Hydrogen evolution by co-immobilized Chlorella vulgaris and Clostridium butyricum cells

Whole cells of Chlorella vulgaris and Clostridium butyricum were co-immobilized in 2% agar gel. NADP was suitable as an electron carrier. The rate of hydrogen evolution increased with increasing NADP concentration. The optimum conditions for hydrogen evolution were pH 7.0 and 37°C. The immobilized C. vulgaris-NADP-immobilized Cl. butyricum system continuously evolved hydrogen at a rate of 0.29–1.34 μmol/h per mg Chl for 6 days. On the other hand, the system without NADP evolved only a trace amount of hydrogen.     

Effects of fat content in the diet on hepatic peroxisomes of the rat

Effects of fat content in the diet on rat liver peroxisomes was examined. In the livers of rats fed for one week on the high-fat diet containing 30% fat, the cyanide-insensitive palmitoyl-CoA oxidation was accelerated to eight times that of control and the enzymic activities of catalase, carnitine acetyltransferase and carnitine palmitoyltransferase were elevated by the factors of 1.3, 5 and 2, respectively. In contrast, the activities of D-amino acid oxidase in addition to the three enzymes mentioned above were all lowered by 20% when the animals were maintained on a fat-free diet for the same period of time. It appears that the high-fat diet-induced increase in the activity of carnitine palmitoyltransferase is a result of the raised activity of this enzyme in mitochondria only while the apparent high activity reflects stimulation of carnitine acetyltransferase in all the subcellular fractions. Another notable effect of the high-fat diet was a remarkable increase in the quantity of a peroxisome-associated polypeptide which was separable by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It is noteworthy that this effect of the high-fat diet resemble that of clofibrate. If the diet was deprived of fat, however, this polypeptide species, with an estimated molecular weight of 80 000, decreased to a level slightly lower than normal. On the basis of the electron micrographic criteria, the high-fat diet provoked a marked proliferation of hepatic peroxisomes.     

Anaerobic biodegradability of polyvinyl alcohol

Summary Biodegradability of polyvinyl alcohol (PVA) under anaerobic conditions was demonstrated using anaerobic river sediments and anaerobically treated activated sludge from a sewage treatment plant. PVA having molecular weights of 2000 and 14000 was over 60% biodegraded as determined by TOC.     

Quantitative structure-activity relationships of structurally similar odorless and odoriferous benzenoid musks

To reveal the difference of molecular property between structurallysimilar odorless and odoriferous musk compounds, 10 pairs ofbenzenoids (monocyclic-, dicyclic- and tricyclic-) were examined.Molecular structures of all compounds were optimized by MNDO(modified neglect of diatomic differential overlap) consideringconformation. Parameters effective in discriminating two groups,group A of 10 odorless compounds and group B of 10 musk odorcompounds, were searched from 34 candidate parameters by adaptiveleast squares. The best three parameters found were log P value(octanol/water partition coefficient), the longest side lengthof hexahedron circumscribing a molecule, and the parameter whichexpresses structural hindrance to the functional group whena molecule approaches the receptor site. The two groups of compoundswere completely discriminated using these three parameters.     

Purification and Characterization of a Substrate-Size-Recognizing Metalloendopeptidase from Streptococcus cremoris H61

During the ripening of Gouda-type cheese, two kinds of endopeptidases were found to participate in the degradation of αs1-CN(f1-23), a specific product from αs1-casein hydrolyzed by chymosin. One of the endopeptidases, lactic acid bacteria endopeptidase (LEP-II), which can recognize the size of its substrates, has already been purified and characterized (T. R. Yan, N. Azuma, S. Kaminogawa, and K. Yamauchi, Eur. J. Biochem. 163:259-265, 1987). The other endopeptidase, LEP-I, was purified to homogeneity by conventional chromatographic techniques from Streptococcus cremoris H61. The enzyme appeared to be monomeric, with an apparent molecular weight of 98,000, and its isoelectric point was 5.1. For the hydrolysis of αs1-CN(f1-23), the enzyme had an optimum pH and temperature of 7.0 to 7.5 and 40°C, respectively. Its activity was inhibited by such chelating agents as EDTA and 1,10-phenanthrolin, and it could be fully reactivated by Mn²⁺. Inhibitors specific for serine and thiol proteases had no effect on the protease activity. The enzyme showed a high affinity toward the Glu-Asn peptide bond of αs1-CN(f1-23) and αs1-CN(f91-100) but showed no hydrolysis activity toward αs1-CN(f1-52), αs1-CN(61-122), αs1-CN(136-196), αs1-casein, β-casein, κ-casein, α-lactalbumin, and β-lactoglobulin. The K_m and V_max of LEP-I for αs1-CN(f1-23) were 14.2 pM and 139 U, respectively.     

Interaction between cytochrome c and cytochrome c peroxidase: excited-state reactions of zinc- and tin-substituted derivatives

The effect of cytochrome c peroxidase (CCP) and apoCCP on the fluorescence and phosphorescence of Zn and Sn cytochrome c (cyt c) and the effect of cyt c on the fluorescence and phosphorescence of Zn CCP were examined. We found the following: The fluorescence yields of Zn and Sn cyt c were quenched by about 20% by CCP, consistent with energy transfer between the two chromophores with a separation of about 1.8 nm. The phosphorescence spectrum of Zn cyt c (but not Sn cyt c) shifts by 20 nm to the blue upon complexation with either CCP or apoCCP; at the same time the phosphorescence lifetime of Zn cyt c decreases from 12 +/- 2 to 6 ms with apoCCP addition. Zn CCP phosphorescence decay increases from 8.3 to 9.1 ms upon addition of poly(L-lysine) used to mimic cyt c. It is concluded from these results that binding of the redox partner or an analogue to Zn CCP and Zn cyt c results in a conformational change. The respective phosphorescence lifetimes of Zn and Sn cyt c were 13 and 3 ms in the absence of CCP and 1.6 and 1.1 ms in the presence of CCP; this corresponds to a quenching rate due to CCP of 519 and 570 s-1, for Zn and Sn cyt c, respectively. The phosphorescence of Zn CCP is also affected by native cyt c but is dramatically less than the complementary pair; the quenching rate constant is 17 s-1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Participation of peroxisomes in lipid biosynthesis in the harderian gland of guinea pig.

Peroxisomal enzyme activities in the guinea-pig harderian gland, which has a unique lipid composition, were studied. Activities of catalase, acyl-CoA oxidase and the cyanide-insensitive acyl-CoA beta-oxidation system in this tissue were comparable with those in rat liver. The activities of dihydroxyacetone phosphate acyltransferase (DHAPAT, EC 2.3.1.42) and alkyl-DHAP synthase (EC 2.5.1.26) were appreciable, and the distributions of both activities were consistent with that of sedimentable catalase activity. Glycerol-3-phosphate acyltransferase (GPAT, EC 2.3.1.15), which is localized in both microsomes (microsomal fractions) and mitochondria in the rat liver, was a peroxisomal enzyme in the harderian gland, though the activity was only about one-tenth of the DHAPAT activity. These enzymes had different pH profiles and substrate specificity. The existence of high activities of enzymes of the acyl-DHAP pathway in peroxisomes suggests the physiological significance of peroxisomes in the biosynthesis of glycerol ether phospholipid and 1-alkyl-2,3-diacylglycerol in the guinea-pig harderian gland.