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1.
2.
Subunit structure of human and rat glutathione S-transferases 总被引:4,自引:0,他引:4
Y C Awasthi S V Singh 《Comparative biochemistry and physiology. B, Comparative biochemistry》1985,82(1):17-23
In rat tissues different forms of glutathione (GSH) S-transferases represent various dimeric combinations of at least four different classes of subunits categorized on the basis of their Mr values as seen on polyacrylamide gels. These subunit types represent heterogeneous populations and the actual number of subunits in rat GSH S-transferases may be far more than is known at present. Human GSH S-transferases arise from dimeric combinations of at least four immunologically and functionally distinct subunits which can be classified into three types, A (Mr 26,500), B (Mr 24,500) and C (Mr 22,500). There is evidence for considerable charge heterogeneity in each of these subunit types. 相似文献
3.
S S Singhal M Saxena H Ahmad S Awasthi A K Haque Y C Awasthi 《Archives of biochemistry and biophysics》1992,299(2):232-241
Glutathione S-transferase (GST) isozymes of human lung have been purified, characterized, quantitated, and, based on their structural and immunological profiles, identified with their respective classes. The tau-, mu-, and alpha-class GSTs represented 94, 3, and 3% activities of total human lung GSTs toward CDNB, respectively, and 60, 10, and 30% of total GST protein, respectively. Both the mu- and the alpha-class GSTs of human lung exhibited heterogeneity. The two mu-class GSTs of human lung had pI values of 6.5 and 6.25 and were differentially expressed in humans. Significant differences were seen between the kinetic properties of these two isozymes and also between the lung and liver mu-class GSTs. The alpha-class GST isozymes of lung resolved into three peaks during isoelectric focusing corresponding to pI values of 9.2, 8.95, and 8.8. All three alpha-class GSTs isozymes had blocked N-termini and were immunologically similar to human liver alpha-class GSTs. Peptide fingerprints generated by SV-8 protease digestion and CNBr cleavage indicated minor structural differences between the liver and the lung alpha-class GSTs. The three alpha-class GSTs of lung expressed glutathione peroxidase activities toward the hydroperoxides of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol, with Km values in the range of 22 to 87 microM and Vmax values in the range of 67-120 mol/mol/min, indicating the involvement of the alpha-class GSTs in the protection mechanisms against peroxidation. All three classes of lung GSTs expressed activities toward leukotriene A4 methyl ester and epoxy stearic acid but the mu-class GSTs had relatively higher activities toward these substrates. 相似文献
4.
The molecular evolution of mammalian Y-linked DNA sequences is of special
interest because of their unique mode of inheritance: most Y- linked
sequences are clonally inherited from father to son. Here we investigate
the use of Y-linked sequences for phylogenetic inference. We describe a
comparative analysis of a 515-bp region from the male sex- determining
locus, Sry, in 22 murine rodents (subfamily Murinae, family Muridae),
including representatives from nine species of Mus, and from two additional
murine genera--Mastomys and Hylomyscus. Percent sequence divergence was
< 0.01% for comparisons between populations within a species and was
0.19%-8.16% for comparisons between species. Our phylogenetic analysis of
12 murine taxa resulted in a single most- parsimonius tree that is highly
concordant with phylogenies based on mitochondrial DNA and allozymes. A
total evidence tree based on the combined data from Sry, mitochondrial DNA,
and allozymes supports (1) the monophyly of the subgenus Mus, (2) its
division into a Palearctic group (M. musculus, M. domesticus, M.
spicilegus, M. Macedonicus, and M. spretus) and an Oriental group (M.
cookii++, M. cervicolor, and M. caroli), and (3) sister-group relationships
between M. spicilegus and M. macedonicus and between M. cookii and M.
cervicolor. We argue that Y- chromosome DNA sequences represent a valuable
new source of characters for phylogenetic inference.
相似文献
5.
S. P. Gautam A. K. Gupta R. Shrivastava M. Awasthi 《World journal of microbiology & biotechnology》1996,12(1):99-100
Two thermostable enzymes produced by the thermophilic fungus Paecilomyces varioti, a chitinase and laminarinase, were used to isolate protoplasts of a thermophilic fungus, Malbranchea sulfurea. The frequency of protoplast regeneration observed (35%) was considerably higher than that obtained using commercial lytic enzymes. 相似文献
6.
Thirty-one Brassica juncea accessions were screened at the cotyledon stage for resistance to four isolates of Peronospora parasitica. Isolates R1 and P003 were derived from crops of oilseed rape (B. napus ssp. oleifera) in the UK and isolates IP01 and IP02 were derived from crops of mustard (B. juncea) in India. B. napus cv. Ariana, which was used as a susceptible control for isolates from B. napus, was resistant to isolates from B. juncea. All, B. juncea accessions were resistant to isolates from B. napus except one accession which expressed moderate resistance to isolate P003. Five groups of B. juncea accessions with differential resistance were identified. Lines homogeneous for resistance were selected from seedling populations of accessions that exhibited a heterogeneous reaction to isolates from B. juncea. The differential resistance identified in the B. juncea-P. parasitica combination can be used as a foundation for future studies of the genetics of the host-pathogen interaction and for breeding for disease resistance. 相似文献
7.
Summary The increased downward mobility of phorate, quinalphos and carbofuran residues was detected in soil with increase in depth
of soil column whereas aldicarb was found to remain localised mainly in 0–7.5 cm and 7.5–15.0 cm layers. Persistence of organophosphate
insecticides was higher as compared to carbamates in all the soil layers. Residues of all the four insecticides got distributed
in all parts of okra plant through uptake but accumulated in higher amounts in fruits only.
Contribution No. 312/83 from I.I.H.R. Bangalore (India) 相似文献
8.
9.
Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells
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Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump. 相似文献
10.
Sita Awasthi Poonam Kakkar P. N. Viswanathan R. Bhardwaj 《Journal of neurochemistry》1991,57(1):277-281
Administration of phenobarbitone caused a marked increase in the capacity of rat brain microsomes to produce thiobarbituric acid-reactive substances in vitro. Enzymatic peroxidation of lipids was more affected than the nonenzymatic processes occurring in heat-inactivated preparations. Analysis of the phospholipid profile showed a drastic decrease in phosphatidylcholine and total phospholipid contents in the exposed animals, but about a fivefold increase in the lysophosphatidylcholine fraction. Data for in vivo incorporation of [14C]choline showed a similar pattern of high radioactivity in lysolecithin. The increase in lipid peroxidation could be related to the higher level of lysolecithin and the accompanying structural and functional changes in microsomes resulting from the neurotoxic effects of phenobarbitone. 相似文献