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Volume 204, Issue 1 p. 147-153
Free Access

Isolation and structural determination of three peptides from the insect Locusta migratoria

Identification of a deoxyhexose-linked peptide

Norihiko NAKAKURA

Norihiko NAKAKURA

Laboratoire de Chimie Organique des Substances Naturelles, URA CNRS 31, Strasbourg, France

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Hélène HIETTER

Hélène HIETTER

Laboratoire de Chimie Organique des Substances Naturelles, URA CNRS 31, Strasbourg, France

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Alain VAN DORSSELAER

Alain VAN DORSSELAER

Laboratoire de Chimie Organique des Substances Naturelles, URA CNRS 31, Strasbourg, France

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Bang LUU

Corresponding Author

Bang LUU

Laboratoire de Chimie Organique des Substances Naturelles, URA CNRS 31, Strasbourg, France

Correspondence to B. Luu, Laboratoire de Chimie Organique des Substances Naturelles, URA CNRS 31, 5, rue Blaise Pascal, F-67084 Strasbourg, FranceSearch for more papers by this author
First published: February 1992
Citations: 75

Note. The novel amino acid sequence data published here have been submitted to the EMBL sequence data bank and are available under the accession numbers P80058 (PMPC), P80059 (PMPD1) and P80060 (PMPD2).

Abstract

We have isolated three novel peptides from the aqueous extract of the pars intercerebralis of male and female adults of the insect Locusta migratoria. After extensive HPLC purification, the peptides were characterised by automated Edman degradation and electrospray mass spectrometry: one is a 35-residue peptide (3752.3 ± 1.1 Da) containing six cysteines involved in three intramolecular disulfide bridges, the second is a 36-residue peptide (3919.2 ± 0.9 Da), also cross-linked by three intramolecular disulfide bridges. This second peptide is post-translationally modified by a single fucose moiety, which was identified by gas chromatography coupled to mass spectrometry. These two peptides show a strong sequence similarity. Additionally, they were also found in larger amounts in the fat body of Locusta; this finding raises the question of their exact site of synthesis. The third peptide (5776.3 ± 0.9 Da), a 54-residue peptide cross-linked by six intramolecular disulfide bridges, is structurally related to the two other peptides, but to a lesser extent. Mass spectrometry has shown that all the cysteines within these three peptides are involved in intramolecular disulfide bridges; however, the location of these bridges is not yet established and is currently being investigated. A computer search of sequence data banks did not reveal any significant similarity of these three peptides with other known proteins.

Abbreviations

  • [M + H]+
  • protonated molecular ion
  • [M +nH]n+
  • multiply charged ion. Pth, phenylthiohydantoin
  • Enzymes

  •  
  • Trypsin (EC 3.4.21.4)