Glyoxylic acid

Biotransformation and kinetics

Administrative data

Endpoint:

biotransformation and kinetics

Type of information:

other: Literature data

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Literature data

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Comparative biochemistry of the glyoxylate cycle

Author:

Cioni M. Pinzauti G., Vanni P.

Year:

1981

Bibliographic source:

Comp. Biochem. Physiol. 70B, 1-26

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1957

Materials and methods

GLP compliance:

not specified

Type of medium:

plant

Test material

Test material information

Constituent 1

Reference substance name:

Glyoxylic acid

EC Number:

206-058-5

EC Name:

Glyoxylic acid

Cas Number:

298-12-4

Molecular formula:

C2H2O3

IUPAC Name:

2-oxoacetic acid

Results and discussion

Any other information on results incl. tables

Glyoxylic acid is an important metabolite in the plants.

Glyoxylic acid-cycle is a shunt of the Krebs cycle in the plants and some procaryotes cells.
It was studied by Kornberg and Krebs.

In a paper written in 1980, Cioni and al. described the enzymatic system for the biotransformation of isocitrate in malate and succinate.
Isocitratelyase catalyses the aldolic cutting of isocitrate in succinate and glyoxylate. Then, maltate-synthetase
transforms glyoxylate by adding COA.

Glyoxylate cycle is already a shunt of the Krebs'cycle, becoming from and going to isocitrate.

Glyoxylic acid is found in number of plants having the C4 route, essentially in germinative or growing phases in which lipids are transformed in glucides.

In an other hand, enlightened plants use oxygen and excrete CO2 (photorespiration).

Glycolate, substrate of photorespiration, becomes from 1,5-diphospho-ribulose, which is metabolized in
phosphoglycolate and then in glyoxylic acid by oxidation.

This reaction is catalyzed by an oxygenase, ribulose diphosphate-1,5 carboxylase.

Phosphoglycolate obtained by this metabolic route is hydrolyzed in glycolate by a specific phosphatase. Then glycolate is oxidized, in the peroxizomes, in glyoxylate by glycolate-oxydase. Glyoxylate is then easily transformed in glycine.

The plants not having the C4 metabolisation route, loss 25 to 50 % of their carbon due to the photorespiration, essentially in plants living under temperate climates.