The inhibitory impact of glutathione (GSH) and ascorbic acid (vitamin C) compounds on glucose-6-phosphate dehydrogenase (G6PD) enzyme purified from sheep liver

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme with many essential biochemical functions. However, in various cancer diseases, increased activity of G6PD causes cancer cells to grow, so G6PD inhibitors have become a significant area of research in cancer treatment. Here, G6PD was purified 4530-fold with affinity chromatography using 2’,5′-ADP Sepharose 4B from sheep liver. The effects of reduced glutathione (GSH) and ascorbic acid (vitamin C) on G6PD activity were explored. GSH and ascorbic acid showed a significant inhibitory effect on G6PD, and IC₅₀ values were found as 0.37 µM and 34.66 µM, respectively. The inhibition type from Lineweaver-Burk plots of these compounds was identified as non-competitive inhibition. The <i>K_i</i> values of GSH and ascorbic acid were calculated as 0.48 µM and 30.47 µM, respectively. In this study, it was observed that GSH and ascorbic acid antioxidant compounds exhibit an inhibitory effect on G6PD and may be protective and preventive against cancer.

葡萄糖-6-磷酸脱氢酶（Glucose-6-phosphate dehydrogenase, G6PD）是一类具备多种关键生化功能的酶。然而在多种癌症疾病中，G6PD活性升高会促使癌细胞增殖，因此G6PD抑制剂已成为癌症治疗领域的重要研究方向。本研究通过以2',5'-腺苷二磷酸琼脂糖凝胶4B为配基的亲和层析法，从绵羊肝脏中纯化得到G6PD，纯化倍数达4530倍。随后探究了还原型谷胱甘肽（reduced glutathione, GSH）与抗坏血酸（ascorbic acid, 维生素C）对G6PD活性的影响。实验结果表明，还原型谷胱甘肽与抗坏血酸对G6PD具有显著的抑制作用，二者的半数抑制浓度（IC₅₀）分别为0.37 µM与34.66 µM。通过莱恩韦弗-伯克作图法（Lineweaver-Burk plots）分析，确定这两种化合物的抑制类型为非竞争性抑制（non-competitive inhibition）。二者的抑制常数（K_i）分别计算为0.48 µM与30.47 µM。本研究证实，还原型谷胱甘肽与抗坏血酸这两种抗氧化化合物对G6PD具有抑制活性，有望在癌症防护与预防中发挥作用。