STUDIES WITH INHIBITORS OF THE GLYCOLYTIC ENZYME PHOSPHOGLYCERATE KINASE FOR POTENTIAL TREATMENT OF CARDIOVASCULAR AND RESPIRATORY DISORDERS

Inhibition of the glycolytic enzyme phosphoglycerate kinase (PGK) in e rythrocyte cells could provide a method of treatment for cardiovascula r and respiratory disorders. The product of the reaction catalysed by PGK, 1,3-diphosphoglycerate, is converted by another enzyme in erythro cytes to 2,3-diphosphoglycerate, which is an allosteric effector of ha emoglobin. For this reason, a series of fluoro-phosphonate inhibitors have been tested for their potency in detailed inhibition kinetic expe riments with yeast PGK. The results were analysed by Lineweaver-Burk a nd Dixon plots and K-i values obtained. Two fluorophosphonates were fo und to be inhibitory and both have an electron rich mid-chain function ality, which is thought to provide electrons for hydrogen bonding to r esidues in the triose binding site of the enzyme. It is postulated tha t either the fluorine or mid-chain moieties of the analogues are bindi ng to Asp23 and Asn25 residues in the so called 'basic patch' area of the triose site. These residues are shown to bind to the D-hydroxyl mo iety on the C2 of the true substrate, 3-phosphoglycerate, in the high- resolution crystal structure of pig muscle PGK co-crystallized with 3- phosphoglycerate.