Infrared spectra and structure of synthetic polytripeptides

Abstract

SynopsisA number of polytripeptides related to collagen, namely, (Gly-Pro-Pro),, (Gly-Pro-Hyp),, (Gly-Hyp-Hyp),, (Gly-Pro-Ala),, (Gly-Pro-Leu),, (Gly-Pro-Gly),, (Gly-Ala-Pro),, (GlyAla-Hyp),, (Ala-Pro-Pro),, and (Ala-Hyp-Hyp), were investigated by the methods of ir spectroscopy and hydrogen-deuterium kinetics. Strength and order of interpeptide hydrogen bonds of the polytripeptides in a triple-helical conformation were found to depend on the amino acid composition and residue sequence in the triplets. Correlation of x-ray diffraction and spectroscopic data for (Gly-Pro-Hyp), showed that the increase of the helix parameter in the process of dehydration is accompanied with the weakening of interpeptide hydrogen bonds. Influence of bound water on the length and order of interchain hydrogen bonding was also examined. It was shown that the incorporation of water molecules into the triple helix depends on the amino acid composition and residue sequence. Synthetic models and native collagens were compared.

A novel structural model for collagen: Water—carbonyl helix

“…The amide A frequency for these structures is about 40-60 cm -~ higher thanthat for a-helices,/3-structures and random coils. It is suggested that a high-frequency shift might be due to the existence of weak hydrogen bonds [21,22,24]. As mentioned above, such hydrogen bonds in the watercarbonyl structure are the hydrogen bonds formed by glycine NH-groups and water molecules.…”

Perspectives on the synthesis and application of triple-helical, collagen-model peptides

“…A large increase in amide A frequency occurs for triple-helix formation, as evidenced by a change in amide A frequency of 3323 cm-' for Z-( Gly-Pro-Pro),-OCH3 to 3359 cm-' for Z-( GlyPro-Pro),-OCH3 . 48 This high-frequency shift may be due to long hydrogen bonds, and the higher value stays relatively constant for n = 4-8.…”

Infrared Assessment of Bone Quality: A Review

“…As in the case of mineral analysis, information on protein structure is extracted from broad spectral bands consisting of component peaks resulting from the Amide I modes of various secondary structures by using a spectral resolution technique such as Fourier self-deconvolution, second-derivative spectroscopy, and difference FTIR spectroscopy [15,25,[36][37][38][39]76]. The major underlying bands and their assignments are summarized (Table 1).…”