Isolation and characterization of tissue-specific isozymes of glucosephosphate isomerase from catfish and conger.

Mo, Y; Young, C D; Gracy, R W; Carter, N D; Dando, P R. 1975 Isolation and characterization of tissue-specific isozymes of glucosephosphate isomerase from catfish and conger.. The Journal of biological chemistry, 250 (17). 6747-55.

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Abstract/Summary

In teleosts glucosephosphate isomerase exists as two tissue-specific isozymes. Most tissues contain the more acidic liver-type isozyme, while white muscle contains the more basic isozyme; and a few tissues contain both the liver- and muscle-type isozymes as well as a hybird. The isozymes were isolated from catfish liver and muscle and from conger muscle and shown to be homogeneous by polyacrylamide gel electrophoresis, isoelectric focusing, analytical ultracentrifugation, and rechromatography. Both isozymes are of molecular weight 132,000 (S020,w = 7.0 S) and composed of two subunits of Mr approximately 65,000. The muscle and liver isozymes were shown to have distinct isoelectric points (catfish liver = 6.2; muscle = 7.0) and amino acid compositions. Tryptic peptide maps, after S-carboxymethylation and carbamylation, revealed several distinct differences in the primary structures of the isozymes. Although the isozymes could also be distinguished on the basis of their stabilities, most of their basic catalytic properties were found to be similar. A conger was obtained which was heterozygous for the variant allele at the muscle-glucosephosphate isomerase locus. A comparison of the variant conger muscle isozyme with the wild type revealed a single altered peptide, suggesting a point mutation. The structure-function studies, as well as the genetic studies, clearly establish that the two types of isozymes are of independent genetic origin.

Item Type: Publication - Article
Subjects: Ecology and Environment
Marine Sciences
Zoology
Divisions: Marine Biological Association of the UK > Other (MBA)
Depositing User: Professor Paul Dando
Date made live: 06 Jan 2022 15:59
Last Modified: 06 Jan 2022 15:59
URI: http://plymsea.ac.uk/id/eprint/9505

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