Evidence for a Hybrid Ping Pong-Semirandom Mechanism for Human Jejunal Glutathione Disulfide Reductase

Authors : Nazmi Özer And İzzet Hamdi ÖĞÜŞ

Pages : 55-61

View : 19 | Download : 6

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Initial rate versus substrate concentration, [S], profiles insert ignore into journalissuearticles values(at pH 7.4, 37oC); for human jejunal glutathione disulfide reductase indicated partial substrate inhibition by GSSG at fixed [NADPH] \le 40 m M. Saturation by NADPH assumed an increasingly sigmoidal character at fixed [GSSG] \ge 20 m M. The results were interpreted in terms of a hybrid ping pong-semirandom mechanism proceeding through both E.NADPH insert ignore into journalissuearticles values(ping pong pathway); and E.GSSG insert ignore into journalissuearticles values(ordered pathway); complexes. When Vinsert ignore into journalissuearticles values(apparent); versus [GSSG] and [NADPH] were plotted, hyperbolic curves were obtained. Plotting 1/Vminsert ignore into journalissuearticles values(apparent); versus 1/[NADPH] and 1/[GSSG] yielded two lines with different slopes but intersecting at the same point on the y axis. A value of 26.3 U/ml was calculated for Vm, and Km values of 25 and 71 m M were determined for NADPH and GSSG, respectively.
Keywords : Glutathione disulfide reductase, ping pong semirandom mechanism, human jejunum