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Effect of L-malate on pyruvate dehydrogenase activity of spermatozoa
N M Gerez de Burgos1, F Gallina, C Burgos
1Cátedra de Quimica Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Argentina.
Abstract:
Presence of L-malate (from 0.5 to 4 mM concentrations) in the medium produces a marked increment of pyruvate consumption by the special type of mitochondria found in the middle piece of spermatozoa (sperm-type mitochondria, STM). Pyruvate uptake by liver mitochondria is not increased by malate. A comparative study on pyruvate dehydrogenase (PDH) of STM and liver mitochondria from mouse, rat, and rabbit showed that 2 mM L-malate does not modify significantly the activity of liver PDH, while it increases markedly that of spermatozoal PDH in the three species. The differential sensitivity to L-malate appears to be a peculiar regulatory property of the PDH complex in the gametes, which contains at least one component (E1, pyruvate decarboxylase, EC 1.2.4.1) known to be a sperm-specific isozyme.