Proton NMR assignments and secondary structure of the snake venom protein echistatin

• Published in: Biochemistry (Easton) Vol. 30; no. 50; pp. 11625 - 11636
• Main Authors: Chen, Yuan, Pitzenberger, Steven M, Garsky, Victor M, Lumma, Patricia K, Sanyal, Gautam, Baum, Jean
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 17.12.1991
• Subjects: 550201 - Biochemistry- Tracer Techniques; Amino Acid Sequence; AMINO ACIDS; Analytical, structural and metabolic biochemistry; ANIMALS; ARGININE; ASPARTIC ACID; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BLOOD COAGULATION; BLOOD PLATELETS; BODY FLUIDS; CARBOXYLIC ACIDS; Circular Dichroism; Fundamental and applied biological sciences. Psychology; GLYCINE; Hydrogen-Ion Concentration; INHIBITION; MAGNETIC RESONANCE; Magnetic Resonance Spectroscopy; MATERIALS; Miscellaneous; Molecular Sequence Data; NUCLEAR MAGNETIC RESONANCE; ORGANIC ACIDS; ORGANIC COMPOUNDS; OVERHAUSER EFFECT; Peptides; Protein Conformation; Proteins; Protons; REPTILES; RESONANCE; SNAKES; Spectrophotometry, Ultraviolet; venom; VENOMS; VERTEBRATES; Viper Venoms - chemistry; Proteins; Vertebrata; Circular dichroism spectrometry; Venom; Reptilia; NMR spectrometry; Echis carinatus; Secondary structure; Ophidia; Two dimension spectrometry; Pulse sequence
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00114a004

The snake venom protein echistatin is a potent inhibitor of platelet aggregation. The inhibitory properties of echistatin have been attributed to the Arg-Gly-Asp sequence at residues 24-26. In this paper, sequence-specific nuclear magnetic resonance assignments are presented for the proton resonances of echistatin in water. The single-chain protein contains 49 amino acids and 4 cystine bridges. All of the backbone amide, C alpha H, and side-chain resonances, except for the eta-NH of the arginines, have been assigned. The secondary structure of the protein was characterized from the pattern of nuclear Overhauser enhancements, from the identification of slowly exchanging amide protons, from 3JC alpha H-NH coupling constants, and from circular dichroism studies. The data suggest that the secondary structure consists of a type I beta-turn, a short beta-hairpin, and a short, irregular, antiparallel beta-sheet and that the Arg-Gly-Asp sequence is in a flexible loop connecting two strands of the distorted antiparallel beta-sheet.