Analysis of free sulfhydryl groups and disulfide bonds in Na+,K+-ATPase.
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 alpha-subunit whereas the beta-subunit contains three disulfide bonds.
Gevondyan
N M
NM
Shemyakin Institute of Bioorganic Chemistry, USSR Academy of Sciences, Moscow.
Gevondyan
V S
VS
Gavrilyeva
E E
EE
Modyanov
N N
NN
D000818:Animals; D004220:Disulfides / Q000032:analysis; D007679:Kidney Medulla / Q000201:enzymology; D012835:Silver Nitrate / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000302:isolation & purification / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000032:analysis; D013552:Swine
D004220:Disulfides; D013438:Sulfhydryl Compounds; D012835:Silver Nitrate; D000254:Sodium-Potassium-Exchanging ATPase