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Analysis of free sulfhydryl groups and disulfide bonds in Na + ,K + ‐ATPase
Author(s) -
Gevondyan N.M.,
Gevondyan V.S.,
Gavrilyeva E.E.,
Modyanov N.N.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81103-2
Subject(s) - chemistry , titration , disulfide bond , cysteine , crystallography , denaturation (fissile materials) , enzyme , urea , reagent , protein subunit , silver nitrate , stereochemistry , protein disulfide isomerase , biochemistry , inorganic chemistry , nuclear chemistry , organic chemistry , gene
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 accessible thus revealing 22 free SH groups/mol of the protein. After complete blocking of free SH groups with silver ions, 8 SH groups/mol of the protein are being released upon sulfitolysis which indicates the presence of four disulfide bonds in the enzyme. At least one disulfide bridge is located in the α‐subunit whereas the β‐subunit contains three disulfide bonds.