Stimulation of pyruvate dehydrogenase phosphatase activity by polyamines |
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Authors: | Z Damuni J S Humphreys L J Reed |
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Institution: | 1. Clayton Foundation Biochemical Institute The University of Texas at Austin, Austin, Texas 78712 USA;2. Department of Chemistry The University of Texas at Austin, Austin, Texas 78712 USA |
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Abstract: | Pyruvate dehydrogenase phosphatase requires Mg2+ or Mn2+, and its activity in the presence of Mg2+ is markedly stimulated by Ca2+. At saturating Mg2+ and Ca2+ concentrations, the polyamines spermine, spermidine and putrescine stimulated the activity of pyruvate dehydrogenase phosphatase 1.5- to 3-fold. Spermine was the most active of the polyamines. At a physiological concentration of Mg2+ (1 mM) and saturating Ca2+ concentration, the stimulation by 0.5 mM spermine was 4- to 5-fold, and at 0.3 mM Mg2+, the stimulation was 20- to 30-fold. In the absence of Mg2+ or Ca2+, spermine had no effect. These results suggest that a polybasic factor may be involved in the regulation of pyruvate dehydrogenase phosphatase activity. |
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