Sequential 1H‐NMR assignments and secondary structure of the sea anemone polypeptide anthopleurin‐A

Bridget C. MABBUTT, Raymond S. NORTON

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Abstract

The sequence‐specific assignment of resonances in the 500‐MHz 1H‐NMR spectrum of a cardioactive sea anemone polypeptide, anthopleurin‐A, is described. The assignment procedure involved analysis of two‐dimensional phase‐sensitive multiple‐quantum‐filtered, double‐quantum, homonuclear Hartmann‐Hahn and nuclear Overhauser effect spectra. Using sequential information, specific assignments have been made for resonances arising from all 49 amino acid residues. Resonances arising from a number of residues in a minor conformer present in solution are also assigned. These results greatly extend previous resonance assignments made from spectra acquired at 300 MHz [Gooley, P. R. and Norton, R. S. (1985) Eur. J. Biochem. 153, 529–539] and provide the basis for a more accurate definition of the conformation of anthopleurin‐A in aqueous solution. The secondary structure includes a four‐stranded antiparallel β‐sheet encompassing residues 2–4, 21–23, 34–36 and 45–49, and possibly a β‐bulge located at Ser‐19 and Gly‐20. A type II β‐turn is formed by residues 30–33. These structural elements also occur within other related sea anemone polypeptides, but the conformation of the small loop region containing Pro‐41 appears to be unique to anthopleurin‐A.

Original languageEnglish
Pages (from-to)555-563
Number of pages9
JournalEuropean Journal of Biochemistry
Volume187
Issue number3
DOIs
Publication statusPublished - 1990
Externally publishedYes

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