Torsoni M A, Viana R I, Ogo S H
Departamento de Bioquímica, IB, Universidade Estadual de Campinas, SP, Brasil.
Biochem Mol Biol Int. 1998 Sep;46(1):147-56. doi: 10.1080/15216549800203652.
Thiol groups of hemoglobin and blood glutathione are higher in Geochelone carbonaria than in Geochelone denticulata. Exposure of stripped hemolysate of both tortoises to terc-butyl hydroperoxide, resulted in a higher ferroheme oxidation of G. denticulata hemoglobin. In this example glutathione reductase and glutathione peroxidase, were not active due to the absence of GSH and NADPH, suggesting that the thiol groups of G. carbonaria hemoglobin act as antioxidant, similar to GSH. In the total hemolysate, however, where the antioxidant enzymes are active, both species showed similar levels of hemoglobin oxidation, suggesting that the protective effect of thiol groups of hemoglobin are less effective for heme protection. The activity of glutathione reductase and glutathione peroxidase was higher in erythrocytes of G. denticulata and the activity of catalase and superoxide dismutase was higher in erythrocytes of G. carbonaria.
红腿陆龟血红蛋白和血液中谷胱甘肽的硫醇基团含量高于栉龟。将两种龟的脱铁血红蛋白溶液暴露于叔丁基过氧化氢中，栉龟血红蛋白的高铁血红素氧化程度更高。在这个例子中，由于缺乏谷胱甘肽（GSH）和烟酰胺腺嘌呤二核苷酸磷酸（NADPH），谷胱甘肽还原酶和谷胱甘肽过氧化物酶没有活性，这表明红腿陆龟血红蛋白的硫醇基团起到了类似谷胱甘肽的抗氧化作用。然而，在抗氧化酶具有活性的全血溶血产物中，两种龟的血红蛋白氧化水平相似，这表明血红蛋白硫醇基团对血红素的保护作用效果较差。栉龟红细胞中谷胱甘肽还原酶和谷胱甘肽过氧化物酶的活性较高，而红腿陆龟红细胞中过氧化氢酶和超氧化物歧化酶的活性较高。
