Study on the characteristics of IGF?I degradation enzyme in kidney of chicken

Chicken insulin like growth factor Ⅰ(IGF?Ⅰ)labeled by 125 I was incubated with IGF?Ⅰ degradation enzyme(crude extraction from kidney)under various conditions,such as incubation time,temperature,pH,and content of crude enzyme.When the reaction stopped,the mixture was centrifuged,the CPM(counts per minute)of supernatant indicated the activity of IGF?Ⅰ degradation enzyme.The results showed:1)The optimum incubation time of the enzyme was 30 min.2)The suitable content of crude enzyme was below 1 08 μg·μL -1 .3)The enzyme had maximum activity at 45 ℃.4)Below 50 ℃ the activity of enzyme had no change;but if the temperature reached 55 ℃,it dropped suddeny;at 60 ℃ it dropped to about 20% of the highest activity.5)The most appropriate pH for the enzyme was 6 5?7 0.