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J Pept Sci. 2017 Dec;23(12):880-888. doi: 10.1002/psc.3052. Epub 2017 Nov 7.

Structural and functional studies of differentially O-glycosylated analogs of a thrombin inhibitory peptide - variegin.

Author information

1
National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
2
Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad, 121001, India.
3
International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.

Abstract

Variegin is a 32-amino acid long thrombin inhibitory peptide isolated from the salivary gland extract of tropical bont tick Amblyomma variegatum. It was identified to be O-glycosylated on its Thr-14 side chain, and this glycosylated form was 14-fold more potent than that of its non-glycosylated form. However, as the identity of this glycosylation remained elusive, the mechanistic details underlying its functional impact are not yet known. In this report, we synthesized four different O-glycosylated analogs of variegin bearing physiologically relevant sugars on its Thr-14. Functional characterization of these analogs by enzyme inhibitory kinetics and surface plasmon resonance methods showed that all the synthesized glycopeptides are strong thrombin inhibitors. Structural studies by macromolecular docking identified that the sugar moiety of these peptides can potentially mediate favorable interactions with amino acids at the base of thrombin's autolysis loop. This report, for the first time, describes the impact of differential glycosylation on the function of a thrombin inhibitory peptide and tries to provide structural insights into the relevance of peptide glycosylation in thrombin inhibition.

KEYWORDS:

enzyme kinetics; glycopeptides; protein-carbohydrate interactions; surface plasmon resonance; thrombin inhibitors

PMID:
29110415
DOI:
10.1002/psc.3052
[Indexed for MEDLINE]

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