【摘要】 通过对牦牛肌红蛋白的含量和cDNA序列的测定及心肌肌红蛋白氧化和脂类氧化相关性的研究,初步探讨了牦牛适应高原低氧环境的机理.牦牛与黄牛的肌红蛋白cDNA序列比较,二者只有2个碱基的差异(89位氨基酸由cac变为cat,91位氨基酸由gcc变为gct),但由于氨基酸密码子简并性,两者的氨基酸序列没有差异.牦牛的骨骼肌的肌红蛋白含量为488.3 nmol/g,与黄牛相比没有显著差异,但牦牛心肌的肌红蛋白含量为823.4 nmol/g,比黄牛高61.2%(P<0.05).在4℃贮存下,牦牛心肌中肌红蛋白的氧化速率与黄牛相比没有显著差异,而牦牛骨骼肌中肌红蛋白的氧化速率比黄牛慢25.8%(P<0.05).牦牛骨骼肌中脂类氧化的硫代巴比妥酸反应物质(TBARS)值比黄牛低63.5%(P<0.05).结果表明,牦牛适应高原的低氧环境,不是通过改变其肌红蛋白氨基酸序列从而引起蛋白质结构的变化来实现的,提高肌红蛋白在体内的含量以及减缓肌红蛋白和脂类的氧化速率则可能是牦牛对高原低氧适应的原因之一.更多还原

【Abstract】 The cDNA sequence of yak myoglobin(Mb),as well as Mb concentration and oxidation related to lipid oxidation in yak skeletal and cardiac muscle,were investigated in order to understand the mechanism of yak’s adaptation to hypoxia environment.Comparison of Mb cDNA sequence in yak and bovine revealed that there were only two different bases(cac→cat and gcc→gct,at the 89th and 91th amino acids) but the amino acids sequence had no difference due to the degeneracy of codons.The concentration of yak Mb in skeletal muscles was 488.3 nmol/g and had no significant difference with that of bovine skeletal muscles,however,the concentration of yak Mb in cardiac muscles was 823.4 nmol/g,being 61.2%(P<0.05) higher than that in bovine cardiac muscles.During storage at 4℃,the oxidation rate of yak Mb in skeletal muscles showed no significant difference with that of bovine skeletal muscles,however,the oxidation rate of yak Mb in cardiac muscles was slower by 25.8%(P<0.05)than that of bovine.The thiobarbituric acidreactive substance(TBARS) value in yak skeletal muscles was slower by 63.5%(P<0.05)than that of bovine.Our study demonstrated that yak’s adaptation to hypoxia environment was not due to the change of the amino acid sequence thus protein structure of yak’s myoglobin through evolution,but by the increase of its Mb concentration and the slower Mb and lipid oxidation rate.更多还原