148
F. M. HUENNEKENS AND H. R WHITELEY
been reported (321a) to carry out Reaction 61; reversal of this reaction
using chemically synthesized phosphoryl-CoA was also indicated.
6. Amidine Phosphates: Creatine, Arginine, and
Other Guanidophosphates
a. Preparation and Identification. A labile N-phosphate compound
was first discovered by Eggleton and Eggleton (322, 323) in mammalian muscle, and was subsequently isolated and identified as phosphocreatine by Fiske and SubbaRow (324, 325). Phosphoarginine was
isolated and identified from extracts of invertebrate muscle by Meyerhof
and Lohmann (326). Three additional "energy-rich" N-phosphate compounds have been encountered more recently (327-330): i.e., phosphoguanidoacetate, phosphoguanidotaurine, and phosphoguanidoethylserylphosphate ("lombricine"). The structures of these latter compounds
were elucidated after isolation in crystalline form from tissues of certain
species of Annelida, Sipunculoidea, and Nemertea (105, 327-333). None
of the above amidine phosphates is found in plants (334) or in bacteria (335). Formulas of the 5 compounds, often termed "phosphagens,"
are given in Fig. 10.
Phosphocreatine, phosphoguanidoacetate, and phosphoguanidotaurine may be synthesized by phosphorylation with POCl 3 of creatine
(336, 337), guanidoacetate (331, 338, 339), and guanidotaurine (331,
338, 339). Phosphoarginine has not yet been synthesized, but can be
isolated from the muscle of the crayfish Jasus verreauxi (340, 340a).
Phosphoguanidoethylserylphosphate has been synthesized recently
(340b), following the interesting discovery that the serine moiety has
the D-configuration (340c).
A detailed discussion of the methods for identifying these compounds is presented in the comprehensive review on amidine phosphates
by Ennor and Morrison (341). In much of the early work, identification
of phosphocreatine (342, 343) and phosphoarginine (344) was based
on the lability of the phosphate bond in acid. Phosphocreatine was estimated directly by the Fiske-SubbaRow method for Pi, after an initial
precipitation of P{ with Ca
2+ ; phosphoarginine required more prolonged
hydrolysis in acid. In tissues containing both phosphoarginine and phosphocreatine, the two compounds were distinguished by differences in
rates of hydrolysis in acid molybdate (343). These procedures have
been criticized (345) because of the difficulty in quantitatively removing P { by precipitation with Ca
2+ , and because labile phosphate compounds other than phosphocreatine and phosphoarginine may be hydrolyzed under the conditions of testing.
More recently, free creatine resulting from acid hydrolysis of phos-
F. M. HUENNEKENS AND H. R WHITELEY
been reported (321a) to carry out Reaction 61; reversal of this reaction
using chemically synthesized phosphoryl-CoA was also indicated.
6. Amidine Phosphates: Creatine, Arginine, and
Other Guanidophosphates
a. Preparation and Identification. A labile N-phosphate compound
was first discovered by Eggleton and Eggleton (322, 323) in mammalian muscle, and was subsequently isolated and identified as phosphocreatine by Fiske and SubbaRow (324, 325). Phosphoarginine was
isolated and identified from extracts of invertebrate muscle by Meyerhof
and Lohmann (326). Three additional "energy-rich" N-phosphate compounds have been encountered more recently (327-330): i.e., phosphoguanidoacetate, phosphoguanidotaurine, and phosphoguanidoethylserylphosphate ("lombricine"). The structures of these latter compounds
were elucidated after isolation in crystalline form from tissues of certain
species of Annelida, Sipunculoidea, and Nemertea (105, 327-333). None
of the above amidine phosphates is found in plants (334) or in bacteria (335). Formulas of the 5 compounds, often termed "phosphagens,"
are given in Fig. 10.
Phosphocreatine, phosphoguanidoacetate, and phosphoguanidotaurine may be synthesized by phosphorylation with POCl 3 of creatine
(336, 337), guanidoacetate (331, 338, 339), and guanidotaurine (331,
338, 339). Phosphoarginine has not yet been synthesized, but can be
isolated from the muscle of the crayfish Jasus verreauxi (340, 340a).
Phosphoguanidoethylserylphosphate has been synthesized recently
(340b), following the interesting discovery that the serine moiety has
the D-configuration (340c).
A detailed discussion of the methods for identifying these compounds is presented in the comprehensive review on amidine phosphates
by Ennor and Morrison (341). In much of the early work, identification
of phosphocreatine (342, 343) and phosphoarginine (344) was based
on the lability of the phosphate bond in acid. Phosphocreatine was estimated directly by the Fiske-SubbaRow method for Pi, after an initial
precipitation of P{ with Ca
2+ ; phosphoarginine required more prolonged
hydrolysis in acid. In tissues containing both phosphoarginine and phosphocreatine, the two compounds were distinguished by differences in
rates of hydrolysis in acid molybdate (343). These procedures have
been criticized (345) because of the difficulty in quantitatively removing P { by precipitation with Ca
2+ , and because labile phosphate compounds other than phosphocreatine and phosphoarginine may be hydrolyzed under the conditions of testing.
More recently, free creatine resulting from acid hydrolysis of phos-