无色杆菌蛋白酶Ⅰ肽链N端作用的突变研究

The Mutation Studies on the N-Terminal Action of Achromobacter Protease Ⅰ Peptide Chain

无色杆菌蛋白酶Ⅰ（AchromobacterproteaseⅠ，APⅠ）是高度专一于赖氨酸的丝氨酸蛋白酶．比较其它典型同类蛋白酶的一级结构，该酶的成熟体肽键在N端和C端分别长出9个和26个氨基酸践基．在其N端设计和构建了一些突变体，它们分别具有缩短或延长的N端．这些突变体低于天然酶的活性和稳定性的结果揭示，N端这部分延长在稳定该酶的活性构象方面起着重要作用．

Achromobacter Protease Ⅰ (APⅠ)is a mammalian-type serine protease, synthesized byAchromobacter lyticus M497-1. It hydrolyzes specifically the lysyl peptide bond including the lysylproline bond. APⅠ can be used as an effective tool for peptide fragmentation in protein sequenceanalysis. In comparison with the primary structures of APⅠ and other related serine proteases,there are 9 and 26 amino acid residue extensions respectively at N and C-terrnini of mature APⅠ.Some mutations with the extended and shortened N-termini were designed and constructed. Theirlower activities and stabilities than those of natural APⅠ suggested that the N-terminus with 9amino acid residues plays an important role in stabilizing the active con formation of APⅠ.