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Activation of the purified erythrocyte plasma membrane Ca 2+ ‐ATPase by organic solvents
Author(s) -
Benaim Gustavo,
de Meis Leopoldo
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)80589-7
Subject(s) - chemistry , dimethyl sulfoxide , calmodulin , cooperativity , ethylene glycol , membrane , atpase , glycerol , enzyme , polyethylene glycol , calcium , cooperative binding , chromatography , biochemistry , organic chemistry
In this report it is shown that organic solvents mimic the stimulatory effects of calmodulin and acidic phospholipids on the erythrocyte plasma membrane Ca 2+ ‐ATPase. The solvents used were dimethyl sulfoxide (20%, v/v), glycerol (20%, v/v), ethylene glycol (20%, v/v) and polyethylene glycol ( M r , 6000–8000) (10%, w/v). These solvents increased both the affinity for Ca 2+ and the turnover number of the enzyme. The increase in Ca 2+ affinity is additive to that achieved with calmodulin. The calcium cooperativity observed in the presence of calmodulin disappears after the addition of dimethyl sulfoxide to the medium. The present data support the proposal that activation of the erythrocyte plasma membrane Ca 2+ ‐ATPase is promoted by hydrophobic interactions along the enzyme molecule.