Two-dimensional sup 1 H nuclear magnetic resonance study of AaH IT, an anti-insect toxin from the scorpion Androctonus australis Hector. Sequential resonance assignments and folding of the polypeptide chain

Journal Article · Tue Feb 19 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00221a016· OSTI ID:5510293

Darbon, H ^[1]; Weber, C; Braun, W ^[2]

---

1. Laboratoire de Biochimie, Marseille (France)
2. Institut fur Molekularbiologie und Biophysik, Zuerich (Switzerland)

Sequence-specific nuclear magnetic resonance assignments for the polypeptide backbone and for most of the amino acid side-chain protons, as well as the general folding of AaH IT, are described. AaH IT is a neurotoxin purified from the venom of the scorpion Androctonus australis Hector and is specifically active on the insect nervous system. The secondary structure and the hydrogen-bonding patterns in the regular secondary structure elements are deduced from nuclear Overhauser effects and the sequence locations of the slowly exchanging amide protons. The backbone folding is determined by distance geometry calculations with the DISMAN program. The regular secondary structure includes two and a half turns of {alpha}-helix running from residues 21 to 30 and a three-stranded antiparallel {beta}-sheet including peptides 3-5, 34-38, and 41-46. Two tight turns are present, one connecting the end of the {alpha}-helix to an external strand of the {beta}-sheet, i.e., turn 31-34, and another connecting this same strand to the central one, i.e., turn 38-41. The differences in the specificity of these related proteins, which are able to discriminate between mammalian and insect voltage-dependent sodium channels of excitable tissues, are most probably brought about by the position of the C-terminal peptide with regard to a hydrophobic surface common to all scorpion toxins examined thus far. Thus, the interaction of a given scorpion toxin with its receptor might well be governed by the presence of this solvent-exposed hydrophobic surface, whereas adjacent areas modulate the specificity of the interaction.

• OSTI ID: 5510293
• Journal Information: Biochemistry; (United States), Vol. 30:7; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
POLYPEPTIDES
AMINO ACID SEQUENCE
TOXINS
NUCLEAR MAGNETIC RESONANCE
CHEMICAL SHIFT
MOLECULAR STRUCTURE
PROTONS
RECEPTORS
SCORPIONS
ANIMALS
ANTIGENS
ARACHNIDS
ARTHROPODS
BARYONS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INVERTEBRATES
MAGNETIC RESONANCE
MATERIALS
MEMBRANE PROTEINS
NUCLEONS
ORGANIC COMPOUNDS
PEPTIDES
PROTEINS
RESONANCE
TOXIC MATERIALS
550201* - Biochemistry- Tracer Techniques