酶的化学修饰
参考答案：
酶蛋白肽链上某些残基在酶的催化下发生可逆的共价修饰，从而导致酶活性改变。
In the 1930s, the two countries were at ______ war, and his father was fighting at _____ front.
A．the; 不填
B．不填; the
C．the; the
D．不填;不填
票汇业务和托收业务都是商业信用，使用的都是商业汇票。( )
