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פותח על ידי קלירמאש פתרונות בע"מ -
Enzymes of ecdysteroid 3-epimerization in midgut cytosol of Manduca sexta: pH optima cosubstrate kinetics, and sodium chloride effect
Year:
1991
Source of publication :
Insect Biochemistry
Authors :
סבובודה, ג'יימס
;
.
Volume :
21
Co-Authors:
Weirich, G.F., Insect Hormone Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Thompson, M.J., Insect Hormone Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Svoboda, J.A., Insect Hormone Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Facilitators :
From page:
65
To page:
71
(
Total pages:
7
)
Abstract:
Five enzyme activities in midgut cytosol of Manduca sexta last instar larvae are potentially involved in the interconversion of 3β-hydroxyecdysteroids, 3-oxoecdysteroids, and 3α-hydroxyecdysteroids. A Sephadex G-25-filtered high-speed supernatant was used to determine some of the characteristics of the corresponding enzymes. The pH optima of ecdysone oxidase and NADH-dependent 3-oxoecdysteroid 3α-reductase were 7.5, the pH of the midgut cytosol was 7.9. The apparent kinetic parameters for the NADH-dependent 3α-reductase were Km (for NADH) = 80.8 ± 10.8 μM and Vmax = 0.58 ± 0.30 nmol/min/mg protein, and for the NADPH-dependent 3-oxoecdysteroid 3β-reductase, Km (for NADPH) = 19.3 ± 2.5 μM and Vmax = 4.39 ± 0.40 nmol/min/mg protein. NAD+ and NADP+ inhibited the enzymatic 3-oxoecdysteroid reductions, but the reactions were not reversible (i.e. no conversion of ecdysone or 3-epiecdysone to 3-dehydroecdysone). Sodium chloride (0.2 M) inhibited the 3α-reductase activity with NADH and strongly increased the 3α-reductase activity with NADPH. © 1991.
Note:
Related Files :
3-oxoecdysteroid 3-reductase
3α-hydroxyecdysteroid
3β-hydroxyecdysteroid
Manduca sexta
midgut
NADH
עוד תגיות
תוכן קשור
More details
DOI :
10.1016/0020-1790(91)90065-M
Article number:
Affiliations:
Database:
סקופוס
Publication Type:
מאמר
;
.
Language:
אנגלית
Editors' remarks:
ID:
28698
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:41
Scientific Publication
Enzymes of ecdysteroid 3-epimerization in midgut cytosol of Manduca sexta: pH optima cosubstrate kinetics, and sodium chloride effect
21
Weirich, G.F., Insect Hormone Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Thompson, M.J., Insect Hormone Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Svoboda, J.A., Insect Hormone Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States
Enzymes of ecdysteroid 3-epimerization in midgut cytosol of Manduca sexta: pH optima cosubstrate kinetics, and sodium chloride effect
Five enzyme activities in midgut cytosol of Manduca sexta last instar larvae are potentially involved in the interconversion of 3β-hydroxyecdysteroids, 3-oxoecdysteroids, and 3α-hydroxyecdysteroids. A Sephadex G-25-filtered high-speed supernatant was used to determine some of the characteristics of the corresponding enzymes. The pH optima of ecdysone oxidase and NADH-dependent 3-oxoecdysteroid 3α-reductase were 7.5, the pH of the midgut cytosol was 7.9. The apparent kinetic parameters for the NADH-dependent 3α-reductase were Km (for NADH) = 80.8 ± 10.8 μM and Vmax = 0.58 ± 0.30 nmol/min/mg protein, and for the NADPH-dependent 3-oxoecdysteroid 3β-reductase, Km (for NADPH) = 19.3 ± 2.5 μM and Vmax = 4.39 ± 0.40 nmol/min/mg protein. NAD+ and NADP+ inhibited the enzymatic 3-oxoecdysteroid reductions, but the reactions were not reversible (i.e. no conversion of ecdysone or 3-epiecdysone to 3-dehydroecdysone). Sodium chloride (0.2 M) inhibited the 3α-reductase activity with NADH and strongly increased the 3α-reductase activity with NADPH. © 1991.
Scientific Publication
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