Comparative Analysis of Malate Dehydrogenases of Drosophila melanogaster
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Biochemical Genetics, Vol: 10, Issue: 2, Page: 191
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- Biochemistry; Genetics and Genomics; Zoology
The malate dehydrogenases of D. melanogaster have been resolved into a cytoplasmic form (cMDH) and a mitochondrial matrix form (mMDH). Flies homozygous for allozyme variants exhibit isozymes of cMDH detected by starch gel electrophoresis and acrylamide gel isoelectric focusing. The basis of these isozymes was investigated, and the results suggest either conformational or epigenetic modification of isozymes. The probable structural gene for cMDH (Mdh-1) has been mapped genetically by allozyme variants to II-35 ± 3 and cytologically by monitoring gene dosage in segmental aneuploids to between 28D and 29F on II-L of the Drosophila salivary gland chromosome map. The structural gene for mMDH is neither identical to nor in the near chromosomal proximity of Mdh-1. Nevertheless, the two enzymes exhibit markedly similar properties with respect to (1) catalytic activity, (2) pH optima, (3) pH optimum shift in response to different ionic environments, and (4) molecular weight as determined by sucrose density gradient sedimentation.