Accession Number : AD0680610

Title :   PROPERTIES OF SODIUM AND POTASSIUM ACTIVATED ADENOSINE TRIPHOSPHATASES OF RAT BRAIN: EFFECT OF CYCLOPROPANE AND OTHER AGENTS MODIFYING ENZYME ACTIVITY,

Corporate Author : NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CALIF

Personal Author(s) : Trevor,A. J. ; Cummins,Joseph T.

Report Date : 12 NOV 1968

Pagination or Media Count : 25

Abstract : Two ATP-hydrolyzing enzyme systems (ATPases), possibly lipoprotein in nature, have been isolated from particulate fractions of rat cerebral cortex homogenates. They consist of at least two components, one Mg(2+) dependent and the other Mg(2+), Na(+) and K(+) dependent. ATP hydrolysis is measured both by orthophosphate and hydrogen ion liberation. A lack of stoichiometry exists (H(+) ion release 2X orthophosphate formation) over the first 90 seconds of the reaction. H(+) ion and phosphate release are sensitive to strophanthin, but only in the presence of Na(+) and K(+). Sulfyhdryl inhibitors including p-hydroxymercuribenzoate (POMB) and iodoacetate (IAA) inhibit both basic and Na(+)-K(+) activated ATP hydrolysis, but the enzyme system is more resistant to N-ethylamaleimide (NEM), especially the initial 'spurt' of H(+) ion release. Certain gases have an action on enzyme activity, both to decrease (cyclopropane) or increase it (air, nitrogen) at pressures above 1 atmosphere. The significance of the lack of stoichiometry between H(+) ion and orthophosphate release and the action of inhibitory agents is discussed. (Author)

Descriptors :   (*PHOSPHORIC MONOESTER HYDROLASES, CENTRIFUGE SEPARATION), (*ENZYMES, *CEREBRAL CORTEX), (*ENZYME INHIBITORS, *CYCLOPROPANES), HYDROLYSIS, MAGNESIUM COMPOUNDS, POTASSIUM COMPOUNDS, SALTS, ANESTHETICS, METABOLISM, LIPOPROTEINS, ADENOSINE PHOSPHATES

Subject Categories : Biochemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE