Oxidation of glycine by Phaseolus leghaemoglobin with associated catabolic reactions at the haem

Leghaemoglobin from the root nodules of kidney bean (Phaseolus vulgaris) reacts in alkaline glycine solutions as a glycine oxidase in a reaction that may also be regarded as a coupled oxidation. Leghaemoglobin is reduced to the ferrous form by glycinate, the oxygen complex is formed, and finally the...

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Bibliographic Details
Published in:Biochemical journal 1978-11, Vol.176 (2), p.351-358
Main Author: Lehtovaara, P
Format: Article
Language:English
Subjects:
Carboxypeptidases - pharmacology
Fabaceae - metabolism
Glycine - metabolism
Glyoxylates - metabolism
Heme - metabolism
Hemeproteins - metabolism
Hydrogen Peroxide - metabolism
Kinetics
Leghemoglobin - metabolism
Oxidation-Reduction
Plants - metabolism
Plants, Medicinal
Superoxide Dismutase - pharmacology
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Summary:Leghaemoglobin from the root nodules of kidney bean (Phaseolus vulgaris) reacts in alkaline glycine solutions as a glycine oxidase in a reaction that may also be regarded as a coupled oxidation. Leghaemoglobin is reduced to the ferrous form by glycinate, the oxygen complex is formed, and finally the haem is attacked to yield a green reaction product. Glycine is simultaneously oxidized to glyoxylate, and hydrogen peroxide is generated. The initial velocity of the formation of the green product is proportional to the concentrations of leghaemoglobin and glycine, and the optimum pH for the reaction is 10.2. The green product is not formed if carbon monoxide, azide of imidazole is bound to the haem, whereas oxidation of glycine to glyoxylate is not inhibited by azide and not essentially by carbon monoxide. Haem breakdown is activated by digestion of leghaemoglobin by carboxypeptidase, and partly inhibited by catalase and superoxide dismutase.
ISSN:0264-6021
0306-3283
1470-8728
DOI:10.1042/bj1760351