Biliverdin Reductase from the Liver of Atlantic Salmon (Salmo salar)

Y. Q. Xu and Z. K. Ding^*

Key Laboratory of Marine Biology, Shangtou University, Guangdong 515063, People's Republic of China

University of Toronto, 711-35 Charles Street West, Toronto, ON, M4Y 1R6, Canada; E-mail: ZhaokunD@hotmail.com

National Research Council of Canada, NS, Canada H3B 3Z1

^* To whom correspondence should be addressed.

Received October 21, 2002; Revision received December 13, 2002

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Biliverdin reductase was characterized and purified from the liver of Atlantic salmon (Salmo salar) using a novel enzymatic staining method. The properties of the enzyme are quite different from those of mammals. The purified enzyme is a monomeric protein with a molecular weight of approximately 68 kD and an isoelectric point of around 3.8. The enzyme can utilize both NADH and NADPH as coenzyme, but the kinetic properties of the NADH-dependent and the NADPH-dependent enzyme activities are different: K_m value for biliverdin IXalpha is 0.6 µM in the NADPH system, while it is 6.8 µM in the NADH system. Both enzyme activities are inhibited by excess biliverdin IXalpha, but the NADPH-dependent enzyme activity is far more susceptible. The optimum pH for activity is 5.5 with NADPH and 6.0 with NADH. The optimum reaction temperature is 35°C.

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KEY WORDS: biliverdin reductase, biliverdin, bilirubin, heme degradation, salmon

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