Inhibition of the pyruvate kinase of Helix pomatia L. By phospho‐L‐arginine Phosphorylation or a novel mechanism?

Apparent inhibition of pyruvate kinase by arginine phosphate a problem of kinetic studies on partially purified extracts

“…Due to the arginine kinase activity also present in the preparations used, ADP is converted into ATP which leads to a concomitant reduction of the pyruvate kinase reaction rate. As in [1][2][3][4] no evidence is offered to show that arginine kinase is not involved; we doubt its effect on pyruvate kinase.…”

“…Arginine phosphate could act either as a competitive inhibitor [1,2] or by phosphorylating or inducing a protein-protein interaction resulting in a decreased affinity for PEP [4]. In these studies the enzyme source was a crude extract [4], fractionated by ammonium sulphate, or partiallypurified by other standard protein isolation procedures [1,2].…”

“…Arginine phosphate could act either as a competitive inhibitor [1,2] or by phosphorylating or inducing a protein-protein interaction resulting in a decreased affinity for PEP [4]. In these studies the enzyme source was a crude extract [4], fractionated by ammonium sulphate, or partiallypurified by other standard protein isolation procedures [1,2]. This paper reports how arginine phosphate exhibits effects on pyruvate kinase examined in crude extracts of the adductor muscle of the sea mussel Mytilus edulis similar to those described [1][2][3][4].…”

“…In these studies the enzyme source was a crude extract [4], fractionated by ammonium sulphate, or partiallypurified by other standard protein isolation procedures [1,2]. This paper reports how arginine phosphate exhibits effects on pyruvate kinase examined in crude extracts of the adductor muscle of the sea mussel Mytilus edulis similar to those described [1][2][3][4].…”

Multiple control of Helix pomatia pyruvate kinase by high‐Mr modulators

“…However, the degree of inactivation (i.e., degree of FBP-sensitivity) varies from preparation to preparation. One finds preparation with a So.s(PEP) of several mM down to nearly the 'normal' K m-value of a FBPactivated PK, of 60-90/aM [7,8]. The Hill coefficient may vary from 1.8-1.0.…”