Expression,Purification and Crystal Structure of a Truncated Acylpeptide Hydrolase from Aeropyrum pernix K1

【摘要】：正 Acylpeptide hydrolase (APH) catalyzes the N-terminal hydrolysis of N~α-acylpeptides to releaseN~α-acylated amino acids. The crystal structure of recombinant APH from the thermophilic archaeon Aeropyrumpernix K1 (apAPH) was reported recently to be at a resolution of 2.1 (?) using X-ray diffraction.A truncatedmutant of apAPH that lacks the first short α-helix at the N-terminal,apAPH-△(1-21),was cloned,expressed,characterized and crystallized.Data from biochemical experiments indicate that the optimum temperature ofapAPH is decreased by 15℃ with the deletion of the N-terminal α-helix.However,the enzyme activity at theoptimal temperature does not change.It suggests that this N-terminal α-helix is essential for thermostability.Here,the crystal structure of apAPH-△(1-21) has been determined by molecular replacement to 2.5 (?). Acomparison between the two structures suggests a difference in thermostability,and it can be concluded thatby adding or deleting a linking structure (located over different domains),the stability or even the activity ofan enzyme can be modified.