Studies on the interaction of metal ions with pyruvate kinase from Ehrlich ascites-tumour cells and from rabbit muscle

Publisher Website
Google Scholar
Abstract
Pyruvate kinase (ATP [adenosine triphosphate]-pyruvate phospho-transferase, EC 2.7.1.40) from Ehrlich ascites-tumor cells was purified approximately fivefold by chromatography on DEAE-cellulose. The enzyme was shown to have an absolute requirement for one uni-valent and for one bivalent metal ion. The univalent metal Ion re?quirements were satisfied by K+, Rb+ or NH4+; Na+ and Cs+ were weak activators but Li+ was inactive. Ca2+ exhibited "non-competi?tive" and "apparent competitie" effects in relation to the K+ activa?tion. The bivalent metal ion requirements were satisfied by Mg2+, Mn2+ or Co2+; Ba2+, Sr2+, Ca2+, Ni2+, Be2+ and Cu2+ were inactive. Mn2+ and Co2+ were better activators than Mg2+. The bivalent metal ion requirements of purified pyruvate kinase from rabbit muscle were satisfied by Mg2+, Mn2+, Co2+ and to a smaller extent by Ni2+. Mn2+ and Co2+ were better activators than Mg2+. Ca2+ competitively in?hibited the activation by Mg2+, Mn2+ and Co2+ for both the tumor and rabbit enzymes. It is concluded that there are no significant differences in metal ion specificity between the tumor and rabbit enzymes. The possible role of metal ions in regulating enzymic and metabolic activities is considered further.