共查询到20条相似文献,搜索用时 46 毫秒
1.
Jean E. Patterson David M. Geller 《Biochemical and biophysical research communications》1977,74(3):1220-1226
Bovine liver microsomes contain an albumin having an apparent isoelectric point approximately 0.3 pH unit in excess of bovine serum albumin. Sequence analysis of the purified protein shows that the first ten residues at the amino terminus are: -Asp-Thr-His-Lys. The data suggest that the hexapeptide (underlined), identical to that found in proalbumin from rat liver, is attached to the amino terminus of bovine serum albumin (the last four residues). By analogy with the rat liver system, this protein therefore is bovine proalbumin, a precursor of bovine serum albumin. 相似文献
2.
Wesley C. Pierson Dominick L. Cinti 《Biochemical and biophysical research communications》1977,78(4):1139-1146
The addition of bovine serum albumin to rat liver microsomes resulted in the formation of the reverse type I spectral change (RI). Both the RI and the type I spectral change were obtained with liver microsomes in the of substrate by altering the temperature; an increase in temperature led to the formation of a type I spectral change while a lowering of the temperature resulted in the formation of a RI. This demonstrates that the RI is indeed the reverse of the type I spectral change rather than a modified type II. Temperature was also found to affect the substrate-induced type I and type II spectral changes; an increase in temperature resulted in a decrease in the aminopyrine-induced type I, but an increase in the aniline-induced type II spectral change. 相似文献
3.
Exposure of guinea pig liver microsomes to phospholipase A2 resulted in the nearly complete loss of 17β-hydroxy-steroid oxidoreductase (17β-HSD) activity, the time course of which correlated with phospholipid hydrolysis and lysolecithin formation. Lysolecithin and unsaturated fatty acids added to microsomes also inactivated 17β-HSD indicating that they may contribute to the inactivation by phospholipase A2.If exposure to lysolecithin and fatty acids was minimized by including serum albumin in the reaction mixture, phospholipids were rapidly hydrolyzed; but in this case the extent of 17β-HSD inactivation was less and the rate of loss was significantly slower. The data suggest that phospholipid hydrolysis results in a destabilization of 17β-HSD resulting in the subsequent activity loss.The inactivation of 17β-HSD by lysolecithin and fatty acids has not been reported previously and is suggestive of a possible control mechanism . 相似文献
4.
Stimulation of hepatic cholesterol biosynthesis by oleic acid 总被引:3,自引:0,他引:3
Livers from normal fed male rats were perfused with an erythrocyte-free, bloodless medium containing serum albumin (3%), and glucose (100 mg %). Oleic acid (663 μmoles) bound to albumin, or albumin alone, was infused at a constant rate. Biosynthesis of cholesterol was evaluated by incorporation of radioactivity from 3H2O. Oleic acid stimulated output of cholesterol (1.60 ± 0.08 SEM vs 1.18 ± 0.04 μmoles/g) but did not change the concentration of cholesterol in the liver or hepatic microsomes. Incorporation of 3H into cholesterol was stimulated by oleate; dpm per μmole cholesterol/dpm per μg atom H was 3.94 ± 0.33, 3.46 ± 0.32, and 4.46 ± 0.37 in the total cholesterol of liver, perfusate, and microsomes, respectively, when oleate was infused. Corresponding values when oleate was not infused were 1.71 ± 0.23, 1.62 ± 0.20, and 2.09 ± 0.26, respectively (P<0.001 in all cases). It is suggested that the stimulation of biosynthesis of cholesterol by oleate results from the obligatory requirement of cholesterol, as a moiety of the very low density lipoprotein, for the secretion of triglyceride by the liver. 相似文献
5.
Shoichi Fujita Takashi Usui Masahiko Suzuki Mari Hirasawa Yumiko Mori Hideo Naganuma Tokuji Suzuki 《Biochemical and biophysical research communications》1982,105(3):1233-1239
Metabolism of propranolol in liver microsomes was markedly induced in rats and mice treated with 3-methylcholanthrene (3-MC) or sudan III, inducers of cytochrome P-448. 7,8 Benzoflavone inhibited propranolol metabolism in microsomes from treated rats. 3-MC did not induce propranolol metabolism in genetically nonresponsive mice. High-performance liquid chromatographical analysis of propranolol metabolites revealed a 6-fold increase in propranolol N-desisopropylase activities in liver microsomes from sudan III- or 3-methylcholanthrene-treated rats. It is concluded that propranolol N-desisopropylation is predominantly catalyzed by cytochrome P-448. 相似文献
6.
V V Lyakhovich I B Tsyrlov O A Gromova N B Rivkind 《Biochemical and biophysical research communications》1978,81(4):1329-1335
The self-assembly of 3,4-benzpyrene hydroxylase system from the 3-methylcholanthrene-induced liver microsomes of mice and ( hybrids has been characterized by much higher efficiency than that one from control microsomes of these mice. This phenomenon was not observed in microsomes of mice. These data suggest that the regulation of aggregation process during the molecular morphogenesis of endoplasmic membranes in mice is of a dominantly inherited character. 相似文献
7.
Structure of the "keratosulfate-like" material in liver from a patient with G M1 -gangliosidosis ( -D-galactosidase deficiency) 总被引:3,自引:0,他引:3
Large amounts of a glycopeptide containing galactose, -acetylglucosamine, -acetylgalactosamine and threonine in the ratio 4:3:1:1, together with smaller amounts of mannose, fucose, sialic acid, sulfate, serine, and other amino acids were isolated from the liver of a patient with GM1-gangliosidosis. Treatment with mild alkali and sodium borohydride indicated an -glycosidic linkage between -acetylgalactosamine and threonine. All the hexosamine residues were resistant to sodium metaperiodate whereas 2 out of 4 D-galactose residues were destroyed. Further studies indicated that one of the galactose residues was 1→3 linked to -acetylgalactosamine (as in GM1) and the other 1→4 linked to -acetylglucosamine as found in skeletal keratosulfate. 相似文献
8.
Monica Galliano Lorenzo Minchiotti Paolo Osadarola Monica Stoppini Piero Giagnoni Scott Watkins Jeanne Madison Frank W. Putnam 《生物化学与生物物理学报:疾病的分子基础》1993,1225(1):27-32
Albumin Ortonovo is a slow moving variant of human serum albumin which has been found only in people coming from the small villages of Ortonovo and Nicola (Liguria, Italy) and reaches polymorphic frequency (≥1%) in the poorly admixed population group living in that area. This is the first report of a ‘private’ varint detected in a Caucasin population. It probably originated as a mutation in a founder individual many generations ago. Isoelectric focusing analysis of CNBr fragments from the purified variant localized the mutation in fragment CNBr (residues 447–548). This fragment was isolated on a preparative scale by reversed-phase HPLC and subjected to V8 proteinase digestion. Sequence analysis of the abnormal V8 peptide revealed that the variant arises from a previously unreported substitution at position 505 where glutamic acid has been replaced by lysine. The protein data were confirmed by DNA sequence analysis which indicated a single nucleotide change of in the corresponding codon of the structural gene. Since the amino acid substitution found in albumin Ortonovo accords with its electrophoretic mobility on cellulose acetate, residue 505 is probably exposed to the solvent. The clustering of the mutations in the intersubdomain connection linking subdomains IIIA and IIIB (residues 492–511) accords with the fact that this region lies on the molecular surface and is accessible to solvent. 相似文献
9.
Addition of -nitroanisole to a reaction mixture containing phenobarbital-pretreated rabbit liver microsomes brings about an increase the reoxidation rate of NADH-reduced cytochrome b5. Addition of partially purified cytochrome b5 to a solution containing microsomes results in a marked increase in both NADH- and NADPH-dependent O-demethylation of -nitroanisole. -Nitroanisole also increases the rate of NADH mediated cytochrome P-450 reduction. From these and other results described in the Discussion section, we confirm that electrons required for NADH-dependent O-demethylation of -nitroanisole is transfered from NADH to cytochrome P-450 via cytochrome b5 and that cytochrome P-450 is the enzyme which catalyzes -nitroanisole O-demethylation. 相似文献
10.
Soluble extracts of and were found to catalyze the specific transfer of arginine from a mixture of [14C] aminoacyl-tRNAs into protein. Arginine transfer was stimulated by bovine serum albumin. Glu-Ala, Asp-Ala and cystinyl--Ala inhibited incorporation into protein, whereas dipeptides with other NH2-terminal residues linked to alanine did not. These results indicate the presence of an enzyme in eucaryotic protists with the same donor and acceptor specificity as mammalian arginyl-tRNA-protein transferase. 相似文献
11.
Bengt Jernström Jorge Capdevila Sten Jakobsson Sten Orrenius 《Biochemical and biophysical research communications》1975,64(3):814-822
Cytochrome P-450 from rat lung microsomes has been solubilized and purified 8-fold by using affinity chromatography on an ω-amino--octyl derivative of Sepharose 4B. The purified fraction was free of cytochrome 5 and NADPH-cytochrome reductase and showed spectral characteristics similar to those of lung microsomal cytochrome P-450. When combined with NADPH-cytochrome reductase partially purified from liver microsomes, the cytochrome P-450 fraction supported the hydroxylation of benzo (α)pyrene and the activity was proportional to the content of the hemoprotein. No absolute requirement for phosphatidylcholine was found. 相似文献
12.
During incubation of 6,7-3H-ethynylestradiol with rat liver microsomes up to 20 % of the radioactivity was bound irreversibly to the microsomal proteins. Incubations in presence of albumin resulted in a further radioactive labelling of the albumin. The irreversible nature of the steroid-protein bond was established by solvent extraction and charcoal treatment. Further evidence was obtained after hydrolyzing the microsomal protein with trypsin and submitting the labelled tryptic peptides to ion exchange chromatography and electrophoresis. The labelled albumin was applied to sephadex gel filtration which showed the association of the ethynylestradiol radioactivity to the albumin peak.The binding reaction required supply of NADPH, could be stimulated by pretreatment of the animals with phenobarbital and was inhibited by CO and SKF 525 A. On these characteristics the concept was based that, in analogy to the well known binding of estradiol and estrone, 2hydroxylation is also an essential prerequisite for the binding of ethynylestradiol. The concept was confirmed by trapping off the 2-hydroxy-ethynylestradiol with glutathione, which led to a decrease of the ethynylestradiol-protein binding.Further evidence resulted from experiments , dosing rats with 6,7-3H-ethynylestradiol and 6,7-3H-estradiol 48 hrs prior to sacrifice and examining the amount of radioactivity irreversibly bound to the liver endoplasmic reticulum. 3H-ethynylestradiol caused a radioactive labelling of microsomes twice as much as that after 3H-estradiol. 相似文献
13.
Joon H. Rho 《Analytical biochemistry》1980,105(1):414-423
We have examined the metabolites produced by in vitro incubation of benzo(a)pyrene with 3-methylcholanthrene-induced mice liver microsomes. Our objective was to observe directly a possible difference in microsomal enzyme systems of animal models having different susceptibility to chemical carcinogens. The metabolites produced by the two animal models, and mice, were analyzed by a highly sensitive, “three-dimensional” fluorescence plotting technique. The fluorescence spectra of the total ethyl acetate-soluble metabolites clearly indicate that the metabolites produced by enzymes were predominantly monohydroxylated benzo(a)pyrene while those produced by the liver microsomes of were highly enriched with the 7,8-dihydrodihydroxybenzo(a)pyrene type. 相似文献
14.
Karl Dus William J. Litchfield Anne G. Miguel Theodore A. van der Hoeven David A. Haugen William L. Dean Minor J. Coon 《Biochemical and biophysical research communications》1974,60(1):15-21
The cytochrome P-450 of (P-450cam) and that of phenobarbital-induced liver microsomes (P-450LM) differ markedly in substrate specificity, solubility, and the requirement of the former for an iron-sulfur protein and the latter for a phospholipid for hydroxylation activity. Despite these differences, highly purified P-450cam and P-450LM show immunological cross reaction by competitive binding and inhibition of catalytic activity and are of similar subunit molecular weight and amino acid composition. Upon treatment with cyanogen bromide they yield small heme-containing peptides of highly similar amino acid composition. 相似文献
15.
E Ambellan 《Biochemical and biophysical research communications》1974,57(2):520-525
Glucocorticoid binding to certain cell particles of rat liver and thymus following treatments and consists in part of a very “tight binding” that resists hot and cold perchloric acid extractions. This binding is found in thymus nuclei and in liver cytoplasmic particles, but not in liver nuclei nor in thymus mitochondria or microsomes. The existence of “tight binding” coincides with the ability of the same particles to bind free corticoid directly in incubations . The difference in the cellular location of this binding suggests that different methods of glucocorticoid activation exist in the anabolic target tissue, liver, and the catabolic target tissue, rat thymus. 相似文献
16.
The amino acid sequences of type I collagen containing α1(I) and α2 chains at a ratio of 2:1, and of type III collagen consisting of α1 (III) chains are known. A statistical analysis of the sequences of these α chains is presented. The inter-chain comparison showed a high level of homology between the three α chains. The interactive amino acids, such as the polar charged and part of the hydrophobic residues responsible for the assembly of the molecules, are strongly conserved. The intra-chain analysis revealed that the α chains are divided into four related D units, each with a length of 234 residues. Between the D units within a chain the polar residues show a higher variability than the hydrophobic amino acids.Besides the D units, other periodicities such as (78 residues), (39 residues), (21 residues) and (18 residues) were observed, particularly in α1 (I) and α1 (III). The D unit is a functional repeat that is formed by the interactive polar charged and hydrophobic residues and which determines the aggregation of the molecules. The unit is mainly pronounced by the non-interactive residues such as proline and alanine and appears to be a reminiscence of a primordial gene. The smaller periodic repeating units may be considered as additional genetic units or as structural units, which determine the triplehelical pitch and thus the lateral aggregation of the molecules.In contrast to α1 (I) and α1 (III), the α2 chain shows less regularity in its internal structure. 相似文献
17.
NADPH-dependent reductase solubilized from microsomes by peroxidation and its activity 总被引:1,自引:0,他引:1
Johan Högberg Robert E. Larson Annika Kristoferson Sten Orrenius 《Biochemical and biophysical research communications》1974,56(3):836-842
Isolated rat liver microsomes were subjected to enzymatic or non-enzymatic lipid peroxidation . NADPH-dependent cytochrome reductase activity was released from the microsomes into the media during peroxidation. This activity could be recovered from the media by DEAE-cellulose chromatography. The recovered enzyme retained high activity for the reduction of cytochrome and a lower level of activity for the reduction of cytochrome P-450. The active fractions were capable of enzymatically supporting the peroxidation of isolated mitochondria in the presence of organically complexed Fe+3 and NADPH, and in this respect the specific activity was found to be about ten times higher than in microsomes. 相似文献
18.
Mark S. Miller Richard C. Bruch Harold B. White 《Biochimica et Biophysica Acta (BBA)/General Subjects》1982,715(1):126-136
Riboflavin-binding proteins (RBP) purified from chicken egg white, yolk and the serum of laying hens differ in their carbohydrate compositions reflecting tissue-specific modifications of a single gene product. All three are complex glycoproteins having more than twice as many N-acetylglucosamine residues (>12) as mannose residues (approx. 6). Egg white RBP is distinctive in having only one sialic acid and two galactose residues. Serum RBP contains approx. five sialic acid and seven galactose residues. In addition there is one residue of fucose. The carbohydrate composition of yolk RBP indicates the hydrolysis, respectively, of one, one, two and 3 residues of sialic acid, fucose, galactose, and N-acetylglucosamine from its precursor, serum RBP. The effect of these differing levels of glycosylation on plasma clearance, ovarian uptake and tissue distribution of 125I-labeled riboflavin-binding proteins in laying hens were compared. 2 h after intravenous injection, 19% of the egg white RBP, 29% of the yolk RBP, and 37% of the serum RBP remained in circulation. The kinetics of plasma clearance was distinctly biphasic for each of the radioiodinated proteins. The initial rapid-turnover component () ranged from 27% of the serum RBP sample to 48% of the egg white RBP sample. The remaining slow-turnover components were cleared with half-lives fo 81 min (egg white RBP), 101 min (yokl RBP), and 121 min (serum RBP). 16 h after injection, only 4% of the egg white RBP was deposited in the yolk of developing oocytes while about 12% of the serum RBP and yolk RBP was deposited. This higly significant difference is apparently due to preferential, carbohydrate-dependent clearance of egg white RBP by the liver rather than preferential uptake of serum and yolk RBP by the ovarian follicle. We find no evidence for carbohydrate-directed uptake of riboflavin-binding protein by the ovarian follicle. 相似文献
19.
P Sepulveda K W Jackson J Tang 《Biochemical and biophysical research communications》1975,63(4):1106-1112
The amino acid sequences near the amino termini of human pepsin (34 residues) and gastricsin (24 residues) and the acid protease from (27 residues) have been determined using automated Edman degradation. From these results three additional observations were made. First, two structural variants have been observed for human gastricsin and for the protease. Both cases are apparently genetic in origin. Second, a stretch of sequence in the protease, residues 14 to 26, is highly homologous to the known sequence of porcine pepsin at the region of residues 11 to 23. Third, the sequences of the NH2-terminal region of human pepsin and gastrisin are homologous. 相似文献
20.
The effect of extra bound cytochrome b-5 on cytochrome P-450-dependent enzyme activities in liver microsomes 总被引:1,自引:0,他引:1
Binding of increasing amounts of detergent-purified cytochrome to rabbit liver microsomes produces a progressive inhibition of NADPH-cytochrome P-450 reductase activity which is accompanied by a similar inhibition of NADPH-supported benzphetamine demethylation. In contrast, NADH-cytochrome P-450 reductase activity in the enriched microsomes is markedly enhanced and this stimulation is accompanied by a similar increase in NADH-peroxidase activity, suggesting that cytochrome in these two reactions functions as an intermediate electron carrier to cytochrome P-450. 相似文献