The purification and properties of arginine phosphokinase

Abstract

A method is described for the isolation of a highly active preparation of arginine phosphokinase from the tail muscle of the sea crayfish (Jasus verreauxi). The purity was estimated to be 67-80%. The enzyme had a pH optimum of 6.6-7 and 8.4-8.5 in the forward and reverse reactions respectively, as expressed by the equation: Phosphoarginine + adenosine diphosphatearginine + adenosine triphosphate. Mn2+ and Mg2+ ions activated the enzyme in both the forward and reverse reactions. There was no activation by Ca2+ ions. The -SH nature of the enzyme was established as a result of the inhibition by iodoacetate, p-chloromer-curibenzoate, etc. There was also inhibition by ethylenediaminetetra-acetic acid and 2:4-dinitrophenol. The enzyme phosphorylated homo-arginine and canavanine. There was no phosphorylation of agmatine, argininic acid, [delta]-guanido-n-valeric acid, [alpha]-carbamidoarginine, citrul-line, creatine, negmine, glycocyamine, [beta]-guanidopropionic acid or taurocyamine. Adenosine 5[image]-phosphate could not act as a phosphate acceptor in the forward reaction. Inosine triphosphate or adenosine diphosphate could not replace adenosine triphosphate in the reverse reaction.