Kiechle F L, Malinski H, Dandurand D M, McGill J B
Department of Clinical Pathology, William Beaumont Hospital, Royal Oak, MI 48072.
Mol Cell Biochem. 1990 Mar 27;93(2):195-206. doi: 10.1007/BF00226192.
The ability of polyamines and other cationic compounds including monoamines, amino acids, poly-L-arginine, poly-D-lysine and poly-L-lysine, to alter pyruvate dehydrogenase (PDH) activity in mitochondria from rat epididymal adipocytes was determined. PDH was assayed with the substrate [1-14C] pyruvate in the presence of 0.05 mM Ca2+ and Mg2+. Nine of the fourteen compounds tested at 0.1 mM caused a significant increase (procaine, 3-(beta-morpholinopropionyl) benzo [b]thiophene [VII], spermine, spermidine, putrescine, lysine and tryptophan) or decrease (poly-L-arginine, 3-(beta-piperidinopropionyl) benzo[b]thiophene) in PDH activity. None of these compounds nonenzymatically decarboxylated [1-14C] pyruvate to release 14CO2. NaF, a PDH phosphatase inhibitor, suppressed the stimulatory effects of those compounds tested: procaine, tryptophan, VII, spermine and spermidine. These results imply that these five compounds activate PDH activity through stimulation of the PDH phosphatase. When the Mg2+ concentration was increased from 0.05 to 4.5 mM, the stimulatory effect of spermine was increased, consistent with the finding by others that spermine lowers the Km of the enzyme for Mg2+. However, at Mg2+ concentrations greater than 0.3 mM, the stimulatory effect of VII was unaltered, procaine failed to alter PDH activity, lysine inhibited PDH activity, and poly-L-lysine stimulated PDH activity. Therefore, polyamines and other positively charged small molecules may be physiologic regulators of PDH activity.
测定了多胺及其他阳离子化合物（包括单胺、氨基酸、聚-L-精氨酸、聚-D-赖氨酸和聚-L-赖氨酸）改变大鼠附睾脂肪细胞线粒体中丙酮酸脱氢酶（PDH）活性的能力。在存在0.05 mM Ca2+和Mg2+的情况下，用底物[1-14C]丙酮酸测定PDH活性。在0.1 mM浓度下测试的14种化合物中有9种导致PDH活性显著增加（普鲁卡因、3-(β-吗啉丙酰基)苯并[b]噻吩[VII]、精胺、亚精胺、腐胺、赖氨酸和色氨酸）或降低（聚-L-精氨酸、3-(β-哌啶丙酰基)苯并[b]噻吩）。这些化合物均未非酶促地使[1-14C]丙酮酸脱羧释放14CO2。PDH磷酸酶抑制剂氟化钠抑制了所测试的那些化合物（普鲁卡因、色氨酸、VII、精胺和亚精胺）的刺激作用。这些结果表明这五种化合物通过刺激PDH磷酸酶来激活PDH活性。当Mg2+浓度从0.05 mM增加到4.5 mM时，精胺的刺激作用增强，这与其他人发现精胺降低该酶对Mg2+的Km值的结果一致。然而，在Mg2+浓度大于0.3 mM时，VII的刺激作用未改变，普鲁卡因未能改变PDH活性，赖氨酸抑制PDH活性，而聚-L-赖氨酸刺激PDH活性。因此，多胺和其他带正电荷的小分子可能是PDH活性的生理调节剂。
