High control coefficient of transketolase in the nonoxidative pentose phosphate pathway of human erythrocytes: NMR, antibody, and computer simulation studies

• Published in: Biochemistry (Easton) Vol. 31; no. 51; pp. 12792 - 12798
• Main Authors: Berthon, Hilary A, Kuchel, Philip W, Nixon, Peter F
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 29.12.1992
• Subjects: Biological and medical sciences; Blotting, Western; Cell metabolism, cell oxidation; Cell physiology; Computer Simulation; erythrocytes; Erythrocytes - enzymology; Fundamental and applied biological sciences. Psychology; Humans; Immune Sera; Kinetics; Luminescent Measurements; Magnetic Resonance Spectroscopy; man; mathematical models; Molecular and cellular biology; N.M.R; Pentose Phosphate Pathway; Pentosephosphates - blood; Ribosemonophosphates - blood; Ribulosephosphates - blood; transketolase; Transketolase - blood; Transketolase - immunology; Human; Regulation(control); Enzymatic activity; Computer simulation; Enzyme; Transketolase; Pentose phosphate pathway; Red blood cell; NMR spectrometry; In vitro; Modeling
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00166a012

The degree of control exerted by transketolase over metabolite flux in the nonoxidative pentose phosphate pathway in human erythrocytes was investigated using transketolase antiserum to modulate the activity of that enzyme. 31P NMR enabled the simultaneous measurement of the levels of pentose phosphate pathway metabolites following incubation of hemolysates with ribose 5-phosphate. The variations in metabolic flux which occurred as the transketolase activity of hemolysate samples was altered indicated that a high degree of control was exerted by transketolase. Investigations using transaldolase-depleted hemolysates showed that transaldolase exhibits a lesser degree of control over pathway flux. Experimental data were compared with simulations generated by a computer model encompassing the reactions of the classical nonoxidative pentose phosphate pathway. The sensitivity coefficients (also called "control strengths" or "flux-control coefficients") calculated from the computer simulations were 0.74 and 0.03 for transketolase and transaldolase, respectively.