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Several properties of partially purified phosphoprotein phosphatase from chick embryo are described. The enzyme was active toward casein, phosvitin and phosphopeptone, but not toward low molecular weight phosphate esters including aliphatic and aromatic phos-phomonoesters, a phosphodiester, pyrophosphates and phosphoamides. The enzyme was not activated by reducing compounds. Heavy metal ions and sulfhydryl inhibitors inhibited the enzyme activity, but the inhibited enzyme was partially reactivated with cysteine. Metal chelating agents also inhibited the activity. To the oxalate treated enzyme, Fe++ and Co++ had a stimulatory effect. Differences in property between phosphoprotein phosphatases of chick embryo and of mammalian tissues are discussed.

Both crystalline Japanese-radish peroxidase a and c could catalyze the aerobic destruction of indole-3-acetic acid in the presence of a small amount of hydrogen peroxide as an inducer. The pH dependences of the enzymic activities of peroxidase a and c were different from each other. The optimum pH of peroxidase a was found at 3.6, while that of peroxidase c lied in a broad range over 3 to 4.8. In lower concentrations of both peroxidases at pH 3.8 and 6.0, the major product of the reaction was identical with that presented by Ray with using an Omphalia enzyme, which would probably be methyldioxindole, while, in higher concentrations of both peroxidases at pH 3.8, the major product was found to be indole-aldehyde.

As a part of extensive program on microbial utilization of hydrocarbons, lipid components of Candida petrophillum SD-14 grown on n-alkanes and glucose as carbon sources were studied. In any carbon source, cellular fatty acids of the yeast contained palmitic, palmitoleic, stearic, oleic and linoleic acids as major components.When n-tridecane was fed to the yeast, fatty acids with odd- and even-number of carbon atoms were produced in almost identical quantity. Another yeast, Torulopsis petrophillum SD-77, also gave a very similar fatty acid pattern by n-tridecane substrate. These phenomena indicate the existence of C2 addition and β-oxidation of the fatty acid formed in the yeasts.In the cases of n-tridecane, n-hexadecane and glucose as substrate, about a half of SD-14’s lipid was phospholipid, which consisted of phosphatidyl ethanolamine and phosphatidyl choline principally. Free alcohol and wax were not detected in any case.

The effect of a single intravenous or oral administration of mitomycin C (MMC), 5-fluorouracil (5-FU) or cyclophosphamide (CP) on drug absorption was studied in rats in relation to changes in membrane characteristics. At 48 h after pretreatment, a differential effect on the absorption of sulfanilamide and L-tryptophan was observed in in situ recirculation experiments. Intravenous MMC administration suppressed the absorption of both sulfanilamide and L-tryptophan to a similar extent as a higher oral dose of this agent. Dosing with 5-FU via both routes caused the largest but almost equal suppression of L-tryptophan absorption. However, CP had no effect on the absorption of the two drugs. Differences in these effects were considered to reflect their pharmacological and pharmacokinetic properties. Absorption of drugs from the small intestine had a positive correlation with small intestinal wet weight regardless of the antitumor drug used, pretreatment doses and routes of administration and the results indicated that the change in absorptive surface area played a major role in this phenomenon. Toxicity to intestinal mucosa was shown to derive from an effect on dividing cells in the crypts because MMC and 5-FU preferentially decreased thymidine kinase activity. However, at the membrane level, increased mucosal membrance permeability was also confirmed by measuring the release rates of D-glucose from liposomes consisting of mucosal total lipids obtained from the antitumor drug-treated rats. Pretreatment with lipophilic and polymeric prodrugs of MMC did not exhibit any effect on drug absorption and thus, the possibility of alleviation of toxicity and adverse reactions via the prodrug approach was suggested.

To elucidate the mechanisms underlying the dysfunctions of intestinal absorption induced by antitumor drugs, the effect of pretreatment with mitomycin C on sodium gradient-dependent D-glucose and L-alanine transports was studied in rat brush-border membrane vesicles. 24, 48, 96, or 120 h following a single intravenous injection of mitomycin C, brush-border membrane vesicles were prepared from rat small-intestines. The uptake of D-glucose and L-alanine was shown to be Na+ gradient-dependent even in the case of vesicles obtained from mitomycin C-treated rats, but uptake rates measured at 15 s and magnitude of overshooting effect in uptake of both solutes were decreased in vesicles maximally from 48 h mitomycin C-treated rats. The rate of D-glucose uptake calculated at 15 s recovered to the control level in vesicles prepared at 96 h and 120 h after mitomycin C-treatment, indicating that the effect of mitomycin C on Na+ gradient-dependent D-glucose transport would be fully reversible. Tracer exchange experiments under Na+ and D-glucose equilibrated conditions indicated that the Na+/D-glucose transporters were similarly operative in the vesicles from control and 48 h mitomycin C-treated rats. Rates of 22Na+ uptake measured at 15 s in vesicles from 48 h mitomycin C-treated rats, however, were increased. The increased permeability to Na+ might bring about a more rapid dissipation of the Na+ gradient in these vesicles and this would secondarily cause the decrease in Na+-dependent D-glucose uptake in vesicles from mitomycin C-treated rats.

チキンエキスから得られる抗酸化性ジペプチドのアンセリン(Ans),カルノシン(Car)及びその混合体(AC mix)の抗酸化活性を調べるために,生体内で生成される3種類の活性酸素,次亜塩素酸(ClO⋅),水酸化(OH⋅)及び過酸化亜硝酸(NO3⋅)ラジカルを用いて,これらの活性酸素による蛋白質分解に対する分解阻止作用の点から試験し,ビタミンC(V.C),ビタミンE(V.E),還元型グルタチオン(GSH),エピガロカテキンガレート(EGCG)及びケルセチン(Qur)などの抗酸化剤と比較した.食品の抗酸化能測定法として一般に用いられるラジカル色素還元法(DPPH法)で比較すると,抗酸化活性の強さは植物由来の抗酸化剤,特にポリフェノール化合物が極めて高く測定され,AC mixの抗酸化活性はEGCGの1/6700,Qurの1/2500,そしてV.CとV.Eの1/1000に過ぎなかった.各種活性酸素による蛋白質分解反応の阻止作用で測定した抗酸化活性では,Ans,Car及びAC mixはGSHやV.Cと同様にClO⋅とONOO⋅に対して強い抗酸化活性を示し,OH⋅に対して弱い活性であった.一方,50μMのEGCGとQuer及びV.Eなどの脂溶性抗酸化剤はOH⋅に対し強い抗酸化作用を示したが,ClO⋅とONOO⋅に対しては強い抗酸化活性は示さなかった.V.CはAC mixやGSHと同様にOH⋅に対する抗酸化活性は弱いものであったが,ONOO⋅に対して最も強い抗酸化活性を示した.これらの結果から,抗酸化剤にはそれぞれ有効に作用する活性酸素種があり,生体のエネルギー代謝の過程で発生する活性酸素による生体成分の障害を防止するために適切な抗酸化剤の併用が重要であることが強く示唆された.