Phang J M, Downing S J, Yeh G C, Smith R J, Williams J A, Hagedorn C H
J Cell Physiol. 1982 Mar;110(3):255-61. doi: 10.1002/jcp.1041100306.
delta 1-Pyrroline-5-carboxylic acid, an intermediate in the interconversions of proline, ornithine, and glutamate, is a potent stimulator of glucose oxidation through the hexosemonophosphate-pentose pathway. The effect is observed in cultured human fibroblasts, Chinese hamster ovary cells (CHO-K1), and rabbit kidney cells (LLC-RK1). In human fibroblasts, the magnitude of the stimulation of the hexosemonophosphate-pentose pathway is dependent on the concentration of added pyrroline-5-carboxylate and the effect is observed over a wide range of glucose concentrations. The mechanism of the effect is related to the generation of oxidizing potential in the form of NADP+ by pyrroline-5-carboxylate reductase concomitant with the conversion of pyrroline-5-carboxylate to proline. In LLC-RK1 cells, a cell line unique in having proline oxidase activity, proline also stimulated hexosemonophosphate-pentose pathway activity. Although pyrroline-5-carboxylate markedly stimulated the hexosemonophosphate-pentose pathway, it has no effect on glucose metabolism in the Embden-Meyerhof pathway or the tricarboxylic acid cycle. Since the hexosemonophosphate-pentose pathway is a source of ribose-5-phosphate, the precursor of phosphoribosyl pyrophosphate, the effect of pyrroline-5-carboxylate on the hexosemonophosphate-pentose pathway may link amino acid and nucleic acid metabolism.
δ1-吡咯啉-5-羧酸是脯氨酸、鸟氨酸和谷氨酸相互转化过程中的一种中间体，它是通过磷酸己糖-戊糖途径促进葡萄糖氧化的有效刺激物。在培养的人成纤维细胞、中国仓鼠卵巢细胞（CHO-K1）和兔肾细胞（LLC-RK1）中观察到了这种效应。在人成纤维细胞中，磷酸己糖-戊糖途径的刺激程度取决于添加的吡咯啉-5-羧酸盐的浓度，并且在很宽的葡萄糖浓度范围内都能观察到这种效应。其作用机制与吡咯啉-5-羧酸盐还原酶将吡咯啉-5-羧酸盐转化为脯氨酸的过程中伴随产生的以NADP⁺形式存在的氧化电位有关。在LLC-RK1细胞中，该细胞系具有脯氨酸氧化酶活性，脯氨酸也能刺激磷酸己糖-戊糖途径的活性。虽然吡咯啉-5-羧酸盐能显著刺激磷酸己糖-戊糖途径，但它对糖酵解途径或三羧酸循环中的葡萄糖代谢没有影响。由于磷酸己糖-戊糖途径是磷酸核糖焦磷酸的前体5-磷酸核糖的来源，吡咯啉-5-羧酸盐对磷酸己糖-戊糖途径的影响可能将氨基酸代谢和核酸代谢联系起来。
