The Kinetics and Mechanism of Action of Rabbit Muscle l-α-Glycerol Phosphate Dehydrogenase

1973 ◽  
Vol 1 (3) ◽  
pp. 663-665 ◽  
Author(s):  
PHILIP BENTLEY ◽  
F. MARK DICKINSON
Keyword(s):  
Mechanism Of Action ◽  
Kinetics And Mechanism ◽  
Rabbit Muscle ◽  
Glycerol Phosphate ◽  
Glycerol Phosphate Dehydrogenase

scholarly journals Direct transfer of NADH between alpha-glycerol phosphate dehydrogenase and lactate dehydrogenase: fact or misinterpretation?

1989 ◽  
Vol 86 (17) ◽  
pp. 6464-6468 ◽  
Author(s):  
D K Srivastava ◽  
P Smolen ◽  
G F Betts ◽  
T Fukushima ◽  
H O Spivey ◽  
...  
Keyword(s):  
Steady State ◽  
Lactate Dehydrogenase ◽  
Transfer Mechanism ◽  
Rabbit Muscle ◽  
Direct Transfer ◽  
Glycerol Phosphate ◽  
Steady State Kinetic ◽  
State Kinetic ◽  
Random Diffusion ◽  
Glycerol Phosphate Dehydrogenase

Following the criticism by Chock and Gutfreund [Chock, P.B. & Gutfreund, H. (1988) Proc. Natl. Acad. Sci. USA 85, 8870-8874], that our proposal of direct transfer of NADH between glycerol-3-phosphate dehydrogenase (alpha-glycerol phosphate dehydrogenase, alpha-GDH; EC 1.1.1.8) and L-lactate dehydrogenase (LDH; EC 1.1.1.27) was based on a misinterpretation of the kinetic data, we have reinvestigated the transfer mechanism between this enzyme pair. By using the "enzyme buffering" steady-state kinetic technique [Srivastava, D.K. & Bernhard, S.A. (1984) Biochemistry 23, 4538-4545], we examined the mechanism (random diffusion vs. direct transfer) of transfer of NADH between rabbit muscle alpha-GDH and pig heart LDH. The steady-state data reveal that the LDH-NADH complex and the alpha-GDH-NADH complex can serve as substrate for the alpha-GDH-catalyzed reaction and the LDH-catalyzed reaction, respectively. This is consistent with the direct-transfer mechanism and inconsistent with a mechanism in which free NADH is the only competent substrate for either enzyme-catalyzed reaction. The discrepancy between this conclusion and that of Chock and Gutfreund comes from (i) their incorrect measurement of the Km for NADH in the alpha-GDH-catalyzed reaction, (ii) inadequate design and range of the steady-state kinetic experiments, and (iii) their qualitative assessment of the prediction of the direct-transfer mechanism. Our transient kinetic measurements for the transfer of NADH from alpha-GDH to LDH and from LDH to alpha-GDH show that both are slower than predicted on the basis of free equilibration of NADH through the aqueous environment. The decrease in the rate of equilibration of NADH between alpha-GDH and LDH provides no support for the random-diffusion mechanism; rather, it suggests a direct interaction between enzymes that modulates the transfer rate of NADH. Thus, contrary to Chock and Gutfreund's conclusion, all our experimental data compel us to propose, once again, that NADH is transferred directly between the sites of alpha-GDH and LDH.

scholarly journals Mechanism of Action of Rabbit Muscle Phosphoglucomutase

1974 ◽  
Vol 249 (10) ◽  
pp. 3166-3169 ◽  
Author(s):  
Olov Wålinder ◽  
Jayant G. Joshi
Keyword(s):  
Mechanism Of Action ◽  
Rabbit Muscle
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