Search

The kinetics of the Streptomyces griseus protease-3-catalyzed hydrolysis of p-nitrophenylacetate have been studied by stopped-flow techniques with widely varied initial concentrations of enzyme and substrate. The results obtained are consistent with a three-step mechanism in which there is a rapid equilibration between enzyme and substrate to form a Michaelis complex with a dissociation constant in the order of 10 mM, followed by a moderately rapid formation of an acyl-enzyme and a rate-limiting deacylation of this intermediate. Estimated rate constants for the latter two reaction steps are 15 s-1 and 0.09 s-1, respectively. The presence of a nucleophile such as methanol results in a partitioning of the deacylation process, reflected by a linear dependence of the maximum steady-state reaction velocity on the concentration of methanol. This observation provides confirmatory evidence for a rate-limiting deacylation step in the catalytic mechanism. [ABSTRACT FROM AUTHOR]

1. Steady-state analysis of product inhibition shows that the most probable kinetic mechanism of intestinal sucrase is ping-pong bi-bi (ordered uni-bi for hydrolysis alone). 2. The site of activation by Na+ was tentatively localized at a level prior to the further trans- formation of the ‘glucose’ · enzyme complex. 3. Tris(hydroxymethyl)aminomethane competes with the substrate for the glucose subsite. 4. In the appendix a simple kinetic text is described for detecting or ruling out a mutual competition between inhibitors of different or of identical kinetic type. [ABSTRACT FROM AUTHOR]

An account is given of an investigation of methods For the fractionation of solvent-extracted wool grease into distinct non-polar, semi-polar, and highly polar groups. The non-polar fraction is conventionally referred to as unoxidized grease and the semi-polar fractions are referred to as oxidized grease. The highly polar fraction possesses strong surface-active properties and is not identified forthwith as being strictly a part of the grease constituent of raw wool. The methods were applied lo determine quantitatively the extent of oxidation of a wool grease and the amount of amphiphilic or surface-active matter, including synthetic detergents, extracted by the solvent from a wool sample or an aliquot of an aqueous emulsion, in addition, it is demonstrated that the amount of methanol-insoluble matter in solvent-extracted wool grease is closely related to, and could be used to predict, the maximum efficiency of recovery of grease in a centrifuge. [ABSTRACT FROM AUTHOR]

Copyright of Weed Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hexose phosphate synthetase activity was found in cell-free extracts of methanol-grown Candida boidinii. Incubation of this crude extract with C-formaldehyde and D-ribose-5-phosphate leads to incorporation of radioactivity into fructose-and glucose phosphates. Cells grown on glucose lack the hexose phosphate synthetase activity. No hydroxypyruvate reductase activity, the key enzyme of the serine pathway was found. These results indicate that during growth of C. boidinii on methanol, cell constituents are made by a sugar phosphate pathway similar in concept, if not in absolute molecular detail, to the ribose phosphate cycle in C-metabolizing bacteria. [ABSTRACT FROM AUTHOR]

A methanol extraction residue (MER) of BCG has previously been shown to heighten host resistance to a subsequent challenge with microorganisms or syngeneic tumour grafts and to stimulate the antibody response to sheep red blood cells (SRBC) and phage T2. Present investigations on the effect of antigen dose on MER stimulation of the primary and secondary response to SRBC indicated that: (1) Pretreatment by MER stimulates the early primary response most effectively when the immunizing dose of SRBC is less than maximum, and this is due to a greater increase by MER of 19S antibody with low doses of antigen than with high doses of SRBC. Maximum 7S antibody production is higher in MER treated animals at all antigen doses. (2) MER administered after low doses of SRBC but not high doses stimulates the ongoing primary haemagglutinin response. (3) Maximum secondary responses of mice treated with MER before priming are considerably elevated above the corresponding controls and the secondary responses in treated mice are not inhibited by high priming doses of antigen. These results are discussed in relation to the locus of MER activity. [ABSTRACT FROM AUTHOR]

A study was made of the nature of mouse (host) antigens adsorbed by schistosomula of Schistosoma mansoni. Using the mixed antiglobulin test, extracts of a number of individual mouse tissues were tested for their ability to coat schistosomula. All were effective to some extent, with the greatest activity being found in extracts of the lung and spleen. Antibodies against the schistosomulum-coating antigen as well as surface host antigens of adult Schistosoma mansoni were removed by absorbing with erythrocytes from a number of Forssman-positive but not Forssman-negative animal species. These antibodies were also absorbed by Forssman-positive guineapig kidney extract and methanol soluble (Forssman-positive) but not insoluble fractions of sheep erythrocyte stromata and mouse lungs. Schistosomula could be coated in vitro with methanol soluble fractions of mouse lung and erythrocytes and sheep erythrocytes. Though both mouse and sheep coating antigens reacted with anti-mouse and anti-sheep antibodies, reactions were stronger with the homologous antiserum. It was concluded that schistosomula of Schistosoma mansoni adsorb from mice an antigen similar but not identical to the Forssman antigen of sheep erythrocytes, and that this antigen is also found on the surface of adult worms. [ABSTRACT FROM AUTHOR]

Studies were continued on the mode of action of a methanol-insoluble moiety (methanol-extraction residue) of attenuated tubercle bacilli which enhances the immune response. We analysed the effects of treatment with this material on the primary and secondary immune responses of mice to two antigens, sheep red blood cell and T2 phage. Pretreatment with methanol-extraction residue enhanced the primary response to sheep red blood cells, accelerating the formation of both 19S and 7S plaque-forming cells and of circulating haemagglutinins, and prolonging high levels of 19S and 7S plaque-forming cells. Methanol-extraction residue delayed the secondary response to sheep red blood cells when administered between primary and secondary immunization. Methanol- extraction residue administration subsequent to immunization did not affect an ongoing primary response to this antigen. Administration of methanol-extraction residue before primary immunization with T2 phage, or between primary and secondary immunizations, enhanced both the primary and secondary circulating antibody responses to this antigen. The findings are discussed in relation to possible sites of action of methanol-extraction residue. [ABSTRACT FROM AUTHOR]

The nature, seasonal variation and mobilization of reserves in Malus × domestica have been studied by means of 14C, carbohydrate analyses and extractions of xylem sap. Following exposure to 14CO2 in the autumn, the majority of the 14C absorbed is found in the root. During the winter and in particular the spring the amounts of 14C in the top and root are reduced to approximately 40 per cent of the autumn values; in the root the amount of dry matter was also considerably reduced. In the tops, most of the 14C absorbed was found as methanol (80%)-soluble 14C which also showed the greatest seasonal reduction; sorbitol, sucrose or glucose in particular are responsible for the decrease in concentration within this fraction. Maximum values for methanol-insoluble 14C were found in March. In the root, the highest values for absolute changes were found for methanol- insoluble 14C. Hydrolysis of this fraction showed considerable activity in glucose. In the root there was also considerable activity in a precipitated fraction of the methanol extract. Eluates of xylem sap from apple branches contained primarily sorbitol, the highest concentration of which was found at the beginning of March. For a tree with a dry matter weight of about 300 g, the utilization of reserves from the tree in the spring was calculated to be at least 13 g of dry matter. However, only a minor part (less than 25 per cent) of the latter appears to serve as building material for new growth. [ABSTRACT FROM AUTHOR]

Field grown leaves of sugar beet contained 0.89 % of their fresh weight as chloroform:methanol 1:2 extractable material, whereas climate chamber grown material contained 0.34, 0.15, and 0.16 % in leaves, stalks, and roots respectively. A striking feature was high proportion of sulfolipid: 7 % of the total extractable of the field grown leaves, 19.5, 28.0, and 37.0 % of the total extractable of respectively leaves, stalks, and roots from the climate chamber grown material. Among the fatty acids, all chain lengths from C12 to C28 were found, except only C17 and C19. -- Exceptionally high contents of fatty acids with a chain length of C26 or C28 were noted in some cases. The 2500-20,000 g fraction of root homogenates contained 19 % of the total root lipids. Almost all of the phosphatidyl choline and about half of the phosphatidyl ethanolamine, but only 5 % of the sulfolipid followed the fraction. A fractionation of conjugates lipid types was evident, with a loss of 18/2 and 18/3 conjugates, and with an increase in the proportions of 16/0 and, possibly, of the long-chain (around C260 conjugates. The unspecific ATPase activity of the 2500-20,000 g fraction was rendered specific for (Na+ + K+) stimulation by treatment with 0.1 % deoxycholate for 1 hour. This induced a more than 2-fold swelling of the preparation. About half of its total lipids were lost. Again, this loss was a fractions one, so that the phosphatidyl choline lost its long-chain (about C26) fatty acid conjugate while the short to medium length chain conjugates remained; whereas the reverse was the case with the sulfolipid. The ATPase activity of the 2500-20,000 g fraction was destroyed by a 24 hour treatment with deoxycholate. As compared with the 1 hour treatment, the preparation lost about 20 % both of its volume and of its chloroform:methanol extractable material. The quantitatively dominating loss was found in the (pigment + neutral fat) fraction. The monogalactosyl diglyceride, the phosphatidyl inositol, and a strongly acidic unknown fraction survived the deoxycholate treatments comparatively well. In the sulfolipid the fractionating effect of the prolonged deoxycholate treatment expressed itself as a loss mainly from the long-chain (about C26) fatty acid conjugate. The (Na+ + K+) stimulation of the ATPase function of the particulate preparation is thus correlated with the balance between the long-chain (about C26) fatty acid conjugates of zwitterionic phosphatidyl choline and anionic sulfolipid. This is of theoretical interest, since it indicates that the specific lipid composition under appropriate conditions may influence the charge and conformation of a lipoprotein complex, thereby determining its functional capacities. [ABSTRACT FROM AUTHOR]

The localization of immunoglobulins IgA, IgG and IgM in porcine intestinal tissue by immunofluorescence is described and the influence of three fixatives, ethanol, methanol and acetone on the findings compared. Methanol was found to be the only fixative to give consistent results for IgM; it was also the reagent of choice for the localization of IgA in cells of the lamina propria. However ethanol and acetone were preferred for the demonstration of secretory IgA. Extravascular IgG was shown to be still soluble after fixation and capable of being removed from the tissue. The demonstration of IgM in intestinal crypt epithelium is reported and its possible role as a secretory antibody acting in concert with IgA is discussed. [ABSTRACT FROM AUTHOR]

Provides information on TRIS (hydroxymethyl) amino-methane (THAM) for pediatric application. Physical and chemical properties of THAM; Volume of distribution; Excretion of THAM; Therapeutic uses of THAM.

Natural variants and chemically modified derivatives of phalloidin have been found or prepared which show all degrees of toxicity. High toxicity persists if only three of the side chains are modified. Acetylation of two of the four OH groups of phalloidin leads to less toxic products, the triacetyl derivative is nontoxic. On tosylation toxicity disappeared after reaction of only two OH groups. Alkylation of the indole nitrogen leads to equally or less toxic (N-methyl, -ethyl, carbamoylmethyl, -tert.butyl) or nontoxic (N-propyl, -pentyl) products. Toxicity is also com- pletely absent if only one of the two rings of the molecule is intact. In optical rotatory dispersion spectra all of the toxic compounds show in aqueous solution two cotton effects centered around 300 nm and 248 nm, whereas in nearly all of the nontoxic derivatives at least one of the effects is missing. Triacetylphalloidin and tribromophalloidin, both nontoxic, also exhibit “toxic” curves in water. Their conformation, however, changes on going to organic solvents like methanol or acetonitril as observed by optical rotatory dispersion studies. Thus, stability of the “aqueous” conformation in a lipophilic environment is apparently the second prerequisite for a toxic action of phallopeptides. [ABSTRACT FROM AUTHOR]

Natural variants and chemically modified derivatives of phalloidin have been found or prepared which show all degrees of toxicity. High toxicity persists if only three of the side chains are modified. Acetylation of two of the four OH groups of phalloidin leads to less toxic products, the triacetyl derivative is nontoxic. On tosylation toxicity disappeared after reaction of only two OH groups. Alkylation of the indole nitrogen leads to equally or less toxic (N-methyl, -ethyl, carbamoylmethyl, -tert.butyl) or nontoxic (N-propyl, -pentyl) products. Toxicity is also completely absent if only one of the two rings of the molecule is intact. In optical rotatory dispersion spectra all of the toxic compounds show in aqueous solution two cotton effects centered around 300 nm and 248 nm, whereas in nearly all of the nontoxic derivatives at least one of the effects is missing. Triacetylphalloidin and tribromophalloidin, both nontoxic, also exhibit “toxic” curves in water. Their conformation, however, changes on going to organic solvents like methanol or acetonitril as observed by optical rotatory dispersion studies. Thus, stability of the “aqueous” conformation in a lipophflic environment is apparently the second prerequisite for a toxic action of phallopeptides. [ABSTRACT FROM AUTHOR]

1 Bis(hydroxymethyl)peroxide formerly reported to inhibit horseradish peroxidase, was found not to influence the enzyme. 2. Hydroxymethylhydroperoxide, which may be formed from bis(hydroxymethyl)peroxide by hydrolysis, irreversibly inhibits horseradish peroxidase in a second-order reaction, k = 3.0 x 10²/sec-1 x M-1at pH 4.27 in 6.7 mM guaiacol. 3. Hydroxymethylhydroperoxide is a perioxide substrate of horseradish peroxidase, hydroxymethylhydroperoxide and horseradish peroxidase was indirectly determined to be 2 x 105sec-1 x M -1 at pH 4.27 [ABSTRACT FROM AUTHOR]

1. A careful study of the ionic behavior of α-chymotypsin and chymotrypsinogen has shown that all the α- and ε-amino groups of these proteins are capable of their normal ionization. 2. The ionic difference between chymotrypsinogen and α-chymotrypsin is that expected from the known route of activation and these may be attributed to two C-terminal caboxyl groups (pK' 3.8 ± 0.2) and two N-termial α-amino groups (pK' 7.8 ± 0.2). 3. The two N-terminal amino groups react with formaldehyde to form hydroxymethyl derivatives with pK' ... 5. 4. All the amino groups of the proteins examined react quantitatively with formaldehyde to tbrm hydroxymethyl derivativatives and this reaction appears to be complete in 15-30 sec. 5. α-Chymotrypsin is catalytically active in 3.1 M formaldehyde with: (a) diminution of the catalytic rate, (b) retention of aU active sites, and (c) a bell-shaped kcat/K'm us. pH profile similar to that obtained in water. These data coupled with the present findings appear to be inconsistent with the postulated involvement of the α-amino group of the N-terminal isoleucine residue in the catalytic activity of α-chymotrypsin. [ABSTRACT FROM AUTHOR]

The reduction of diacetyl and acetoin has been shown to be catalyzed by one enzyme in Aerobacter aerogenes. The ratio of the two activities remains constant, during purification into homogeneity, and the two activities appear in the same amount when the growing cells are exposed to acetate. [ABSTRACT FROM AUTHOR]

Earlier studies on inactivation of xanthine oxidase induced by methanol and accompanied by development of a specific electron paramagnetic resonance signal (the Inhibited signal) have been extended. The same reaction takes place when enzyme is treated with formaldehyde. With this, time-courses for signal development and disappearance of enzymic activity cannot be distinguished. Under a variety of conditions, disappearance of the signal accompanied by partial restoration of activity could be achieved. Side reactions also take place in the presence of formaldehyde. Electron paramagnetic resonance parameters of the Inhibited sisal are reported. In the signal-giving species a single non-exchangeable proton interacts with Mo(V) in the enzyme active site. Experiments with C²H3OH and with ²HC²HO show that this proton is derived from the inactivating agent. It is proposed that a formyl residue, -CHO, becomes attached to a group in the active centre and that interaction of molybdenum with this residue stables he five-valent state of the metal, thus preventing enzyme turnover. Methanol is presumed to be oxidized to formaldehyde at the active centre before taking part in the reaction. [ABSTRACT FROM AUTHOR]

The tryptic hydrolysis of L-lysine -methyl ester, L-lysine paranitroanilide and L-tyrosine methyl ester has been studied as a function of pH. In addition, these reactions have been studied in the presence of methanol as a nucleophilic reagent which competes with water in the deacylation step. With lysine methyl ester, a bell-shaped profile for kcat vs pH has been observed. The optimum pH for this substrate occurs at pH 5.8. Km decreases 200-fold when the pH is increased from pH 5 to 8.5. From the nucleophilic competition data, it ear be deduced that the k2/k'3 ratio increases between pit 4.8 and 5.8 with deacylation as rate-determining step. With tyrosine methyl ester, the profiles of both kcat and Km vs pH are ball-shaped, but the pH optimum in this ease occurs at a pH higher than with lysine methyl ester (pH 7.5). The nucleophilic competition data indicate that the acylation step is rate-limiting for this substrate. With lysine paranitroanilide, kcat increases when the put is increased from 5 to 6.5, but at higher pH, the kinetic behavior of this substrate is complicated by a non-Michaelian saturation phenomenon, probably related to transpeptidation. From the quantitative interpretation of our experimental data, the following conclusions could be drawn: 1. The conjugate acids are more reactive than their corresponding α-amino acid derivatives. 2. In the acylenzyme formed with bieationic conjugate acid of lysine methyl ester, the active imidazole pK is strongly displaced from its -normal value to the acidic region. (This pK is lowered from 6.90 in the -free enzyme to 4.80 in this acylenzyme.) These two first points explain the anomalous value of the pH optimum for this substrate. 3. The pK shift is less pronounced in the Michaelis complex formed with the conjugate acid of tyrosine methyl ester, lysine methyl ester and lysine paranitroanilide. Since this pK shift can be interpreted as resulting from a repulsive electrostatic interaction between the imidazolium group of enzyme and the α-ammonium group of the substrate, our data suggest a change of the active site geometry (including substrate) after the acylation step. The comparison of the kinetic parameters obtained in this work with those of corresponding α-N-acyl derivatives suggests that the α-peptidic linkage is an important structural factor for the acylation step but not for the deacylation. Finally, the effect of possible transpeptidation reaction on the kinetic data is discussed. [ABSTRACT FROM AUTHOR]

1. The exchange between 3-hydroxy-3-methylglutaryl-CoA and [14C]CoASH is not catalysed by hydroxymethylglutaryl-CoA reductase. 2. The addition compound of (RS)-mevaldate and CoASH, most probably a diastereomeric mixture of hemithioacetals, is a good substrate for the reductase. Km and Vmax for the new substrate were determined and the possibility of its intermediate nature in the hydroxymethyl-glutaryl-CoA reductase reaction discussed. [ABSTRACT FROM AUTHOR]

Substrate-free incubated erythrocytes and reticulocytes of rabbits form 14CO2 from [3-14C]- serine. The 14C02 formation from [3-14C]serine exhibits a maturation-dependent maximum, which is about ten times higher than that of erythrocytes. The production of 14CO2 from [3-14C]serine requires the splitting off of the hydroxymethyl group with formation of glycine. Serine undergoes neither desamination nor transamination. This is indicated by the fact that neither pyruvate, nor lactate or alanine are labelled. The β-carbon- atom of [3-14C]serine is found in the porphyrines and the 14CO2 formed from serine is diluted by inactive formate. In erythrocytes the 14C02 is formed exclusively from formate by the peroxidative action of catalase. If catalase is irreversibly inhibited with 3-amino-1,2,4-triazole the 14CO2 formation from [3-14C]serine is completely suppressed. In reticulocytes there exists a second catalase-independent pathway of 14CO2 formation from [3-14C]serine, which is proposed to be as follows: condensation of formyl-tetrahydrofolate with succinyl-CoA with formation of α-ketoglutar-semialdehyde, its oxidation to α-ketoglutarate and oxidative decarboxylation to succinate. This pathway is indicated by the dilution of 14CO2 from [3-14C]serine by glycine and particularly by the incorporation of the β-carbon-atom of serine in α-ketoglutarate. [ABSTRACT FROM AUTHOR]

Phycoerythrobilin, one of two tetrapyrrolic prosthetic groups in R-phycoerythrin, was the source of two crystalline urobilinoid pigments. One (catalytic urobilin peb) was prepared from phycoerythrobilin by hydrogenation followed by partial reoxidation of the resulting chromogen, and the other (isomeric urobilin peb) by prototropic isomerisation of phycoerythrobilin while still attached to protein. Both resembled d-urobilin in possessing high dextrorotatory optical activity in chloroform solution and it is concluded that phycoerythrobilin contains one assymetric centre which has the same absolute configuration as the two centres shown previously in d-urobilin. Isomeric urobilin peb must be formed under the influence of a stereospecific­directing influence which leads to its containing two assymetric centres having the same absolute configuration as those in d-urobilin. The optical activity of both urobilins from phycoerythrobilin was greatly reduced by methanol and trifluoroacetic acid, suggesting that in non-polar solvents they are internally hydrogen bonded. [ABSTRACT FROM AUTHOR]

Glucose-less DNA of the T-even bacteriophage type was glucosylated in vitro by the T4-specific hydroxymethylcytosine α- and β-glucosyltransferases separately and by mixtures of the two enzymes in the presence of varying concentrations of Mg++ ions. The α- and β-glucose content of the glucosylated 5-hydroxymethylcytosine residues in the recovered DNA was analyzed. The results indicate that the 5-hydroxymethylcytosine-α-glucosyltransferases is not capable of glucosylating hydroxymethyldeoxycytidine residues linked through their 5' carbon to a neighbouring 5-hydroxymethyldeoxycytidine nucleotide, whereas the β-glucosyltransferases will react with such 5-hydroxymethylcytosine residues. 5-Hydroxymethyldeoxycytidine nucleotides in all the other sequences examined are susceptible to both enzymes. In the presence of both transferases the ratio of α- and β-glucose residues introduced in vitro can be influenced by changing the Mg++ content of the incubation mixture. This situation applies to 5-hydroxymethylcytosine residues generally and to the 5-hydroxymethylcytosine nucleotides present in some specific sequence. The proportion of α- and β-glucosides in T4 DNA produced in vivo has been found to remain constant irrespective of the Mg++ content of the growth medium. [ABSTRACT FROM AUTHOR]

Liver alcohol dehydrogenase is reversibly inactivated by pyridoxal 5′-phosphate. When the enzyme is saturated with pyridoxal-P the residual activity is about 20%. The enzyme can be completely inactivated by successive covalent labelling with pyridoxal-P, using sodium borohydride reduction. A maximum of about 11 pyridoxal-P groups per subunit were covalently incorporated into the enzyme. The binding to the enzyme of several known inhibitors was investigated by studying their effect on the reversible inactivation of the enzyme by pyridoxal-P at pH 8.0. The effect of these uganda on the activation of the enzyme by methyl picolinimidate was also studied. AMP protected competitively against inactivation by pyridoxal-P and also protected strongly against activation by methyl picolinimidate. After picolinimidylation of the enzyme the binding of AMP at pH 10 was 8-fold weaker. AMP and NADU both protected one lysine residue per subunit from reaction with pyridoxal-P. It is concluded that there is one lysine residue at the active centre of the enzyme and that this lysine plays an important part in binding the coenzyme by attracting the phosphate group of the AMP moiety of the coenzyme. Coenzyme binding to the picolinimidylated enzyme is weakened by steric interference between the picolinomidylated active-centre lysine and the AMP moiety of the coenzyme. Since effects of neutral zinc-binding ligands cannot be explained by steric or electrostatic effects, it is suggested that they produce conformational changes in the enzyme, perhaps by binding at a site other than the active-centre zinc atom. [ABSTRACT FROM AUTHOR]

The low-molecular-weight component of rat brain supernatant, which catalyzed the oxygen-dependent cleavage of tile vinyl-ether linkage of plasmalogen, was purified by chromatography on SE-Sephadex and DEAE-Sephadex. A compound was obtained with an absorption peak at 266 nm. It catalyzed the commensurate vinyl-ether cleavage and oxygen reduction. Evidence is presented that this purified active component is identical with, or very similar to ascorbic acid. Commercial ascorbic acid mimicked the vinyl-ether cleaving properties of the active component of rat brain supernatant. Contrary to the rat brain supernatant, the purified active component was unstable and lost activity on heating or storage. Furthermore, vinyl-ether cleavage and oxygen uptake ceased after 2—3 min. Addition of a protein of rat brain, which by itself was inactive, extended the reaction time for 15—20 min. In the course of the reaction, 3.5—4 mol oxygen were consumed and 0.3 tool of ascorbate disappeared for each mole of vinyl-ether-linkage cleaved. Small quantities of compounds which reacted with thiobarbituric acid were also formed in the course of the reaction. The products of the reaction were lysolecithin and several split products produced from the aldehydogenic moiety of the plasmalogen molecule: these reacted with p-nitrophenylhydrazine. Using silicic acid chromatography, about 10—20% of the total carbonyl-containing compounds were eluted with chloroform—methanol (95:5, by vol.), these were identified as pentadecanal in the presence of smaller quantities of heptadecanal. The p-nitrophenylhydrazones of the products were prepared and separated into 3—4 spots on thin-layer silica gel plates. The fastest moving spot was identified by infrared and mass spectrometry as a hydroxy-aldehyde, probably α-hydroxyhexadecanal. A reaction mechanism is proposed as follows: A ferrous-ascorbate complex reduces and forms an “active” oxygen. This attacks the vinyl-ether-linkage of the plasmalogen forming a diol. Hydrolysis of this diol yields α-hydroxy-hexadecanal; oxidative cleavage of this bond yields pentadecanal. [ABSTRACT FROM AUTHOR]

Copyright of Archiv für Toxikologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The formation of crosslinks depends on resonance stabilization of carbonium ion centered on the methylene carbon. The rate of formaldehyde add-on is increased by increasing hydrogen ion activity and by including an alcohol in the formaldehyde-acid solution, thus making hemiformal appear to be the most active formaldehyde source. [ABSTRACT FROM PUBLISHER]

Leaving-group and other effects in acid-catalyzed nucleophilic substitution reactions with a number of 4,5-disubstituted ethyleneureas, 1,3-disubstituted ethyleneureas, and N-substituted methyl carbamates are considered. Acetoxy and secondary alkoxy leaving groups enhance reactivity from formaldehyde-hased (primary carhonium ion formed) systems hut not from glyoxal-based (secondary carhonium ion formed) systems. The 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) molecule, for best reaction with cotton or other nucleophiles should be activated by selected leavint; groups on the methylenes in the 1,3-positions, but not necessarily in the 4,5-positions. Reactivity to small nucleophiles of 1,3- and 4,5-positions in DMDHEU systems are equal when leaving groups are hydroxy or methoxy. Ring (4,5-) positions are hindered. Other factors which influence reactivity or carhonium-immonium ion stability in DMDHEU are discussed. Evidence is presented which suggests that anhydroglucose units in cellulose possess groups of different leaving ability which will influence the location and durability of agents reacted with cellulose. Implications of these findings on the finishing of cotton cellulose are discussed. [ABSTRACT FROM PUBLISHER]

Sodium cellulosates containing from 0.5-1.9 mequivs of Na+ per gram of fabric were prepared by reacting cotton in methanolic solutions of sodium methoxide. The sodium cellulosates were reacted with β-chloroethyldiethylamine in t-butanol to form diethylaminoethyl (DEAE) cottons of greater than 1.0% nitrogen. These DEAE -cottons, easily pre pared at room temperature, were readily converted to the quaternary-base cellulose anion exchangers. Quaternary-base anion exchangers of lower capacity were prepared by reacting sodium cellulosates with glycidyltrimethylammonium chloride. Anion exchangers prepared in nonaqueous media did not differ in fabric properties from anion exchangers of similar capacities prepared in aqueous media. Ability of amino groups to catalyze cellulose-epoxide reactions was not significantly different in DEAE-cottons prepared in nonaqueous and in aqueous media. [ABSTRACT FROM PUBLISHER]

Potassium cellulosates of rayon fibers were formed by means of an exchange reaction between preswollen rayon yarns and potassium methoxide in anhydrous methanol. Degree of substitution (DS) values up to one are achieved by control of the potassium methoxide concentration, and the reaction is complete in about 5 min at room temperature. Significantly higher DS values are obtained at any given potassium methoxide concentration by the use of such cosolvents as dimethyl sulfoxide and pyridine. Analytical studies indicate that at least 80-90% of the bound potassium is in the form of a true cellulosate. The exchange reaction used to form the cellulosate does not lead to chemical degradation of the cellulose, as determined from intrinsic viscosity and mechanical properties measurements. The potassium cellulosates are highly reactive intermediates for the preparation of cellulose derivatives, and act as initiators for the anionic graft polymeriza tion of vinyl monomers. [ABSTRACT FROM PUBLISHER]

Experiments are described in which cross-linking agents containing N-hydroxymethyl, N-methoxymethyl, or aziridinyl groups were tested for their effectiveness in stabilizing set in chlorinated wool by a delayed-cure procedure that involved the application of the cross-linking agent and sodium bisulphite to fabric, followed by setting and curing. Premature cross-linking, leading to unstable set, occurred with all the reagents tested except hexamethoxymethylmelamine. [ABSTRACT FROM AUTHOR]

A simple rapid method developed for the quantitative estimation of the various constituents of fleece wools is reported. The method is primarily based on visual estimations of the fibre qualities and the dirt and vegetable-matter contents of the fleece wools. These visual estimates are then related to significant correlations found to exist for a large number of fleece wools so that the average contents of the various remaining constituents may be rapidly estimated. This method of estimating the contents of the various constituents in fleece wools is especially useful in the scouring of raw wool, Where strict emphasis is being placed on efficiency and economy of operation, since it is possible to determine the optimum conditions of raw-wool feed-rate, detergent consumption, liquor back-flow, etc., to employ in a given wool-scouring machine from such estimates. It was found that the cumulative sum of the naturally occurring grease, suint, and moisture constituents deviates only slightly from a value of about 30% of the fleece weight, independently of the origin of the wool fleece. Since the remaining 70% of the fleece weight is composed of the dry-fibre, dirt, and vegetable-matter constituents, then only variations in the two last-named components will significantly affect the yield of a fleece. The best correlation found to exist was between the methanol-soluble matter in wool grease and the wool-grease content. It demonstrated that the highest contents of oxidized grease will be found in fleeces having the highest grease contents, whereas the actual oxidized fraction of the grease is generally lowest in these wools. [ABSTRACT FROM AUTHOR]

Examines whether the herbicides atrazine and linuron are volatile when dried onto aluminum planchets. Maceration of the shoots of wheat plants with either methanol or acetone; Impact of infrared lamps on the rate at which samples dry during planchet preparation; Losses in radioactivity.

Sterile plants of maize, pea, and cucumber contain less auxin (extracted with methanol or ether) than nonsterile ones. The auxin content is restored within one day by reinfecting sterile plants (or only the shoots, with roots and culture medium remaining sterile) with epiphytic bacteria strains able to produce IAA or with soaking water of nonsterile seeds. Reinfection with bacteria strains unable to produce IAA is ineffective. — The possibility of a bacterial auxin production during methanol extraction was excluded. [ABSTRACT FROM AUTHOR]

The present paper reports an attempt to elucidate the storage and mobilization processes in 1-year-old apple rootstocks by studying the 14C content of different parts of the tree following application of 14CO2. The translocation of the 14C taken up from the leaves to other parts proceeds at the highest rate during the first few days after the application of 14C. The distribution in shoots, trunk and roots after application of 14C during May, July, August, and in part of September depends in particular upon the intensity of growth in the various parts. From the time of the application of 14C until leaf-fall, 40-50 per cent of the 14C initially absorbed disappears from the tree. After exposure to 14C during October, and in part of September, a relatively large part of the 14C applied goes to the root. In this case there is a considerable reduction in the 14C-content from leaf-fall to the following spring after leafing, especially in the root, although relatively speaking reduction is also considerable in the bark of the parts above ground, and it is most pronounced in the methanol (80 %) soluble fraction. The reduction takes place primarily during spring, and comprises, after application during October, for the whole tree 20-25 per cent of the 14C initially absorbed. Only 13-17 per cent of this amount was recovered in the newly developed shoots and leaves in the following June. [ABSTRACT FROM AUTHOR]

A study of the cuttings of Salix atrocinerea Brot. was made by extraction with methanol, paper chromatography and Avena coleoptile straight growth test. In the acidic fraction, indole-3-acetic acid (IAA; about 15 μg per kg fresh weight) and p-hydroxybenzoic acid (PHB; about 850 μg per kg fresh weight) were isolated and identified. The growth activity of the different zones is explained by their content of these two compounds. The watersoluble residue, insoluble in ether, showed growth stimulating activity, which probably is due to a bound auxin (IAA-sugar); alkaline breakdown of this aqueous residue, giving PHB, vanillic and p-coumaric acids, suggests the presence (in the cuttings of Salix atrocinerea) of glycosides with aglycones similar to rhamnacine and scutellareine. [ABSTRACT FROM AUTHOR]

Woody cuttings of Ribes rubrum, an easy plant to root, were extracted with methanol. One fraction of this extract was both water and ether soluble; a part of it was only water soluble. From the water and ether soluble fraction a crystalline compound was isolated which was fully identified with p-hydroxybenzoic acid (PHB) by m.p., mixed m.p., infrared spectrum, ultraviolet absorption in neutral and alkaline methanol and chemical analyses. For Avena coleoptiles straight growth test, p-hydroxybenzoic acid was found to have a significant growth promoting activity in the range 20-100 μg/ml, and it showed strong growth inhibition at concentrations higher than 200 μg/ml. From the same extract fraction a phenolic ester was isolated by paper chromatography which showed a weak growth inhibiting activity. This compound was identified as an ester of p-hydroxybenzoic acid by micro-scale reactions. From the extract soluble only in water further amounts of crystalline p-hydroxybenzoic acid were obtained by alkaline hydrolysis. This PHB may have arisen from the breakdown of pelargonidin glucosides. [ABSTRACT FROM AUTHOR]

Isolated wheat roots in light and in the presence of iron, show a marked inhibition of the cell elongation. Six low molecular weight, primary alcohols (ethyl, n-propyl, n-butyl, isobutyl, n-amyl, isoamyl) are able to reverse the light inhibition and to restore the cell length as compared with the dark controls, if added in moderate concentrations (10-2 M to 10-3 M). They exert no growth promotion in the dark. Methyl alcohol and three secondary and tertiary alcohols examined (isopropyl, sec-butyl, tert-amyl) have very little or no effect, either in light or in darkness. Cell multiplication is not influenced, except in concentrations near the toxic ones. These alcohols, except methyl alcohol, became toxic in concentrations of 10-1 M to 10-3 M, the material being more sensitive to the higher molecular weight compounds. [ABSTRACT FROM AUTHOR]

A spectrophotometric method for the identification of tryptophol, indole-3- acetic acid (IAA), and indole-3-acetonitrile (IAN) is described. The method can probably also be applied to other indole derivatives. If the components of a mixture of indolic compounds are to be identified, these must first be separated by chromatographic methods. Procedure. Eluate containing approximately 100 μg. of the indole compound is dissolved in 2.75 ml. of methanol. Ehrlich's reagent (l.5 ml.) is O added. The mixture is heated at 95°C for 2 min., after which 0.25 ml. 1 % NaNO2 in water are added. The mixture is cooled for 30 min. at room temperature. The volume is adjusted to 4.5 ml. with methanol, and the optical density at wavelengths between 470 and 700 mμ is read on a spectrophotometer. Absorption spectra for the reaction products of tryptophol, IAA, and IAN are presented. The method can be used for quantitative determinations of tryptophol in the range 10 to 100 μg. and for IAA between 100 and 500 μg. Supporting evidence for the occurrence of tryptophol in the culture medium from Acetobacter xylinum was provided by using this method. [ABSTRACT FROM AUTHOR]

1. The fluorescent pigment produced by Aspergillus repens was isolated by adsorption on Fuller's earth, elution with methanol, and chromatography upon a magnesia column. Its absorption spectrum shows maxima at 270 and at 370—390 mμ. 2. The fluorescence spectrum of this pigment has a maximum at 455 mμ. 3. These findings, together with data derived from infrared studies and paper chromatography indicate that the fluorescent pigment is a pteridine. 4. Culture filtrates of A. repens also contain a non-fluorescent pigment, auroglaucin. [ABSTRACT FROM AUTHOR]

This study is concerned with the absorption spectra of the anthocyanin pigment of red cabbage, Brassica oleracea L. var. capitata L. f. rubra L. in the visible region. The pigment was obtained in a state of relative purity by a procedure consisting of extraction in boiling water, precipitation of the anthocyanidin as the lead salt, and decomposition of the lead salt with acid. Absorption spectra of aqueous solutions were determined at pH values ranging from 1.0 to 10.0. With change in pH, the pigment varies in color from red to purple to blue to green to yellow. At pH 1.0 and 2.0. there is an absorption peak at 530 mμ. As the pH is increased, the maximal absorption becomes shifted to longer and longer wave lengths, maximum absorption at pH 9.0 being at 615 mμ. At still higher pH values, this peak becomes obliterated, and maximal absorption in the visible then occurs below 420 mμ. These spectral properties indicate that the red cabbage anthocyanin has great potential usefulness as a naturally occurring pH indicator which covers a very wide range. [ABSTRACT FROM AUTHOR]