tailieunhanh - Báo cáo khoa học: Detection of native peptides as potent inhibitors of enzymes Crystal structure of the complex formed between treated bovine a-chymotrypsin and an autocatalytically produced fragment, Ile-Val-Asn-Gly-Glu-Glu-Ala-Val-Pro-Gly-Ser-Trp-Pro-Trp, at 2.2 A˚ resolution

Chymotrypsin is a prominent member of the family of serine proteases. The present studies demonstrate the presence of a native fragment contain-ing 14 residues from Ile16 to Trp29 in a-chymotrypsin that binds to chy-motrypsin at the active site with an exceptionally high affinity of ± ·10 )11 mand thus works as a highly potent competitive inhib-itor. The commercially available a-chymotrypsin was processed through a three phase partitioning system (TPP). The treated enzyme showed consid-erably enhanced activity. . | iFEBS Journal Detection of native peptides as potent inhibitors of enzymes Crystal structure of the complex formed between treated bovine a-chymotrypsin and an autocatalytically produced fragment Ile-Val-Asn-Gly-Glu-Glu-Ala-Val-Pro-Gly-Ser-Trp-Pro-Trp at A resolution Nagendra Singh1 Talat Jabeen1 Sujata Sharma1 Ipsita Roy2 Munishwar N. Gupta2 Sameeta Bilgrami1 Rishi K. Somvanshi1 Sharmistha Dey1 Marcus Perbandt3 Christian Betzel3 A. Srinivasan1 and Tej P. Singh1 1 Department of Biophysics All India Institute of MedicalSciences New Delhi India 2 Department of Chemistry Indian Institute of Technology Delhi New Delhi India 3 Institute of MedicalBiochemistry and Molecular Biology University of Hamburg c o DESY Hamburg Germany Keywords autodigestion complex crystal structure inhibition peptide inhibitor Correspondence T. P. Singh Department of Biophysics All India Institute of MedicalSciences Ansari Nagar New Delhi 110 029 India Fax 91 11 2658 8663 Tel 91 11 2658 8931 E-mail tps@ Received 2 August 2004 revised 4 November 2004 accepted 22 November 2004 doi Chymotrypsin is a prominent member of the family of serine proteases. The present studies demonstrate the presence of a native fragment containing 14 residues from Ile16 to Trp29 in a-chymotrypsin that binds to chymotrypsin at the active site with an exceptionally high affinity of X 10-11 M and thus works as a highly potent competitive inhibitor. The commercially available a-chymotrypsin was processed through a three phase partitioning system TPP . The treated enzyme showed considerably enhanced activity. The 14 residue fragment was produced by autodigestion of a TPP-treated a-chymotrypsin during a long crystallization process that lasted more than four months. The treated enzyme was purified and kept for crystallization using vapour the diffusion method at 295 K. Twenty milligrams of lyophilized protein were dissolved in 1 mL of 25 mM sodium acetate buffer