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Conformational analysis of the type II and type III collagen α‐1 chain N‐telopeptides by 1 H‐NMR spectroscopy and restrained molecular mechanics calculations
Author(s) -
Otter Albin,
Scott Paul G.,
Kotovych George
Publication year - 1993
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360330914
Subject(s) - chemistry , nuclear magnetic resonance spectroscopy , spectroscopy , crystallography , vicinal , dihedral angle , amide , stereochemistry , two dimensional nuclear magnetic resonance spectroscopy , hydrogen bond , proton nmr , molecule , j coupling , side chain , organic chemistry , physics , quantum mechanics , polymer
The type II and type III collagen α‐1 chain N‐telopeptides are a nonadecamer with the sequence pEMAGGFDEKAGGAQLGVMQ‐NH 2 and a tetradecamer with the sequence pEYEAYDVKSGVAGG‐NH 2 , respectively. Their conformations have been studied in CD 3 OH/H 2 O (60/40) solution by means of two‐dimensional proton nmr spectroscopy. Based on double quantum filtered correlation spectroscopy, total correlation spectroscopy, rotating frame nuclear Overhauser enhancement (ROE) spectroscopy, and nuclear Over‐hauser enhancement (NOE) spectroscopy experiments, all resonances were assigned and the conformational properties were analyzed in terms of vicinal NH‐H α coupling constants, sequential and medium‐range NOEs (ROEs), and amide proton temperature coefficients. The NOE distance constraints as well as dihedral constraints based on the vicinal NH‐H α coupling constants were used as input parameters for restrained molecular mechanics, consisting of restrained molecular dynamics and restrained energy minimization calculations. The type II N‐telopeptide's conformation is dominated by a fused βγ‐turn between Phe 6 and Ala 10 , stabilized by three hydrogen bonds and a salt bridge between the side‐chain end groups of Glu 8 and Lys 9 . The first 5 amino acids are extended with a much higher degree of conformational freedom. The 2 Gly residues following the turns were found to be highly flexible (hinge‐like), leaving the spatial position of the second half of the molecule relative to the fused βγ‐turn undefined. In the type III telopeptide, a series of sequential NH( i )‐NH( i + 1) ROEs were observed between the amino acids Tyr 2 and Ser 9 , indicating that a fraction of the conformational space is helical. However, the absence of medium‐range ROEs and the lack of regularity of the effects associated with α‐helices suggest the presence of a nascent rather than a complete helix. © 1993 John Wiley & Sons, Inc.