150
F. M. HUENNEKENS AND H. R. WHITELEY
with purified arginine phosphokinase (340, 350, 353) or arginase (340).
A simple colorimetric assay for arginine after hydrolysis of tissue extracts has also been widely used as a measure of phosphoarginine (343,
348, 354). Phosphoarginine or free arginine may be separated and
identified by paper chromatography (347-348a, 354).
Studies of the distribution of phosphoguanidoacetate, phosphoguanidotaurine, and phosphoguanidoethylserylphosphate in animal tissues
have depended on preliminary fractionation of extracts followed by
paper chromatography (105, 328-333, 341, 349). The nonphosphorylated
guanidine compounds can also be separated chromatographically (355)
or identified by reaction with the specific phosphokinases (333, 338,
356). After prolonged acid hydrolysis of phosphoguanidoethylserylphosphate, guanidoethylserylphosphate, guanidoethylphosphate, guanidoethanol, phosphate, and serine can be detected by paper chromatography (105).
b. Biosynthesis. Phosphocreatine and phosphoarginine are formed
by the ATP-dependent phosphorylation of creatine and arginine as
shown in Reactions 63 and 64:
Creatine + ATP ;=± Phosphocreatine + ADP
(63)*
Arginine + ATP ^± Phosphoarginine + ADP
(64)
The distribution of the specific kinases mediating these reactions is
correlated with the accumulation of the specific N-phosphate compound
in a given tissue (342, 357). The properties of creatine phosphokinase
have been described in considerable detail (345a, 358-361). The enzyme
has been crystallized (362, 363), and studies have been made of the
kinetics of the reaction (46, 364, 365). Arginine phosphokinase has also
been purified and its properties, especially the interactions with metal
ions (365a), have been determined (353, 366). Crystallization of the
enzyme has been reported (367, 367a).
Invertebrates whose tissues do not contain phosphocreatine either
(a) do not possess the enzymes necessary for methylation of guanidoacetate to creatine, (b) do not contain guanidoacetate, or (c) lack
both methylation enzymes and methyl acceptor (368, 369). Conversely,
invertebrate tissues having phosphocreatine also contain free guanidoacetate and are able to methylate this compound at the expense of
either active methionine, betaine, or choline (369).
Studies have been made of the properties and kinetics of phosphokinases (338, 356, 365a, 366, 370) functioning in the synthesis of phos* The direct phosphorylation of creatine by 1,3-diphosphogly cerate has been
reported recently (356a).
F. M. HUENNEKENS AND H. R. WHITELEY
with purified arginine phosphokinase (340, 350, 353) or arginase (340).
A simple colorimetric assay for arginine after hydrolysis of tissue extracts has also been widely used as a measure of phosphoarginine (343,
348, 354). Phosphoarginine or free arginine may be separated and
identified by paper chromatography (347-348a, 354).
Studies of the distribution of phosphoguanidoacetate, phosphoguanidotaurine, and phosphoguanidoethylserylphosphate in animal tissues
have depended on preliminary fractionation of extracts followed by
paper chromatography (105, 328-333, 341, 349). The nonphosphorylated
guanidine compounds can also be separated chromatographically (355)
or identified by reaction with the specific phosphokinases (333, 338,
356). After prolonged acid hydrolysis of phosphoguanidoethylserylphosphate, guanidoethylserylphosphate, guanidoethylphosphate, guanidoethanol, phosphate, and serine can be detected by paper chromatography (105).
b. Biosynthesis. Phosphocreatine and phosphoarginine are formed
by the ATP-dependent phosphorylation of creatine and arginine as
shown in Reactions 63 and 64:
Creatine + ATP ;=± Phosphocreatine + ADP
(63)*
Arginine + ATP ^± Phosphoarginine + ADP
(64)
The distribution of the specific kinases mediating these reactions is
correlated with the accumulation of the specific N-phosphate compound
in a given tissue (342, 357). The properties of creatine phosphokinase
have been described in considerable detail (345a, 358-361). The enzyme
has been crystallized (362, 363), and studies have been made of the
kinetics of the reaction (46, 364, 365). Arginine phosphokinase has also
been purified and its properties, especially the interactions with metal
ions (365a), have been determined (353, 366). Crystallization of the
enzyme has been reported (367, 367a).
Invertebrates whose tissues do not contain phosphocreatine either
(a) do not possess the enzymes necessary for methylation of guanidoacetate to creatine, (b) do not contain guanidoacetate, or (c) lack
both methylation enzymes and methyl acceptor (368, 369). Conversely,
invertebrate tissues having phosphocreatine also contain free guanidoacetate and are able to methylate this compound at the expense of
either active methionine, betaine, or choline (369).
Studies have been made of the properties and kinetics of phosphokinases (338, 356, 365a, 366, 370) functioning in the synthesis of phos* The direct phosphorylation of creatine by 1,3-diphosphogly cerate has been
reported recently (356a).