Hexokinase, phosphofructokinase and pyruvate kinase isozymes in lymphocyte subpopulations

Abstract

SummaryIn order to study the three regulator enzymes of glycolysis, hexokinase (HK). phosphofructokinase (PFK) and pyruvate kinase (PK), in relation to lymphocyte nlaturatjon, lymphocytes of different origin were investigated. Lymphocytes from bone marrow, thymus, cord blood, adult peripheral blood and mitogen-stimulated lymphocytes were investigated. The enzyme activities were determined and the isozyme patterns were studied by means of electrophoresis, kinetic measurements and immunoprecipitation.The young lymphocytes from bone marrow and the mitogen-stimulated lymphocytes could be distinguished from the other lymphocytes by a higher residual HK activity in the presence of the inhibitor glucose-1,Gdiphosphate. Peripheral blood T lymphocytes differed from non-T lymphocytes in the PK isozymes distribution.All the cells contained PK type K, and the hybrid K,M. In T cells a smaller amount of the K isozyme was seen than in non-T cells. The PK residual activity in the presence of alanine was significantly higher in peripheral blood T cells than in non-T cells.Thymocytes are characterised by a larger amount of PFK M-subunits than peripheral blood T and non-T lymphocytes.The stimulation of PFK by the positive effector glucose-1,Gdiphosphate was higher in thymocytes than in the peripheral blood lymphocytes.

Reexamination of the Physiological Role of PykA in Escherichia coli Revealed that It Negatively Regulates the Intracellular ATP Levels under Anaerobic Conditions

“…There are three rate-limiting enzymes in glycolysis, i.e., hexokinase, phosphofructokinase, and pyruvate kinase, among which only pyruvate kinase is associated with ATP generation (13). Pyruvate kinase catalyzes the last step of glycolysis, converting phosphoenolpyruvate (PEP) into pyruvate.…”