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51.
52.
Metabolic activation by several forms of purified cytochrome P-450 of aflatoxin B1 to a product(s) mutagenic to Salmonella typhimurium TA100 was examined. Of the 5 forms of cytochrome P-450 purified from liver microsomes of untreated and PCB-treated male rats, a constitutive form purified from untreated male rats, P-450-male, and a high-spin form of cytochrome P-450, P-448-H, from PCB-treated rats were highly active. 相似文献
53.
The effects of treatment with phenobarbital, 3-methylcholanthrene or polychlorinated biphenyls (PCB) on the amounts of sex-specific forms of cytochrome P-450, namely P-450-male and P-450-female, in male and female rats were studied. Although treatment with phenobarbital, 3-methylcholanthrene or PCB markedly increased the total amount of hepatic cytochrome P-450, P-450-male and P-450-female were rather decreased or not significantly changed. Thus, the percentages of P-450-male and P-450-female in the total cytochrome P-450 were decreased in liver microsomes from the treated rats. The increases in specific cytochrome P-450, such as P-448-H, P-448-L, and P-450I-c accounted for the increase in the total amount of cytochrome P-450 in the treated rats. The treatment with phenobarbital or PCB increased the activities of testosterone 16 alpha-hydroxylase, benzo(a)pyrene hydroxylase and aminopyrine N-demethylase more markedly in female rats than in male rats. Similarly, the treatment with 3-methylcholanthrene increased benzo(a)pyrene hydroxylase more markedly in female rats. Therefore, the sex-differences in testosterone 16 alpha-hydroxylase, benzo(a)pyrene hydroxylase, and aminopyrine N-demethylase activities became smaller after the drug treatment. These results indicate that sex-specific P-450-male and P-450-female were unaffected, or even depressed by the agents in some cases. 相似文献
54.
Isolation and characterization of the complete complementary and genomic DNA sequences of human serum amyloid P component 总被引:6,自引:0,他引:6
Complementary and genomic DNA clones corresponding to the human serum amyloid P component (SAP) mRNA have been isolated and analyzed. The nucleotide sequences of the cDNA and the corresponding regions of the genomic SAP DNA reported here were identical, and revealed that after coding for a signal peptide of 19 amino acids and the first two amino acids of the mature SAP protein, there is one small intron of 115-base pairs (bp), followed by a nucleotide sequence coding for the remaining 202 amino acid residues. The SAP gene has an ATATAAA sequence 29-bp upstream from the cap site, but there is no CAAT box-like sequence. A possible polyadenylation signal sequence, ATTAAA, was found to be located 28-bp upstream from the polyadenylation site. A comparison of the genomic SAP DNA sequence with that of human C-reactive protein (CRP) revealed a striking overall homology which was not uniform: several highly conserved regions were bounded by non-homologous regions. This comparison provides further support for the hypothesis that SAP and CRP are products of a gene duplication event. 相似文献
55.
H Sakurai H Uchikubo T Yoshimura M Maeda K Kawasaki 《Biochemical and biophysical research communications》1985,130(3):1254-1260
Thiol-containing penta (Leu-Ala-Cys-Ser-Leu) and nona (Leu-Ala-Cys-Ser-Leu-Ile-Glu-Ser-Leu) peptides corresponding to residues 132-136 and 132-140, respectively, of apo-P450 from Psuedomonas putida were synthesized to examine heme-binding by the enzymes in the oxidized (ferric) form. The peptide-hemin complexes prepared in solution were characterized by their optical and ESR spectra. In these complexes without nitrogenous ligands, no ferric complexes in the low-spin state were observed, suggesting that simultaneous axial coordination of Cys-134 (thiolate) and Ser-139 (hydroxyl) of apo-P450cam to the heme is unlikely to occur. In the presence of nitrogenous ligands, such as py, Im and MeIm, the resulting complexes were good models of apo-P450cam-nitrogenous ligand adducts in the low-spin ferric state retaining a thiolate-Fe(III)-nitrogen axial coordination mode, as judged by their spectral pattern as well as by crystal field analysis of ESR g-values. 相似文献
56.
A temperature-sensitive Chinese hamster ovary cell mutant pleiotropically defective in protein export 总被引:8,自引:0,他引:8
We have developed a new selection procedure for mammalian cell mutants defective in protein export by the use of diphtheria toxin, and devised a new screening method for defective protein secretion using nitrocellulose membranes. By the combination of these procedures, we have isolated a temperature-sensitive mutant clone of Chinese hamster ovary cells which shows a pleiotropic defect in protein export. This mutant, designated DS28-6, is temperature-sensitive for growth. Secretion of a series of proteins is markedly inhibited at the non-permissive temperature. These proteins seem to be normally synthesized and accumulated within the cell at the non-permissive temperature and secreted upon shift down to the permissive temperature. When this mutant is infected with vesicular stomatitis virus, oligosaccharide processing of G-protein is arrested at an endoglycosidase-H-sensitive stage at the non-permissive temperature. The lesion of this mutant appears to be in the endoplasmic reticulum or the cis Golgi or both. 相似文献
57.
The formation of the anulospiral ending of Ia fibers in muscle spindles was investigated in the masseter muscle of developing mice. Before 15 days after birth, the complete anulospiral ending was not observed in almost all of the muscle spindles examined. With the growth of mice, the Ia fiber began to construct the spiral ending, and by the 40th postnatal day after weaning, almost all of the Ia fibers of the muscle spindles had complete coiled endings, though the formation still continued in some spindles. The continuous formation of anulospiral endings for a long period after weaning indicates that muscle spindle morphogenesis may be affected by muscle tension in the masseter muscle due to the movement activated after weaning. 相似文献
58.
Macromolecules purified from Lentinus edodes mycelia cultureenhanced adventitious root formation in Azukia epicotyl cuttings.Partial purification by sequential column chromatographies gavematerial composed of 71% polysaccharides and 29% proteins. Thesugar moiety consisted of mainly xylose, glucose and arabinose,the sum of their contents being more than 76% of the total carbohydrates.The protein moiety consisted of mainly glycine and serine, whichaccounted for more than 40% of the total amino acid residues. (Received June 9, 1984; Accepted November 12, 1984) 相似文献
59.
Phorbol ester increases the level of interleukin 2 mRNA in mitogen-stimulated human lymphocytes 总被引:8,自引:0,他引:8
T Hirano K Fujimoto T Teranishi N Nishino K Onoue S Maeda K Shimada 《Journal of immunology (Baltimore, Md. : 1950)》1984,132(5):2165-2167
TPA alone did not induce the production of IL 2 in human tonsillar lymphocytes but enhanced the PHA-induced IL 2 production by seven-fold. That the effect of TPA was due to an increase in IL 2 mRNA was demonstrated by examining the amount of IL 2 mRNA translatable in Xenopus laevis oocytes, and by Northern blotting analysis using IL 2 cDNA as a probe. In these ways, it was shown that TPA alone did not induce any significant IL 2 mRNA synthesis, but when added together with PHA it increased the level of IL 2 mRNA by at least 10-fold, as compared with that induced by PHA alone. 相似文献
60.
Tomoko Ohta 《Journal of molecular evolution》1984,20(3-4):274-280
Summary The previous simple model for treating concerted evolution of multigene families has been revised to be compatible with various new observations on the immunoglobulin variable region family and other families. In the previous model, gene conversion and unequal crossing-over were considered, and it was assumed that genes are randomly arranged on the chromosome; neither subdivision nor correlation of gene identity and chromosomal distance were considered. Although this model satisfactorily explains the observed amino acid diversity within and between species, it fails to predict the very ancient branching of the mouse immunoglobulin heavy chain V-gene family. By incorporating subdivided structure and genetic correlation with chromosomal distance into the simple model, the data of divergence may be satisfactorily explained, as well as the rate of nucleotide substitution and the amino acid diversity. The rate at which a V-gene is duplicated or deleted by conversion or by unequal crossing-over is estimated by the new model to be on the order of 10–6 per year. The model may be applicable to other multigene families, such as those coding for silkmoth chorion or mammalian kallikrein.Contribution no. 1560 from the National Institute of Genetics, Mishima, 411 Japan 相似文献