( 4 ) in artificial pepsin digestive system with ph2 . 0 , due to the acid denaturation , the pigg was hydrolyzed wholly , in the system with ph3 . 0 and 4 . 0 , although not all entirely pigg could be detected , but the pigg antibody activities against e . coli still existed without changing , this indicates that the f ( ab " ) 2 with antigen - binding activity still remain complete during digesting process ( 4 )在ph2 . 0的人工胃液消化體系中,由于酸變性pigg全部水解;在ph3 . 0和ph4 . 0的人工胃液消化體系中,盡管檢測不到所有的pigg ,但pigg仍可與e . coli特異性結(jié)合且凝集價未發(fā)生變化,表明在消化過程中具有抗原結(jié)合活性的f ( ab ) _ 2片段仍可完整地保留下來。