeks. A method is described for the purification of the sugar phosphate phosphohydrolase from N. meningitidis. A similar type of enzyme was also purified from Escherichia coli. A purified preparation of the sugar phosphate phosphohydrolase moved as a single peak in sedimentation, and the s20,w was calculated to be 3.29 x 10-13 sec.

Mammalian liver hexose-1-phosphate uridylyltransferase (UDP-glucose:α- d -galactose-1-phosphate uridylyltransferase, EC 2.7.7.12) has been shown to be inhibited by various nucleotides. The nature of the inhibition has been examined with regard to the structural requirements of the inhibitory compounds and the possible regulatory function of intracellular nucleotides on enzyme activity. The most potent inhibitors were UTP and UDP which produced significant inhibition of the enzyme at concentrations normally found in liver tissue, UTP, UDP and UMP were linear competitive inhibitors of UDP-glucose with K i of 0.13, 0.35, and 2.3 mM, respectively, and uncompetitive inhibitors of galactose 1-phosphate UDP-glucoronic acid and UDP-mannose caused similar inhibition. The uridine moiety appeared necessary for competition with substrate UDP-glucose since substitution of cytidine, adenine or guanosine in the nucleotide as in CDP-glucose, ADP-glucose or GDP-glucose produced uncompetitive inhibition of UDP-glucose. Nucleotides containing glucose were competitive inhibitors of galactose 1-phosphate while those containing other sugars or without a sugar moiety caused uncompetitive inhibition of the sugar phosphate site.

Incubation of resting cells of Agrobacterium tumefaciens with glucose-1-phosphate resulted in the accumulation of a new sugar phosphate in the suspending medium. Approximately 80% of the glucose-1-phosphate consumed was converted to the new compound, which was identified as α- d - ribo -hexopyranosyl-3-ulose-1-phosphate (3-ketoglucose-1-phosphate). Both utilization of glucose-1-phosphate and accumulation of 3-ketoglucose-1-phosphate were inhibited by 2,4-dinitrophenol, polymyxin, and d -glucose, which are inhibitors of the glucoside transport system of this bacterium but are not inhibitors of d -glucoside-3-dehydrogenase, which is the 3-ketoglucose-1-phosphate-forming enzyme. Consequently, it was concluded that glucose-1-phosphate penetrates into intracellular space by means of an active transport system. The glucose-1-phosphate is converted to 3-ketoglucose-1-phosphate by d -glucoside-3-dehydrogenase, and the 3-ketoglucose-1-phosphate formed reaches the extracellular space by passing through the surface layer of the bacterium.

The potential energy calculations on the sugar-phosphate unit for different puckerings of the sugar are reported in this paper. The results obtained here essentially confirm our earlier predictions made by using criteria of contact distances (hard-sphere potential) and are also supported by observed conformation in crystal structures. The minimum energy conformations of the sugar phosphate unit, along with the preferred orientations of the base with respect to the sugar given in the previous paper, determine the probable conformations of the monomer unit of a polynucleotide (or nucleic acid) chain.

UDPglucose-4-epimerase (EC 5.1.3.2) is shown to exist in two distinct forms in goat and beef liver. The two forms can be distinguished easily by their interaction with sugar phosphates and with substrate. The minor form comprising about 20% of the total activity, is activated by both Gal - i -P and Gal-6-P and is partially inhibited by Glc - i -P . None of these sugars have any effect on the major form except Gal-6-P, which inhibits its activity partially only in the case of goat liver. The major form, however, undergoes inhibition by substrate at higher concentrations. The two forms behave similarly in their requirement for NAD for activity and in their inhibition by UMP. The induced epimerase in yeast fails to show the existence of these two forms.

Summary A calcareous organic soil was extracted by shaking with Na+-resin suspended in 0·2M acetyl acetone at pH 8·3. Fractionation of the fulvic acid on Sephadex G 25 gave (a) a high molecular-weight component which contained inositol tetraand hexa-phosphates and a sugar phosphate; (b) low molecular-weight components which included the mono-, di-, and triphosphate esters of inositol and two sugar phosphates, but no free inositol phosphates. Inositol phosphates and sugar phosphates accounted for 30·2 per cent and 16·6 per cent of the soil organic P respectively. Our evidence indicates that these phosphate esters exist in an organic complex.

1. 1. Centrifuged cell-free extracts and intact cells of Escherichia coli were incubated in presence of glucose and 32Pi under both aerobic and anaerobic c onditions. 2. 2. Radioactively labelled mannitol 1-phosphate and various sugar phosphates were isolated from the media. 3. 3. The concentration levels and labelling of the various compounds containing esterified phosphate, together with the fact that mannitol 1-phosphate accumulates, indicate that fructose 6-phosphate is being used for the reoxidation of reduced diphosphopyridine nucleotide formed in the triose phosphate dehydrogenase reaction.

Extracts of ox-muscle were investigated with a view to identifying the reducing substances present which are responsible for the rapid browning of these extracts at room temperature. Sugar phosphates were found to play an important part and the reactions of these phosphates with amino-acids in extracts and in model systems were followed. The development of colour and flavour in an extract, in a synthetic extract, and in model systems were investigated and found to be a result of the Maillard reaction.

An enzyme, 5'-nucleotidase, was purified from Escherichia coli. With the use of the osmotic shock technique, a 5000-fold purification was achieved with DEAE-cellulose chromatography, hydroxylapatite chromatography, and repeat DEAE-cellulose chromatography. This enzyme hydrolyzes 5'-AMP, ATP, uridine diphosphate glucose and bis(p-nitrophenyl)phosphate. The ratios of specific activities remain constant for the various substrates throughout the purification, and the heat inactivation curves parallel each other. The purified 5'-nucleotidase of E. coli hydrolyzed all 5'-ribo- and deoxyribonucleotides with optimal activity against 5'-AMP. Substitution by a phosphoryl group as in pXp makes a compound resistant, as does substitution by another nucleotide as in pXpY. The enzyme is inactive against all sugar phosphates but will hydrolyze UDP-glucose. The 5'-AMP activity has a pH optimum of 6.0, the ATP activity 6.8, and UDP-glucose activity 7.4. The 5'-AMP activity is stimulated 100-fold by 5 x 10-3 m Co++ and 200-fold by the further addition of Ca++. The enzyme is inhibited by 0.1 m Zn++ and chelating agents. Only Mn++ is effective in replacing the Co++ stimulation of 5'-AMP or ATP hydrolysis, but Co++ is not needed for the UDP-glucose hydrolysis. The enzyme is minimally affected by its ionic environment, but it is highly labile to denaturation in the absence of bovine serum albumin. Phosphate is not inhibitory. The enzyme has been shown to be pure, as judged by molecular sieve chromatography, polyacrylamide disk gel electrophoresis, and ultracentrifugation. An s20,w value of 4.2 has been obtained. A molecular weight of 52,000 was found. The amino acid composition showed no unusual distribution.

The operation of both malate dehydrogenase and glycerate kinase in certain phases of photosynthesis has been implied from previous studies. Malate has been recognized as a quantitatively minor photosynthetic product in algae and some plants in which the Calvin cycle is operative (Calvin and Bassham, 1962), and as an intermediate in the C4-dicarboxylic acid pathway of photosynthesis (Hatch and Slack, 1966; Hatch, Slack and Johnson, 1967; Johnson and Hatch, 1968). Although NADP appears to be the predominant pyridine nucleotide in chloroplast oxidation-reduction reactions, an NADP-malate dehydrogenase has been found neither in leaves nor indeed from any other source. A glycerate kinase appears not to have been reported previously from plant tissues although it has been proposed to operate in the glycollate pathway, the photosynthetic bypass cycle in which glycollate derived from sugar phosphates is apparently converted to 3-phosphoglycerate (Tolbert, 1963). Glycerate kinase has been detected in liver and yeast (Black and Wright, 1956; Ichihara and Greenberg, 1957). This communication reports the presence of an NADP-specific malate dehydrogenase and a glycerate kinase in leaves of both Calvin cycle plants and plants in which the C4-dicarboxylic acid pathway is operative. Some properties of these enzymes are described and evidence for their location in the chloroplasts of maize leaves is presented.

1. 1. The gross composition of the tube of Hyalinoecia tubicola , the source of onophuc acid, is examined. 2. 2. The tube of Chaetopterus variopedatus contains a phosphorus-rich polysaccharide, but other polychaete tubes and calcified tissues examined have not yielded similar substances. 3. 3. The Chaetopterus polymer is characterized and compared with onuphic acid.