אסיף מאגר המחקר החקלאי

Ecdysone oxidase and 3‐oxoecdysteroid reductases in Manduca sexta midgut: Kinetic parameters

Year:

1989

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Volume :

12

Co-Authors:

Weirich, G.F., Insect Hormone Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States
Thompson, M.J., Insect Hormone Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States
Svoboda, J.A., Insect Hormone Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States

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Abstract:

Ecdysone and 20‐hydroxyecdysone are converted to their 3‐epimers by enzymes in the midgut cytosol of Manduca sexta larvae. A partially purified cytosol preparation has been used to analyze the nature of and the interaction between these enzymes. The cytosol was shown to contain ecdysone oxidase, one or more 3‐oxoecdysteroid 3α‐reductase(s), and one or more 3‐oxoecdysteroid 3β‐reductase(s). The reductases reacted at different velocities with NADH and NADPH. With NADH, 3α‐reduction was the major reaction; with NADPH, 3β‐reduction was the major reaction. The apparent kinetic parameters for the enzymes support the assumed two‐step mechanism for the 3‐epimerization with a 3‐oxoecdysteroid as intermediate. Copyright © 1989 Wiley‐Liss, Inc.

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