132
F. M. HUENNEKENS AND H. R. WHITELEY
in fact, highly polymerized polyphosphate (110). The formation of
"volutin" by yeast and bacteria requires an oxidizable substrate, phosphate, and potassium ions (133), and is inhibited by iodoacetate,
fluoride, azide (115), and dinitrophenol (128b).
It has been reported (115-117, 128b, 132-135c) that yeasts, molds,
and bacteria contain both a "soluble fraction" and an "insoluble fraction" of polyphosphates regardless of growth conditions. These fractions have been further distinguished from each other by their metabolic behavior. The amount of the "insoluble fraction" was reduced
during nucleic acid synthesis (115, I34-J36); this was followed by
the depletion of the "soluble" polyphosphate. P
32 -labeled orthophosphate was incorporated rapidly only into the "insoluble fraction." It
has been suggested recently (110, 118) that the "soluble fraction" is
composed of low molecular weight material on the basis of its physical
and chemical properties. In view of the noninterconversion of the two
fractions and the above metabolic differences, it appears possible that
they are formed by independent mechanisms (HO).
Some evidence has been obtained that the formation of polyphosphates by yeast (137-139a) is the result of Reaction 39, catalyzed by
"metaphosphate kinase":
zATP + (P0 3 )n ^ zADP + (P0 3 )n + *
(39)
Kornberg et al. (110) have studied this reaction more extensively
with a purified enzyme from Escherichia colt. These investigators found
that the reaction yielded trichloracetic acid-insoluble material, formed
by polymerization of the terminal phosphate of ATP. Lower molecular
weight compounds were not produced; thus, it is possible that E. coli
has only one of the two polyphosphate-forming mechanisms suggested
for yeast. The product also: (a) induced metachromasy; (b) was not
dialyzable; (c) formed an acid-insoluble complex with protein; (d) was
labile to acid and base; (e) was bound firmly by anion exchange
resins; and (/) was resistant to nucleases. Furthermore, this enzyme
could utilize PP in place of ATP in Reaction 39, although at a slower
rate (50). The pyrophosphate reaction is shown in Eq. 40.
PP + (P0 3 )n ^± P t · + (PO3W1
(40)
It is possible that Reaction 40 could also occur in yeast, thereby accounting for the rapid incorporation of P
32 -labeled Pi into the "insoluble fraction."
A further study (140) of the polyphosphate-synthesizing enzyme
from E. coli showed that polyphosphate, prepared by chemical or enzymatic synthesis, may be utilized in the quantitative phosphorylation
F. M. HUENNEKENS AND H. R. WHITELEY
in fact, highly polymerized polyphosphate (110). The formation of
"volutin" by yeast and bacteria requires an oxidizable substrate, phosphate, and potassium ions (133), and is inhibited by iodoacetate,
fluoride, azide (115), and dinitrophenol (128b).
It has been reported (115-117, 128b, 132-135c) that yeasts, molds,
and bacteria contain both a "soluble fraction" and an "insoluble fraction" of polyphosphates regardless of growth conditions. These fractions have been further distinguished from each other by their metabolic behavior. The amount of the "insoluble fraction" was reduced
during nucleic acid synthesis (115, I34-J36); this was followed by
the depletion of the "soluble" polyphosphate. P
32 -labeled orthophosphate was incorporated rapidly only into the "insoluble fraction." It
has been suggested recently (110, 118) that the "soluble fraction" is
composed of low molecular weight material on the basis of its physical
and chemical properties. In view of the noninterconversion of the two
fractions and the above metabolic differences, it appears possible that
they are formed by independent mechanisms (HO).
Some evidence has been obtained that the formation of polyphosphates by yeast (137-139a) is the result of Reaction 39, catalyzed by
"metaphosphate kinase":
zATP + (P0 3 )n ^ zADP + (P0 3 )n + *
(39)
Kornberg et al. (110) have studied this reaction more extensively
with a purified enzyme from Escherichia colt. These investigators found
that the reaction yielded trichloracetic acid-insoluble material, formed
by polymerization of the terminal phosphate of ATP. Lower molecular
weight compounds were not produced; thus, it is possible that E. coli
has only one of the two polyphosphate-forming mechanisms suggested
for yeast. The product also: (a) induced metachromasy; (b) was not
dialyzable; (c) formed an acid-insoluble complex with protein; (d) was
labile to acid and base; (e) was bound firmly by anion exchange
resins; and (/) was resistant to nucleases. Furthermore, this enzyme
could utilize PP in place of ATP in Reaction 39, although at a slower
rate (50). The pyrophosphate reaction is shown in Eq. 40.
PP + (P0 3 )n ^± P t · + (PO3W1
(40)
It is possible that Reaction 40 could also occur in yeast, thereby accounting for the rapid incorporation of P
32 -labeled Pi into the "insoluble fraction."
A further study (140) of the polyphosphate-synthesizing enzyme
from E. coli showed that polyphosphate, prepared by chemical or enzymatic synthesis, may be utilized in the quantitative phosphorylation