{"title":"The mechanism of the modifying effect of ATP on Na(+)-K+ ATPase.","authors":"A A Boldyrev, N U Fedosova, O D Lopina","doi":"","DOIUrl":null,"url":null,"abstract":"<p><p>On the basis of a review of the literature and a study of the molecular and kinetic properties of Na(+)-K+ ATPase, a model is proposed that explains the regulation of the activity of the enzyme by ATP in terms of an acceleration of the E2----E1 transition. It is presumed that the transition occurs via a short-lived oligomer whose formation is accelerated by ATP. In the context of this model, the non-Michaelis-Menton kinetics of the enzyme can be explained by interprotomer interactions. After solubilization of the enzyme with octaethylene glycol dodecyl ether, the hydrolysis of ATP follows ordinary Michaelis-Menton kinetics. The validity of the model is also supported by radiation-inactivation experiments with a nucleotide (GTP) which does not accelerate the E2----E1 transition, as well as by experiments with a low concentration of ATP. In both situations, the size of the molecular target corresponds to the monomeric form of the enzyme.</p>","PeriodicalId":77499,"journal":{"name":"Biomedical science","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1991-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Biomedical science","FirstCategoryId":"1085","ListUrlMain":"","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
On the basis of a review of the literature and a study of the molecular and kinetic properties of Na(+)-K+ ATPase, a model is proposed that explains the regulation of the activity of the enzyme by ATP in terms of an acceleration of the E2----E1 transition. It is presumed that the transition occurs via a short-lived oligomer whose formation is accelerated by ATP. In the context of this model, the non-Michaelis-Menton kinetics of the enzyme can be explained by interprotomer interactions. After solubilization of the enzyme with octaethylene glycol dodecyl ether, the hydrolysis of ATP follows ordinary Michaelis-Menton kinetics. The validity of the model is also supported by radiation-inactivation experiments with a nucleotide (GTP) which does not accelerate the E2----E1 transition, as well as by experiments with a low concentration of ATP. In both situations, the size of the molecular target corresponds to the monomeric form of the enzyme.