Volume 271, Number 43,
Issue of October 25, 1996
pp. 27146-27151
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
Endopolyphosphatases for Long Chain Inorganic Polyphosphate in
Yeast and Mammals
(Received for publication, February 1, 1996, and in revised form, July 8, 1996)
Krishnanand D.
Kumble
and
Arthur
Kornberg
From the Department of Biochemistry, Beckman Center, Stanford
University School of Medicine, Stanford, California 94305-5307
Whereas exopolyphosphatases have been
purified from yeast and a variety of bacteria, this is the first report
characterizing endopolyphosphatases that act on long chain
inorganic polyphosphate (polyP). The activity from Saccharomyces
cerevisiae, localized in vacuoles, has been purified to
homogeneity from a strain that possesses vacuolar proteases. The
endopolyphosphatase is a dimer of 35-kDa subunits. Distributive action
on polyP750 produces shorter chains to a limit of about
polyP60, as well as the more abundant release of
polyP3; the Km for polyP750
is 185 nM. Endopolyphosphatases have been identified in a
wide variety of sources, except for most eubacteria tested. The
activity has been partially purified from rat and bovine brain where
its abundance is about 10 times higher than in other tissues but less
than (null)/1;10 that of yeast; the limit product of digestion of the
partially purified brain enzyme is polyP3.
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