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991.
Brahm S. Srivastava 《Molecular & general genetics : MGG》1976,143(3):327-332
Summary The isolation and properties of a new radiation sensitive mutant of Escherichia coli K-12 are described which shows a correlation between radiation sensitivity and replication of irradiated DNA. The mutation, called rer, is located between argB and purD loci. The mutant, when grown in tryptone broth after irradiation, is sensitive to UV and -rays and incorporates little or no 3H-thymidine but in minimal glucose-salts medium both the radiation sensitivity and incorporation of 3H-thymidine remain identical to that of the parent strain. Studies with a temperature sensitive double mutant rer dnaC show that 1 hr incubation of irradiated cells at 42° C before their transfer to 30° C results in higher survival as compared to their incubation at 30° C only. It is suggested that rer controls the replication of irradiated DNA and thus regulates the coordination between replication and repair of DNA. 相似文献
992.
J Fernandes U C Hegde S Srivastava R S Phadke G Govil 《Physiological chemistry and physics and medical NMR》1992,24(1):63-69
The ability of spermatozoa to reduce nitroxide spin--TEMPO has been used as a parameter to understand maturation, capacitation and calcium uptake of sperm obtained from Holstman strain rats. The rate of spin label reduction by sperm follows the trend--caput greater than cauda greater than corpus. With the increase in age, the electron donating capability shows first a gradual increase, for 60- to 85-day-old rats, peaking at 85 days (corresponding to puberty) and leveling off after 92 days. Calcium uptake takes place in two phases which corresponds to accumulation of and activation by calcium. The presence of polyclonal antibody which is known to cause agglutination, does not adversely affect the sperm activity. 相似文献
993.
994.
The 3'-, 4'-, and 6'-deoxy analogs of UDP-GlcpNAc have been synthesized chemically and found to act as donor-substrates for N-acetylglucosaminyltransferase-I (GnT-I) from human milk. Incubation of UDP-GlcpNAc and these deoxy analogs with GnT-I in the presence of alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-beta-D-Manp -O(CH2)8COOMe gave beta-D-GlcpNAc-(1----2)-alpha-D-Manp-(1----3)-[alpha-D-Manp- (1----6)]- beta-D-Manp-O(CH2)8COOMe (6), and the deoxy analogs 12-14 where HO-3, HO-4, and HO-6, respectively, of the beta-D-GlcNAc residue were replaced by hydrogen. The tetrasaccharide glycosides 6 and 12-14 were characterized by 1H-n.m.r. spectroscopy and evaluated as acceptors for GnT-II, the next enzyme in the pathway of biosynthesis of Asn-linked oligosaccharides. Deoxygenation of the 3-position of the beta-D-GlcNAc residue of 6 completely abolished its acceptor activity, whereas removal of HO-4 or HO-6 caused only modest decreases in activity. 相似文献
995.
Phenolic compounds at low concentrations decrease pea diamine oxidase activity without affecting growth, but they have no effect on barley polyamine oxidase in spite of a decrease in growth. 相似文献
996.
An attempt has been made to determine the correlation between liver damage and the virulence of mildly pathogenicMycobacterium avium in thioacetamide treated rabbits. Liver damage increased the susceptibility of rabbits to infection even with a moderately
virulent organism. 相似文献
997.
R. C. Srivastava Bandana Bose R. D. Tripathi D. Mukerji S. N. Mathur 《Biologia Plantarum》1982,24(3):183-187
Chloramphenicol has been found to inhibit nitrate reductase activity in black-gram leaves. It inhibitsin vivo nitrate reductase activity up to 50–67%, and the catalytic property of the enzyme up to a maximum of 70–98%. Modulators,
such as KNO3, NADH and HCO3 could not protect enzyme inhibition by chloramphenicol. It is suggested that the chloramphenicol inhibition is mainly through
its effect on the catalytic process of the enzyme. 相似文献
998.
Isolation of rabbit testicular cathepsin D and its role in the activation of proacrosin 总被引:1,自引:0,他引:1
Cathepsin D was purified 900-fold with 30% recovery from rabbit testes using pepstatin bound Sepharose affinity chromatography. The enzyme is homogeneous as observed by acrylamide gel electrophoresis. The heat stable enzyme exhibits an apparent molecular weight of 42,000 with identical subunits of 20,000. Purified cathepsin D catalyses the conversion of proacrosin to acrosin. 相似文献
999.
Formation of sorbitol 6-phosphate by bovine and human lens aldose reductase, sorbitol dehydrogenase and sorbitol kinase 总被引:2,自引:0,他引:2
Formation of sorbitol 6-phosphate by bovine and human lens aldose reductase and sorbitol dehydrogenase by the reduction of glucose 6-phosphate and fructose 6-phosphate, respectively, has been demonstrated. The reaction product has been identified by Dowex-formate column chromatography, gas chromatography and mass spectrometry. Sorbitol 6-phosphate can also be formed by the phosphorylation of sorbitol by lens sorbitol kinase in the presence of ATP. 相似文献
1000.