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Ecotoxicological information

Additional ecotoxological information

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Administrative data

Endpoint:
additional ecotoxicological information
Type of information:
other: Literature data
Adequacy of study:
other information
Study period:
1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Literature data

Data source

Reference
Reference Type:
publication
Title:
Metabolism of Glyoxylate, the end product of purin degradation in liver peroxisomes of fresh water fish.
Author:
Sakuraba H., Fujiwara S., Noguchi T.
Year:
1996
Bibliographic source:
Biochem. Biophy. Res. Com., 229, 603-606.

Materials and methods

Principles of method if other than guideline:
The aim of this study is to describe that in fresh water fish, hepatic alanine/glyoxylate aminotransferase is located both in the peroxisomes and in the mitochondria.
GLP compliance:
not specified
Type of study / information:
Glyoxylate in vitro metabolism: Fresh water fish

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Any other information on results incl. tables

The intracellular distribution of alanine:glyoxylate aminotransferase was examined by sucrose density gradient
centrifugation with the postnuclear fractions of 7 different fresh water fish livers.

In each case, the peroxisomes and mitochondria were separated; the peroxisomes, marked by catalase, were at a density of about 1.25 g/ml and the mitochondria, marked by glutamate dehydrogenase, at a density of about 1.18
 g/ml.
Acid phosphatase as the lysosomal marker was distributed over a broad density range with a peak of about 1.19 g/ml.

In prussian carp, alanine/glyoxylate aminotransferase activity was recovered in the peroxisomal and mitochondrial fractions with a minor activity in the soluble fraction.

Alanine/glyoxylate aminotransferase/catalase in the peroxisomal fraction is similar to that in the soluble fraction, and glutamate dehydrogenase as the mitochondrial
marker is not recovered in the soluble fraction, it is suggested that alanine/glyoxylate aminotransferase activity in the soluble fraction is from broken peroxisomes and not from broken mitochondria.

These results show that alanine/glyoxylate aminotransferase is located both in the peroxisomes and in the mitochondria.

The same results were obtained with livers of other fresh water fishes (gengor carp, pale chub, large mouth bass, sunfish, wataka and hasu).

Alanine/glyoxylate aminotransferase has been reported to be located both in the mitochondria and in the cytosol in marine fish liver. In contrast, alanine/glyoxylate aminotransferase was found to be located both in the peroxisomes and in the mitochondria in fresh water fish liver.

Applicant's summary and conclusion

Conclusions:
In marine fish liver, degradative enzymes able to convert purines to urate have been shown to be located in the cytosol and degradative enzymes able to convert urate to urea and glyoxylate in the peroxisomes.
The end products of purine degradation are urea and glyoxylate in fish.
Glyoxylate may be converted to glycine by alanine/glyoxylate aminotransferase for the reutilization of purine carbon.

The intracellular localization of the enzyme differs between fresh water fish and marine fish:
- Alanine/glyoxylate aminotransferase is located both in peroxisome and in the mitochondria of fresh water,
- In contrast, alanine/glyoxylate is located both in the mitochondria and in the cytosol in marine fish liver.