题目

由m个氨基酸构成的一个蛋白质分子，含n条环状肽链，其共有z条肽链。该蛋白质分子中含有的肽键数为  A.m－z＋n           B.m－n－z          C.m－n＋z              D.m＋z＋n 答案：A420, 309 should be read .A. four hundred and twenty thousands three hundred and nineB. four hundred and twenty thousand and three hundred and nineC. four hundred and twenty thousands and three hundred and nineD. four hundred and twenty thousand three hundred and nine