Aft R L, Mueller G C
J Biol Chem. 1984 Jan 10;259(1):301-5.
Hemin, in the presence of 2-mercaptoethanol and oxygen, catalyzes the selective degradation of heme-binding proteins to small peptide fragments. Among the proteins examined, the heme-binding protein of rabbit serum (HBP-93) proved to be unusually sensitive. Myoglobin also exhibited considerable sensitivity whereas hemopexin and bovine serum albumin were only slightly susceptible to this degradative action of hemin. The reaction with HBP-93 depended upon coordination of the protein with hemin, was optimal at pH 6.5 and increased 4-fold as the temperature was elevated from 10 to 60 degrees C. The requirement for both oxygen and the reducing agent, 2-mercaptoethanol, and the partial protection of HBP-93 to degradation by catalase, superoxide dismutase, mannitol, and thiourea suggest the involvement of reduced oxygen species in the reaction. A possible role for the heme-mediated degradation of proteins in cell differentiation and other biological responses is discussed.
在2-巯基乙醇和氧气存在的情况下，氯高铁血红素催化血红素结合蛋白选择性降解为小肽片段。在所检测的蛋白质中，兔血清的血红素结合蛋白（HBP-93）被证明异常敏感。肌红蛋白也表现出相当的敏感性，而血红素结合蛋白和牛血清白蛋白对氯高铁血红素的这种降解作用仅稍有敏感。与HBP-93的反应取决于蛋白质与氯高铁血红素的配位，在pH 6.5时最佳，并且当温度从10℃升高到60℃时增加4倍。对氧气和还原剂2-巯基乙醇的需求，以及过氧化氢酶、超氧化物歧化酶、甘露醇和硫脲对HBP-93降解的部分保护作用表明反应中涉及还原态氧物种。本文讨论了血红素介导的蛋白质降解在细胞分化和其他生物学反应中的可能作用。
