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THE ADENOSINE DIPHOSPHATE‐ADENOSINE TRIPHOSPHATE EXCHANGE REACTION OF EXTRACTED CEREBRAL MICROSOMES
Author(s) -
SWANSON P. D.
Publication year - 1968
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1968.tb06833.x
Subject(s) - microsome , chemistry , adenylate kinase , stimulation , adenosine diphosphate , atpase , adenosine triphosphate , enzyme , sucrose , potassium , biochemistry , adenosine , ion exchange , chromatography , ion , medicine , endocrinology , biology , organic chemistry , platelet , platelet aggregation
—Microsomal fractions prepared from guinea pig cerebral cortex manifested ADP‐ATP exchange activity, 40–99 per cent of which was extractable by dilute salt solutions. All of the (Na + , K + )‐ATPase activity remained in the particulate material. The unextracted ADP‐ATP exchange activity was stimulated six to seven fold by a non‐ionic detergent (Lubrol W). When pre‐extracted microsomes were sedimented in a sucrose density gradient, the ADP‐ATP exchange activity was more widely distributed than (Na + , K + )‐ATPase or adenylate kinase activities. The ADP‐ATP exchange activity of microsomes extracted with NaI was stimulated by Na + ions when the Mg 2+ concentration in the reaction mixture was low (0·2 m m ). The Na + stimulation of exchange activity was more variable than was the stimulation of phosphate formation by Na + plus K + . The Na + ‐stimulated ADP‐ATP exchange reaction of extracted microsomes may be a component of the (Na + , K + )‐ATPase system, which has not been freed from adenylate kinase or possibly other contributing enzyme systems.