ESSENTIAL ARGINYL RESIDUES IN THE H+ TRANSLOCATING ATPASE OF THE PLASMA MEMBRANE FROM THE YEAST SCHIZOSACCHAROMYCES POMBE
The H**+-translocating adenosine-5'-triphosphatase (ATPase) is inactivated upon incubation with the arginine modifier 2,3-butanedione, maximal at pH values above 8.5 but reactivated when incubated after removal of 2,3- butanedione. The extent of inactivation is half maximal at 10 mM 2,3-butanedione for an incubation of 30 min at 30 degrees C at pH 7.0 and its time dependence is biphasic in a semi-logarithmic plot with half-lifes of 10.9 min and 65.9 min. Incubation with 2,3-butanedione lowering markedly the maximal rate of ATPase activity does not modify the K-m for MgATP. These data suggest that two classes of arginyl residues play essential roles in the plasma membrane ATPase activity. Magnesium adenosine 5'-triphosphate (MgATP) and magnesium adenosine 5'-diphosphate (MgADP) protect partially against enzyme inactivation by 2,3-butanedione. These and other protections indicate either the existence of at least one reactive arginyl in the substrate binding site or a general change of enzyme conformation induced by MgATP, MgADP or free magnesium.
Bibliographic Reference: EUROPEAN JOURNAL OF BIOCHEMISTRY, VOL. 148 (1985), PP. 35-39
Record Number: 1989124018200 / Last updated on: 1987-01-01
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