This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
4wxv
From Proteopedia
Human cationic trypsin K97D mutant in complex with bovine pancreatic trypsin inhibitor (BPTI)
Structural highlights
Disease[TRY1_HUMAN] Defects in PRSS1 are a cause of pancreatitis (PCTT) [MIM:167800]. A disease characterized by the presence of calculi in pancreatic ducts. It causes severe abdominal pain attacks.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Function[TRY1_HUMAN] Has activity against the synthetic substrates Boc-Phe-Ser-Arg-Mec, Boc-Leu-Thr-Arg-Mec, Boc-Gln-Ala-Arg-Mec and Boc-Val-Pro-Arg-Mec. The single-chain form is more active than the two-chain form against all of these substrates.[12] [BPT1_BOVIN] Inhibits trypsin, kallikrein, chymotrypsin, and plasmin. Publication Abstract from PubMedHuman mesotrypsin is highly homologous to other mammalian trypsins, and yet is functionally unique in possessing resistance to inhibition by canonical serine protease inhibitors and in cleaving these inhibitors as preferred substrates. Arg-193 and Ser-39 have been identified as contributors to the inhibitor resistance and cleavage capability of mesotrypsin, but it is not known whether these residues fully account for the unusual properties of mesotrypsin. Here we use human cationic trypsin as a template for engineering a gain of catalytic function, assessing mutants containing mesotrypsin-like mutations for resistance to inhibition by bovine pancreatic trypsin inhibitor (BPTI) and amyloid precursor protein Kunitz protease inhibitor (APPI), and for the ability to hydrolyze these inhibitors as substrates. We find that Arg-193 and Ser-39 are sufficient to confer mesotrypsin-like resistance to inhibition; however, compared with mesotrypsin, the trypsin-Y39S/G193R double mutant remains 10-fold slower at hydrolyzing BPTI and 2.5-fold slower at hydrolyzing APPI. We identify two additional residues in mesotrypsin, Lys-74 and Asp-97, which in concert with Arg-193 and Ser-39 confer the full catalytic capability of mesotrypsin for proteolysis of BPTI and APPI. Novel crystal structures of trypsin mutants in complex with BPTI suggest that these four residues function cooperatively to favor conformational dynamics that assist in dissociation of cleaved inhibitors. Our results reveal that efficient inhibitor cleavage is a complex capability to which at least four spatially separated residues of mesotrypsin contribute. These findings suggest that inhibitor cleavage represents a functional adaptation of mesotrypsin that may have evolved in response to positive selection pressure. Mesotrypsin Has Evolved Four Unique Residues to Cleave Trypsin Inhibitors as Substrates.,Alloy AP, Kayode O, Wang R, Hockla A, Soares AS, Radisky ES J Biol Chem. 2015 Jul 14. pii: jbc.M115.662429. PMID:26175157[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||||||
