The protease from ?Serratia marcescens ?41003(2)was completely inactivated by EDTA at pH7?0 and was reactivated by Ca??2+?,thus,Ca??2+? is essential for the activity of the enzyme.

• 终浓度为5mmol/L的EDTA可彻底抑制粘质赛氏菌41003（2）胞外蛋白酶活力，而Ca2＋可以回复部分酶活力，表明Ca2＋为酶活力所必需；