Genetics and Molecular Biology (Jan 2008)

Soluble malate dehydrogenase of Geophagus brasiliensis (Cichlidae, Perciformes): isolated isoforms and kinetics properties

  • Maria Regina de Aquino-Silva,
  • Maria Luiza Barcellos Schwantes,
  • Flavia Simone Munin,
  • Arno Rudi Schwantes,
  • Silvana Pereira dos Santos

DOI
https://doi.org/10.1590/S1415-47572008000200029
Journal volume & issue
Vol. 31, no. 1
pp. 337 – 342

Abstract

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Kinetic properties and thermal stabilities of Geophagus brasiliensis skeletal muscle unfractionated malate dehydrogenase (MDH, EC 1.1.1.37) and its isolated isoforms were analyzed to examine a possible sMDH-B* locus duplication in a fixation process influenced by genetic drift. Two optimal pHs were detected: 7.5 for AB1 unfractionated muscle phenotype and its B1 isoform, and 8.0 for AB1B2 unfractionated muscle phenotype, A and B2 isoforms. While G. brasiliensis A isoform could be characterized as thermostable, the duplicated B isoform cannot be assumed as thermolabile. Km values for isolated B2 isoforms were 1.6 times lower than for B1. A duplication event in progress best explains the electrophoretic six-band pattern detected in G. brasiliensis, which would be caused by genetic drift.

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