N. M. Gevondyan

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Exposed regions of the alpha- and beta-subunits of membrane-bound Na+,K+-ATPase were in turn hydrolyzed with trypsin. Resistance of the beta-subunit to proteolysis was shown to be due mainly to the presence of disulfide bridge(s) in the molecule. A model for the spatial organisation of the enzyme in the membrane was proposed on the basis of detailed(More)
The thermal unfolding and domain structure of Na+/K+-ATPase from pig kidney were studied by high-sensitivity differential scanning calorimetry (HS-DSC). The excess heat capacity function of Na+/K+-ATPase displays the unfolding of three cooperative domains with midpoint transition temperatures (Td) of 320.6, 327.5, 331.5 K, respectively. The domain with Td =(More)
Modifications with different thiol reagents demonstrated that 28 of 32 cysteine residues of human IgG1 are involved in the formation of disulfide bonds, and four cysteines remain free. So IgG1 is a protein possessing both free SH-groups and disulfide bonds. Only one of the four SH-groups is accessible for silver or mercury ions and hydrophobic reagents,(More)
To study the topology of Na+,K+-ATPase monoclonal antibodies (MAbs) specific for membrane-bound enzyme were produced. Using immunofluorescence staining of viable cells or smears of a pig kidney embryonic (PKE) cell line, two groups of MAbs were selected, namely those binding to extra- or intracellular portions of the alpha-subunit. The extracellular(More)
The content of free SH groups and disulfide bonds in the purified pig kidney Na+,K+-ATPase was determined by ammetric titration with silver nitrate. In the native enzyme, most of the free SH groups are masked due to their location in the polypeptide chain regions poorly accessible to SH reagents. Denaturation with 5% SDS and 8 M urea makes these regions(More)
For localizing S-S bonds in the pig kidney Na+,K(+)-ATPase alpha subunit, cystine-containing peptides (V-1, VII-1, and VII-2), obtained in our previous study from the enzyme's tryptic digest, were analysed. Chemical modification of the cystine-containing peptides performed at cysteine residues involved successive alkylation, first with radioactive(More)
Tryptic digest of the pig kidney Na+, K(+)-ATPase was subjected to HPLC for separating water-soluble fragments. Using ammetric titration with silver nitrate, disulfide-containing peptides were identified and demonstrated to contain s-s bonds with differential sensitivity to reduction. The amino acid sequences of cystine-containing peptides were determined(More)