tailieunhanh - Báo cáo Y học: Processing, stability, and kinetic parameters of C5a peptidase from Streptococcus pyogenes

Arecombinant streptococcalC5apeptidasewas expressed in Escherichia coliand its catalytic properties and thermal sta-bility were subjected to examination. It was shown that the NH2 -terminal region ofC5a peptidase (Asn32–Asp79/ Lys90) forms the pro-sequence segment. Upon maturation the propeptide is hydrolyzed either via an autocatalytic intramolecular cleavage or by exogenous protease strepto-pain. At pH the enzyme exhibited maximum activity in the narrow range oftemperatures between 40 and 43 C | Eur. J. Biochem. 269 4839-4851 2002 FEBS 2002 doi Processing stability and kinetic parameters of C5a peptidase from Streptococcus pyogenes Elizabeth T. Anderson1 Michael G. Wetherell1 Laurie A. Winter1 Stephen B. Olmsted1 Patrick P. Cleary2 and Yury V. Matsuka1 1 Wyeth Research West Henrietta NY USA 2Microbiology Department University of Minnesota Minneapolis MN USA A recombinant streptococcal C5a peptidase was expressed in Escherichia coli and its catalytic properties and thermal stability were subjected to examination. It was shown that the NH2-terminal region of da peptidase Asn32-Asp79 Lys90 forms the pro-sequence segment. Upon maturation the propeptide is hydrolyzed either via an autocatalytic intramolecular cleavage or by exogenous protease strepto-pain. At pH the enzyme exhibited maximum activity in the narrow range of temperatures betwenn 40 nnd 43 C. The process of heat 061 111 1011 of 5 5a 011011 6 investigated by fluorescence and circular dichroism spectroscopy revealed that the protein undergoes biphasic unfolding transition with Tm of 00 rnid 00 C suggesting melting of different parts of the molecule itúh different atability. Unfolding of the less stable structures was accompanied by the loss ofproteolytic activity. Using synthetic peptides corresponding to the COOH-terminus ofhuman complement C5a we demonstrated that in vitro peptidase catalyzes hydrolysis of wwo Hisfi7-Lys68 ndd A1m87-her59 hspdhe bonds. The high catalytic efficiency obtained for the SQLRANISHKDMQLGR extended peptide compared to the poor hydrolysis of iss deri vaiive Ac-SQLR A NISH-pNA that lacks residues at P2 -P7 positions suggest the importance of da ppptids mteraasions tst th the P side of the substrate. Keywords maturation propeptide streptopain denaturation substrate binding. Group A streptococcus Streptococcus pyogenes is a common human pathogen causing a wide variety of diseases. These include relatively mild pathological conditions such .