The International journal of biochemistry最新文献

1. Lipid peroxidation and membrane-related enzyme changes in the cerebral cortex of stroke-prone rats (SHRSP) and normotensive rats were examined at 5 and 20 weeks of age. 2. In vivo formation of thiobarbituric acid-reactant substances was higher in SHRSP at 20 weeks of age and in vitro generation of free malondialdehyde was greater in SHRSP brains, both at 5 and 20 weeks of age, as compared with those in WKY. 3. Membrane-associated enzymes such as Na/K-ATPase and 5'-nucleotidase activities were lower in 20-week-old SHRSP than in age-matched WKY. 4. These results indicate how very prone the SHRSP brain is toward lipid peroxidation and subsequent membrane-related enzyme changes.

1. To characterize an enzyme which metabolizes retinal in liver microsomes, several properties of the enzymatic reaction from retinal to retinoic acid were investigated using rabbit liver microsomes. 2. The maximum pH of the reaction in the liver microsomes was 7.6. 3. The Km and Vmax values for all-trans, 9-cis and 13-cis-retinals were determined. 4. The reaction proceeded in the presence of NADPH and molecular oxygen. 5. The incorporation of one atom of molecular oxygen into retinal was confirmed by using oxygen-18, showing that the reaction comprised monooxygenation, not dehydrogenation. 6. The monooxygenase activity was inhibited by carbon monoxide, phenylisocyanide and anti-NADPH-cytochrome P-450 reductase IgG, but not by anti-cytochrome b5 IgG. 7. The enzymatic activity inhibited by carbon monoxide was photoreversibly restored by light of a wavelength of around 450 nm. 8. The retinal-induced spectra of liver microsomes with three isomeric retinals were type I spectra. 9. The microsomal monooxygenase activity induced by phenobarbital or ethanol were more effective than that by 3-methylcholanthrene, clotrimazole or beta-naphthoflavone. 10. These results showed that the monooxygenase reaction from retinal to retinoic acid in liver microsomes is catalyzed by a cytochrome P-450-linked monooxygenase system.

1. Fibrinogenase was isolated from Candida albicans NH-1 by DEAE-Cellulose, Sephadex G-75 and Sephadex G-100 column chromatographies. 2. The purified fibrinogenase gave a single band on disc polyacrylamide gel electrophoresis, isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis. 3. The enzyme preparation had a molecular weight of 13,000, isoelectric point of pH 4.2 and possessed 117 amino acid residues. 4. The purified fibrinogenase possessed capillary permeability-increasing activity. 5. The enzyme hydrolyzed fibrinogen, casein, hide powder azure, azocoll hydrolytic activities and also hydrolyzed the oxidized B chain of insulin. The cleavage sites in the oxidized B chain of insulin were identified as Asp(3)-Glu(4), Glu(13)-Ala(14), Ala(14)-Leu(15), Tyr(16)-Leu(17), Arg(22)-Gly(23), Phe(25)-Tyr(26) and Tyr(26)-Thr(27). 6. Fibrinogenase activity of this preparation was inhibited by alpha 2-macroglobulin antithrombin-III, o-phenanthroline, disodium ethylenediaminetetra acetic acid and dithiothreitol.

1. In this study, expression of a 60-kDa heat shock protein in rat pancreas was investigated before and after water-immersion stress, which has been known as an exacerbation factor of caerulein-induced pancreatitis in rats, by Western blot. 2. A 60-kDa heat shock protein increased after water-immersion stress in both soluble and insoluble fractions of the pancreas. 3. Serum amylase level and pancreas weight did not increase after water-immersion. 4. No pathologic alteration was observed in the pancreas after water-immersion.

1. The contents of connectin in rabbit cardiac and skeletal muscle were estimated by densitometry of the bands in SDS gel electrophoresis. 2. The weight ratio of connectin to myosin was 1:9.5 in cardiac muscle and 1:4.2 in skeletal muscle. 3. Assuming that the molecular weights of myosin and skeletal muscle connectin were 5.25 x 10(5) and 4.2 x 10(6) respectively, and a myosin filament consists of 300 myosin molecules, it was calculated that there were approx. 4 connectin molecules per half of myosin filament in rabbit skeletal muscle. 4. In cardiac muscle, the molecular weight of connectin was assumed to be 3.6 x 10(6) and it was estimated that there were about 2 connectin filaments per half of myosin filament.

1. Highly purified DNA from calf thymus was phosphorylated with protein kinase NII. 2. Digestion with proteinase K of this DNA demonstrates proteins as phosphorylated component. 3. Gel filtration chromatography on Bio-Gel A-0.5m gel column shows a major protein peak between 50 and 70 kDa. 4. SDS gel electrophoresis, after hydrolysis, to digest completely DNA, shows three major phosphorylated bands corresponding to polypeptides of M(r) between 31 and 21 kDa. 5. After high voltage electrophoresis on TLC plates tryptic digested polypeptides show very similar phosphopeptides patterns.

1. The effect of different concentrations of insulin (INS) and glucagon (GLU) on the rotational mobility of a membrane-incorporated spin probe 2,2-6,6-tetramethyl-4-capriloyl piperidine-1-oxil (C7) was investigated by electron spin resonance (ESR) technique. 2. Two strong adenylate cyclase effectors guanosine 5'-triphosphate (GTP) and guanylyl 5'-imidodiphosphate [Gpp(NH)p], as well as an antioxidant 4-methyl-2,6-ditretbutilphenol (AO) and a nonprotein hormone prostaglandin E2 (PGE2) were used as reference effectors. 3. Applied effectors reduced by 30-82% the rotation correlation time (TR) of the rat liver plasma membranes spin probe C7. The effect was time-dependent and reached saturation 30-40 min after the effector application. 4. The kinetic- and concentration-dependent changes in TR were described by a simple phenomenological model. The apparent binding constants and the number of the apparent membrane binding sites of the effectors used were calculated using the model.

Ferrous iron uptake was investigated in Bifidobacterium thermophilum (B. thermophilum) in the presence of Mg2+ and Ca2+ with the following findings: 1. Mg2+ inhibited Fe2+ accumulation in the cells in a dose-dependent manner at 37 degrees, but not at 0 degrees. Removal of Mg2+ from the medium resulted in a resumption of rapid iron uptake. 2. Mg2+ had no effect on the binding of Fe2+ by B. thermophilum protoplasts, its cellular particulate fraction, or distribution between the particulate and soluble fractions. 3. Ca2+ exerted a stimulatory effect on iron uptake by B. thermophilum, but was not able to reverse the inhibitory effects of Mg2+. 4. It was concluded that Mg2+ has no effect on the binding of iron on the surface or interior of B. thermophilum and that it affected the Fe2+ transport mechanism (permease) in a reversible manner. It is possible that iron and magnesium share the same permease in this microorganism.