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NMR structure determination of tick anticoagulant peptide (TAP)
Author(s) -
LimWilby Marguerita S.L.,
Vlasuk George P.,
Brunck Terence K.,
Hallenga Klaas,
Maeyer Marc De,
Lasters Ignace
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560040205
Subject(s) - heteronuclear molecule , heteronuclear single quantum coherence spectroscopy , chemistry , two dimensional nuclear magnetic resonance spectroscopy , nuclear magnetic resonance spectroscopy , nuclear overhauser effect , serine protease , stereochemistry , crystallography , protease , biochemistry , enzyme
Tick anticoagulant peptide (TAP) is a potent and selective 60‐amino acid inhibitor of the serine protease Factor Xa (fXa), the penultimate enzyme in the blood coagulation cascade. The structural features of TAP responsible for its remarkable specificity for fXa are unknown, but the binding to its target appears to be unique. The elucidation of the TAP structure may facilitate our understanding of this new mode of serine protease inhibition and could provide a basis for the design of novel fXa inhibitors. Analyses of homo‐ and heteronuclear two‐dimensional NMR spectra (total correlation spectroscopy, nuclear Overhauser effect spectroscopy [NOESY], constant time heteronuclear single quantum correlation spectroscopy [CT‐HSQC], and HSQC‐NOESY; 600 MHz; 1.5 mM TAP; pH 2.5) of unlabeled, 13 C‐labeled, and 15 N‐labeled TAP provided nearly complete 1 H sequence‐specific resonance assignments. Secondary structural elements were identified by characteristic NOE patterns and D 2 O amide proton‐exchange experiments. A three‐dimensional structure of TAP was generated from 412 NOESY‐derived distance and 47 dihedral angle constraints. The structural elements of TAP are similar in some respects to those of the Kunitz serine protease inhibitor family, with which TAP shares weak sequence homology. This structure, coupled with previous kinetic and biochemical information, confirms previous suggestions that TAP has a unique mode of binding to fXa.