POMPILID WASP-DERIVED NEUROPEPTIDES

Abstract: The present invention provides a peptide represented by the amino acid sequence formula (A): H-X1-X2-X3-X4-Gly-X6-X7-Asp-Gln-R wherein: each of X1 and X3 independently represents Arg or Lys, each of X2, X4 and X6 independently represents Ile or Leu, and X7 represents Phe, Tyr or Trp; and R represents -NH2, -Leu-NH2, -Leu-Ser-NH2, -Leu-Ser-Lys-NH2, -Leu-Ser-Arg-NH2, Leu-Ser-Lys-Leu-NH2, or -Leu-Ser-Arg-Leu-NH2; and a salt thereof. In the above, Gly stands for a glycine residue, Asp stands for an aspartic acid residue, Gln stands for a glutamine residue, Arg stands for an arginine residue, Lys stands for a lysine residue, Ile stands for an isoleucine residue, Leu stands for a leucine residue, Phe stands for a phenylalamine residue, Tyr stands for a tyrosine residue, Trp stands for a tryptophan residue, and Ser stands for a serine residue. The peptide acts on glutamate receptors and is expected to be useful in the treatment of cerebral nerve diseases associated with glutamic acid.

Description: DESCRIPTION POMPILID WASP-DERIVED NEUROPEPTIDES TECHNICAL FIELD The present invention relates to novel neuropeptides and more specifically to peptides obtained from the venoms of the solitary wasps Anoplius samariensis and Batozonellus maculifrons, and analogous peptides thereof. BACKGROUND ART Since solitary wasp species such as thread-waisted wasps and pompilid wasps paralyze other insects with their venom, it is believed that the venom contain substances that act on the nervous system. In fact, peptides called mastoparans have been isolated from a certain kind of solitary wasp, and these peptides are used as useful compounds for the study of information transmission system of the living body. On the other hand, various compounds have been isolated in the studies on spider toxins, and it has been confirmed that their effect of paralyzing nerves is based on their inhibitory action on glutamate receptors. Glutamic acid is known to play an important role as an excitatory neurotransmitter mediated by glutamate receptors in the central nervous system (e.g. brain, spinal cord) of mammals, and the synapses of insects and crustaceans. And further, it is known that excess glutamic acid causes over-excitation of nerve cells resulting in death of the nerve cells. Therefore, enhancement of the function of glutamate receptors and conversely temporary blocking of their function are believed to provide therapeutic benefits on cerebral nerve diseases associated with glutamic acid. DISCLOSURE OF THE INVENTION Accordingly, the object of the present invention is to find, in the venom of the solitary wasps, substances that act on the glutamate receptor or substances that promote or inhibit the release of glutamic acid, and to apply them to medical therapeutic purposes. In order to achieve the above object, the present inventors have isolated a peptide (1) represented by SEQ ID NO: 1: H-Arg-Ile-Lys-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (1) and a peptide (97) represented by SEQ ID NO: 2: H-Arg-Ile-Lys-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Arg-Leu-NH2 (97) from the venom sac extracts of solitary wasps A. samariensis and B. maculifrons, on the basis of the ability to enhance or block the neurotransmission through the neuron synapses of lobster's walking leg. Furthermore, peptides related to the above peptides (1) and (97) were synthesized by the conventional solid phase method and their structure-activity relationship was examined. As a result, it was found that the peptides represented by the amino acid sequence formula (A): H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-R (A) wherein: R is basically NH2 f which also may be -Leu-NH2, -Leu-Ser- NH2, -Leu-Ser-Lys-NH2, -Leu-Ser-Arg-NH2, -Leu-Ser-Lys-Leu-NH2, or -Leu-Ser-Arg-Leu-NH2; X- and X3 are basic amino acid residues; X2, X4 and X6 are aliphatic amino acid residues; and X7 is an aromatic amino acid residue, can show the above-mentioned activity. The basic amino acid residues X^ and X3 include arginine or lysine residue, the aliphatic amino acid residues X2, X4 and Q include leucine or isoleucine residue, and the aromatic amino acid residue X7 includes phenylalanine, tyrosine, or tryptophan residue . Accordingly, the present invention provides, as a neuro- peptide, a peptide represented by the amino acid sequence formula (A): H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-R (A) wherein: each of Xi and X3 independently represents Arg or Lys, each of X2, X4 and Xg independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and R represents -NH2, -Leu-NH2, -Leu-Ser-NH2» -Leu-Ser-Lys-NH2, -Leu-Ser-Arg-NH2, -Leu-Ser-Lys-Leu-NH2, or -Leu-Ser-Arg-Leu-NH2; and a salt thereof. As an embodiment, the present invention provides a peptide represented by the amino acid sequence formula (B): U-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-NH 2 (B) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xg independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. As another embodiment, the present invention provides a peptide represented by the amino acid sequence formula (C) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X7-Asp-Gln-Leu-NH 2 (C) wherein : each of Xi and X3 independently represents Arg or Lys, each of X2, X4 and Xs independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. As a further embodiment, the present invention provides a peptide represented by the amino acid sequence formula (D): H-X 1 -X 2 -X3-X4-Gly-X 6 -X7-Asp-Gln-Leu-Ser-NH 2 (D) wherein : each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and X5 independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. As still another embodiment, the present invention provides a peptide represented by the amino acid sequence formula (E): H-X -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-Ser-Lys-NH 2 (E) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and X5 independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. As still another embodiment, the present invention provides a peptide represented by the amino acid sequence formula (F) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-Ser-Arg-NH 2 (F) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xg independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. As still another embodiment, the present invention provides a peptide represented by the amino acid sequence formula (G): H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-Ser-Lys-Leu-NH 2 (G) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xg independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. As still a further embodiment, the present invention provides a peptide represented by the amino acid sequence formula (H) : H-X 1 -X2-X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-Ser-Arg-Leu-NH 2 (H) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and X independently represents lie or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. Among the above peptides provided by the present invention, the most preferred embodiment is a peptide represented by the amino acid sequence formula ( 1) : H-Arg-Ile-Lys-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (1) and a salt thereof, or a peptide represented by the amino acid sequence formula (97): H-Arg-Ile-Lys-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Arg-Leu-NH2 (97) and a salt thereof. As another embodiment, the present invention provides a pharmaceutical composition containing the peptide represented by the amino acid sequence formula (A) or a salt thereof for treatment of glutamate receptor related diseases. As still another embodiment, the present invention provides use of the peptide represented by the amino acid sequence formula (A) or a salt thereof for treatment of glutamate receptor related diseases . As still a further embodiment, the present invention provides a method for treatment of glutamate receptor related diseases which composing administering an effective amount of the peptide represented by the amino acid sequence formula (A) or a salt thereof. BEST MODE FOR CARRYING OUT THE INVENTION In the present specification and in each of the above formulae, Gly stands for a glycine residue. Asp stands for an aspartic acid residue. Gin stands for a glutamine residue, Arg stands for an arginine residue, Lys stands for a lysine residue, lie stands for an isoleucine residue. Leu stands for a leucine residue, Phe stands for a phenylalanine residue, Tyr stands for a tyrosine residue, Trp stands for a tryptophan residue, and Ser stands for a serine residue. Amino acid sequences are indicated by the triplet code of IUPAC. The peptides provided by the present invention include the following peptides: H-Arg-Ile-Lys-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH 2 (1) H-Arg-Ile-Lys-Ile-Gly-Leu-Tyr-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (2) H-Arg-Ile-Lys-Ile-Gly-Leu-Trp-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (3) H-Arg-Ile-Lys-Ile-Gly-Ile-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (4) H-Arg-Ile-Lys-Ile-Gly-Ile-Tyr-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (5) H-Arg-Ile-Lys-Ile-Gly-Ile-Trp-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (6) H-Arg-Ile-Lys-Leu-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (7) H-Arg-Ile-Lys-Leu-Gly-Leu-Tyr-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (8) H-Arg-Ile-Lys-Leu-Gly-Leu-Trp-Asp-Gln-Leu-Ser-Lys-Leu-NH 2 ( 9 ) H-Arg-Ile-Lys-Leu-Gly-Ile-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH 2 (10) H-Arg-Ile-Lys-Leu-Gly-Ile-Tyr-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (11) H-Arg-Ile-Lys-Leu-Gly-Ile-Trp-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (12) H-Arg-Ile-Arg-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (13) H-Arg-Ile-Arg-Ile-Gly-Leu-Tyr-Asp-Gln-Leu-Ser-Lys-Leu-NH 2 (14) H-Arg- -Ile-Arg- Ile-Gly-Leu- Trp-Asp- Gin -Leu ■ ■ Ser-Lys- Leu-NH2 H-Arg- ■ Ile-Arg- Ile-Gly-Ile- Phe-Asp- Gin -Leu • ■ Ser -Lys - Leu-NH 2 H-Arg- ■ Ile-Arg- Ile-Gly-Ile- Tyr-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Ile-Gly-Ile- Trp-Asp- Gin-Leu- ■ Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Leu-Gly-Leu- Phe-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Leu-Gly-Leu- Tyr-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Leu-Gly-Leu- Trp-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Leu-Gly- Ile- Phe-Asp- Gin -Leu • • Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Leu-Gly-Ile- Tyr-Asp- Gin -Leu ■ • Ser -Lys - Leu-NH2 H-Arg- ■ Ile-Arg- Leu-Gly-Ile- Trp-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH 2 H-Arg- - Leu -Lys - Ile-Gly-Leu- Phe-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH 2 H-Arg- ■ Leu -Lys - Ile-Gly-Leu- Tyr-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH 2 H-Arg- ■ Leu -Lys - Ile-Gly-Leu- Trp-Asp- Gin -Leu ■ - Ser -Lys - Leu-NH2 H-Arg- - Le -Lys - Ile-Gly- Ile- Phe-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH 2 H-Arg- ■ Leu -Lys - Ile-Gly- Ile- Tyr-Asp- Gin -Leu • ■ Ser -Lys - Leu-NH2 H-Arg- -Leu-Lys- Ile-Gly- Ile- Trp-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH 2 H-Arg- -Leu-Lys- Leu-Gly-Leu- Phe-Asp- Gin-Leu- ■ Ser -Lys - Leu-NH 2 H-Arg- ■ Leu-Lys- Leu-Gly-Leu- Tyr-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH2 H-Arg -Leu-Lys- Leu-Gly-Leu- Trp-Asp- Gin -Leu ■ ■ Ser -Lys - Leu-NH 2 H-Arg ■ Leu -Lys - Leu-Gly-Ile- Phe-Asp- Gin -Leu ■ - Ser -Lys - Leu-NH 2 H-Arg - Leu -Lys - Leu-Gly- Ile- Tyr-Asp- Gin -Leu ■ - Ser- Lys - Leu-NH2 H-Arg -Leu-Lys- Leu-Gly-Ile- Trp-Asp- Gin -Leu • - Ser -Lys - Leu-NH2 H-Arg -Leu-Arg- Ile-Gly-Leu- Phe-Asp- Gin-Leu- ■ Ser -Lys • Leu-NH H-Arg -Leu-Arg- Ile-Gly-Leu- Tyr-Asp- Gin-Leu- - Ser -Lys - Leu- H2 H-Arg -Leu-Arg- Ile-Gly-Leu- Trp-Asp- Gin -Leu - Ser -Lys • Leu-NH H-Arg -Leu-Arg- Ile-Gly- Ile- Phe -Asp- ■ Gin-Leu - Ser -Lys ■ Leu-NH H-Arg -Leu-Arg- Ile-Gly-Ile- Tyr-Asp- ■ Gin -Leu - Ser -Lys ■■ Leu-NH2 H-Arg -Leu-Arg- Ile-Gly- Ile- Trp-Asp- ■ Gin -Leu - Ser -Lys ■■ Leu-NH 2 H-Arg -Leu-Arg- Leu-Gly-Leu- •Phe-Asp- ■ Gin-Leu - Ser -Lys ■■ Leu-NH 2 H-Arg -Leu-Arg- ■ Leu-Gly-Leu- ■ Tyr-Asp- ■ Gin -Leu -Ser -Lys ■ Leu-NH 2 H-Arg -Leu-Arg- ■ Leu-Gly-Leu- ■ Trp -Asp ■ ■ Gin-Leu - Ser -Lys ■• Leu-NH2 H-Arg -Leu-Arg- ■ Leu-Gly-Ile- ■ Phe -Asp ■ ■ Gin -Leu -Ser-Lys- ■ Leu-NH 2 H-Arg -Leu-Arg- Leu-Gly-Ile- Tyr-Asp-Gin- Leu-Ser-Lys- Leu-NH2 H-Arg -Leu-Arg- Leu-Gly-Ile- Trp-Asp-Gin- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Ile-Gly-Leu- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Ile-Lys- Ile-Gly-Leu- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Ile-Gly-Leu- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Ile-Lys- Ile-Gly-Ile- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Ile-Gly-Ile- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Ile-Gly-Ile- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Leu-Gly-Leu- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Leu-Gly-Leu- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Leu-Gly-Leu- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Lys- Leu-Gly-Ile- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Ile-Lys- Leu-Gly-Ile- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH H-Lys -Ile-Lys- Leu-Gly-Ile- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Ile-Gly-Leu- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Ile-Arg- Ile-Gly-Leu- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Ile-Gly-Leu- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Ile-Gly-Ile- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Ile-Gly-Ile- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Ile-Gly-Ile- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-Leu- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH H-Lys -Ile-Arg- Leu-Gly-Leu- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-Leu- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Ile-Arg- Leu-Gly-Ile- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-Ile- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Ile-Arg- Leu-Gly-Ile- Trp-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Leu-Lys- Ile-Gly-Leu- Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Leu-Lys- Ile-Gly-Leu- Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Leu-Lys- Ile-Gly-Leu- Trp-Asp-Gln- Leu-Ser-Lys- Le -NH2 H-Lys -Leu-Lys ■ Ile-Gly-Ile- ■ Phe-Asp-Gln- Leu-Ser-Lys- Leu-NH2 H-Lys -Leu-Lys ■ Ile-Gly-Ile- ■ Tyr-Asp-Gln- Leu-Ser-Lys- Leu-NH 2 H-Lys -Leu-Lys-•Ile-Gly-Ile-■Trp-Asp-Gln- Leu-Ser-Lys- • Leu-NH H-•Lys-Leu ■ -Lys-Leu- Gly-Leu- Phe-Asp- Gin-Leu ■■ Ser-Lys- Leu-NH2 (79) H- ■ Lys-Leu ■ -Lys-Leu- Gly-Leu- Tyr-Asp- Gin-Leu- -Ser-Lys- Leu-NH 2 (80) H- ■ Lys-Leu ■ -Lys-Leu- Gly-Leu- Trp-Asp- Gin-Leu• •Ser-Lys- Leu-NH 2 (81) H- ■ Lys-Leu ■ -Lys-Leu- Gly-Ile- Phe-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH 2 (82) H-•Lys-Leu•-Lys-Leu- Gly-Ile- Tyr-Asp- Gi -Leu• ■ Ser-Lys- Leu-NH2 (83) H- ■ Lys-Leu ■ -Lys-Leu- Gly-Ile- Trp-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH 2 (84) H- ■ Lys-Leu ■ -Arg-Ile- Gly-Leu- Phe-Asp- Gin-Leu• ■ Ser-Lys- Leu-NH2 (85) H-•Lys-Leu ■ -Arg-Ile- Gly -Leu- Tyr-Asp- Gin-Leu• ■ Ser-Lys- Leu-NH 2 (86) H- ■ Lys-Leu ■ -Arg-Ile- Gly-Leu - Trp-Asp- Gin-Leu ■ -Ser-Lys- Leu-NH 2 (87) H- ■ Lys-Leu ■ -Arg-Ile- Gly- Ile- Phe-Asp- Gin-Leu• ■ Ser-Lys- Leu-NH 2 (88) H- ■ Lys-Leu ■ -Arg-Ile- Gly- Ile- Tyr-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH 2 (89) H- • Lys-Leu ■ -Arg-Ile- Gly- Ile- Trp-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH2 (90) H- ■ Lys-Leu•-Arg-Leu- Gly-Leu- Phe-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH 2 (91) H- ■ Lys-Leu•-Arg-Leu- Gly-Leu- Tyr-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH 2 (92) H- ■ Lys-Leu ■ -Arg-Leu- Gly-Leu- Trp-Asp- Gin-Leu- •Ser-Lys- Leu-NH 2 (93) H- ■ Lys-Leu -Arg-Leu- Gly-Ile- Phe-Asp- Gin-Leu ■ ■ Ser-Lys- Leu-NH 2 (94) H--Lys-Leu -Arg-Leu- Gly- Ile- Tyr-Asp- Gin-Leu ■ •Ser-Lys- Leu-NH 2 (95) H--Lys-Leu -Arg-Leu- Gly- Ile - Trp-Asp- Gin-Leu--Ser-Lys- Leu-NH2 (96) H--Arg-Ile -Lys-Ile- Gly -Leu- Phe-Asp- Gin-Leu • -Ser-Arg- Leu-NH2 (97) H--Arg-Ile -Lys-Ile- Gly-Leu - Tyr-Asp- Gin-Leu--Ser-Arg- Leu-NH 2 (98) H--Arg-Ile -Lys-Ile- Gly-Leu- Trp-Asp- Gin-Leu--Ser-Arg- Leu-NH 2 (99) H -Arg-Ile -Lys-Ile- Gly- Ile- Phe-Asp- Gin-Leu -Ser-Arg- Leu-NH (100) H -Arg-Ile -Lys-Ile- ■ Gly-Ile- Tyr-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 (101) H -Arg-Ile -Lys-Ile- ■ Gly- Ile- ■ Trp-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 (102) H -Arg-Ile -Lys-Leu- Gly-Leu - ■ Phe-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 (103) H -Arg-Ile -Lys-Leu• ■ Gly-Leu-•Tyr-Asp- Gin-Leu -Ser-Arg- ■ Leu-NH2 (104) H -Arg-Ile -Lys-Leu• ■ Gly -Leu ■■ Trp-Asp- Gin-Leu -Ser-Arg- ■ Leu-NH2 (105) H -Arg-Ile -Lys-Leu ■ -Gly- He- ■ Phe-Asp-•Gi -Leu -Ser-Arg- ■ Leu-NH (106) H -Arg-Ile -Lys-Leu ■ -Gly- He ■■ Tyr-Asp- ■ Gin-Leu -Ser-Arg ■■ Leu-NH2 (107) H -Arg-Ile - Lys -Leu- -Gly- He--Trp-Asp- ■ Gi -Leu -Ser-Arg ■■ Leu-NH 2 (108) H -Arg-Ile -Arg-Ile - Gly -Leu ■ -Phe-Asp- ■ Gin-Leu -Ser-Arg ■■ Leu-NH2 (109) H-Arg-Ile -Arg-Ile -Gly-Leu--Tyr-Asp- ■ Gin-Leu -Ser-Arg--Leu-NH 2 (HO) H-Arg- ■ Ile-Arg- Ile-Gly-Leu- ■ Trp -Asp -Gin - Leu-Ser-Arg- -Leu-NH 2 H-Arg- ■ Ile-Arg- Ile-Gly- Ile- ■ Phe -Asp -Gin - Leu -Ser -Arg ■ -Leu-NH2 H-Arg- ■ Ile-Arg- Ile-Gly- Ile- ■ Tyr -Asp -Gin - Leu-Ser-Arg- ■ Leu-NH2 H-Arg- ■ Ile-Arg- Ile-Gly- He- ■ Trp-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- ■ Ile-Arg- Leu -Gly -Leu- ■ Phe-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- ■ Ile-Arg- Leu- Gly -Leu- ■ Tyr-Asp-Gln- Leu-Ser-Arg- ■ Leu-NH 2 H-Arg- • Ile-Arg- Leu-Gly-Leu- -Trp-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- •Ile-Arg- Leu-Gly-Ile- -Phe-Asp-Gln- Leu-Ser-Arg- ■ Leu-NH2 H-Arg- -Ile-Arg- Leu-Gly-Ile- -Tyr-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- ■ Ile-Arg- Leu-Gly- Ile- -Trp-Asp-Gln- Leu-Ser-Arg- ■ Leu-NH 2 H-Arg- • Leu -Lys - Ile-Gly-Leu- -Phe-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- ■ Leu -Lys - Ile-Gly-Leu- -Tyr-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- - Leu -Lys - Ile-Gly-Leu- -Trp-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- ■ Leu -Lys - Ile-Gly-Ile- -Phe-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- ■ Leu -Lys - Ile-Gly-Ile- -Tyr-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- ■ Leu-Lys- Ile-Gly- He- -Trp-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- - Leu -Lys - Leu -Gly -Leu -Phe-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- - Leu -Lys - Leu-Gly-Leu -Tyr-Asp-Gln- Leu-Ser-Arg- -Leu-NH 2 H-Arg- -Leu-Lys- Leu-Gly-Leu -Trp-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- - Leu -Lys - Leu-Gly- Ile -Phe-Asp-Gln- Leu-Ser-Arg- -Leu-NH2 H-Arg- - Leu -Lys - Leu-Gly- Ile -Tyr-Asp-Gln- Leu-Ser-Arg -Leu-NH 2 H-Arg -Leu-Lys- Leu-Gly-Ile -Trp-Asp-Gln- Leu-Ser-Arg -Leu-NH 2 H-Arg -Leu-Arg- Ile-Gly-Leu -Phe-Asp-Gln- Leu-Ser-Arg -Leu-NH2 H-Arg -Leu-Arg- Ile-Gly-Leu -Tyr-Asp-Gln- Leu-Ser-Arg -Leu-NH H-Arg -Leu-Arg- Ile-Gly-Leu -Trp-Asp-Gln- Leu-Ser-Arg -Leu-NH 2 H-Arg -Leu-Arg- •Ile-Gly-Ile -Phe-Asp-Gln- Leu-Ser-Arg -Leu-NH2 H-Arg - Leu-Arg- Ile-Gly- Ile -Tyr-Asp-Gln- Leu-Ser-Arg -Leu-NH 2 H-Arg -Leu-Arg- •Ile-Gly- Ile -Trp-Asp-Gln- Leu-Ser-Arg -Leu-NH2 H-Arg - Leu-Arg- •Leu-Gly-Leu -Phe-Asp-Gln- •Leu-Ser-Arg -Leu-NH 2 H-Arg -Leu-Arg- •Leu-Gly-Leu -Tyr-Asp-Gln- ■ Leu-Ser-Arg -Leu-NH 2 H-Arg -Leu-Arg- ■ Leu-Gly-Leu -Trp-Asp-Gln- ■ Leu-Ser-Arg -Leu-NH H-Arg -Leu-Arg- -Leu-Gly-Ile -Phe-Asp-Gln- ■ Leu-Ser-Arg -Leu-NH2 H-Arg- -Leu-Arg- Leu-Gly-Ile- Tyr-Asp- Gin-Leu ■ -Ser-Arg- Leu-NH2 H-Arg- -Leu-Arg- Leu-Gly-Ile- Trp-Asp- Gin-Leu•-Ser-Arg- Leu-NH 2 H-Lys- -Ile-Lys- Ile-Gly-Leu- Phe-Asp- Gin-Leu--Ser-Arg- Leu-NH 2 H-Lys- - Ile-Lys- Ile-Gly-Leu- Tyr-Asp- Gin-Leu ■ -Ser-Arg- Leu-NH2 H-Lys -Ile-Lys- Ile-Gly-Leu- Trp-Asp- Gin-Leu•-Ser-Arg- Leu-NH 2 H-Lys- - Ile-Lys- Ile-Gly-Ile- Phe-Asp- Gin-Leu ■■ Ser-Arg- Leu-NH 2 H-Lys- - Ile-Lys- Ile-Gly-Ile- Tyr-Asp- Gin-Leu ■ ■ Ser-Arg- Leu-NH H-Lys- -Ile-Lys- Ile-Gly- He- Trp-Asp- Gin-Leu ■ ■Ser-Arg- Leu-NH 2 H-Lys -Ile-Lys- Leu -Gly -Leu- Phe-Asp- Gin-Leu ■■ Ser-Arg- Leu-NH2 H-Lys -Ile-Lys- Leu- Gly -Leu - Tyr-Asp- Gin-Leu ■ -Ser-Arg- Leu-NH 2 H-Lys -Ile-Lys- Leu-Gly-Leu- Trp-Asp- Gin-Leu■ ■Ser-Arg- Leu-NH 2 H-Lys -Ile-Lys- Leu-Gly-He- Phe-Asp- Gin-Leu ■ ■Ser-Arg- Leu-NH H-Lys -Ile-Lys- Leu-Gly- He- Tyr-Asp- Gin-Leu ■ ■ Ser-Arg- Leu-NH2 H-Lys -Ile-Lys- Leu-Gly-He- Trp-Asp- Gin-Leu■-Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- He-Gly-Leu- Phe-Asp- Gin-Leu-■Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- He-Gly-Leu- Tyr-Asp- Gin-Leu- ■Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- He-Gly-Leu- Trp-Asp- Gin-Leu- ■ Ser-Arg- Leu-NH2 H-Lys -Ile-Arg- He-Gly- He- Phe-Asp- Gin-Leu--Ser-Arg- Leu-NH2 H-Lys -Ile-Arg- He-Gly-He- Tyr-Asp- Gin-Leu--Ser-Arg- Leu-NH2 H-Lys -Ile-Arg- He-Gly-He- Trp-Asp- Gin-Leu--Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-Leu- Phe-Asp- Gin-Leu--Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-Leu- Tyr-Asp- Gin-Leu--Ser-Arg- Leu-NH H-Lys -Ile-Arg- Leu-Gly-Leu- Trp-Asp- Gin-Leu- -Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-He- Phe-Asp- Gin-Leu -Ser-Arg- Leu-NH2 H-Lys -Ile-Arg- Leu-Gly-He- Tyr-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 H-Lys -Ile-Arg- Leu-Gly-He- Trp-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 H-Lys -Leu-Lys- Ile-Gly-Leu- Phe-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 H-Lys - Leu -Lys ■ ■ Ile-Gly-Leu ■ Tyr-Asp- Gin-Leu -Ser-Arg- Le -NH2 H-Lys -Leu-Lys- ■ Ile-Gly-Leu-•Trp-Asp- Gin-Leu -Ser-Arg- Leu-NH H-Lys -Leu-Lys- ■ Ile-Gly-Ile- ■ Phe-Asp- Gin-Leu -Ser-Arg ■ Leu-NH2 H-Lys -Leu-Lys- ■ Ile-Gly-Ile-•Tyr-Asp- Gin-Leu -Ser-Arg- Leu-NH 2 H-Lys -Leu-Lys- •Ile-Gly-Ile- ■ Trp-Asp-■Gin-Leu -Ser-Arg- Leu-NH2 H-Lys- Leu-Lys -Leu-Gly-Leu- Phe-Asp-Gln-Leu-Ser- Arg-Leu-NH2 175) H-Lys - Leu-Lys -Leu-Gly-Leu- Tyr-Asp-Gln-Leu-Ser- Arg-Leu-NH2 176) H-Lys - Leu-Lys -Leu-Gly-Leu- Trp-Asp-Gln-Leu-Ser- Arg-Leu-NH2 177) H-Lys - Leu-Lys -Leu-Gly-He- Phe-Asp-Gln-Leu-Ser- Arg-Leu-NH2 178) H-Lys - Leu-Lys -Leu-Gly-He- Tyr-Asp-Gln-Leu-Ser- Arg-Leu-NH2 179) H-Lys - Leu-Lys -Leu-Gly-He- Trp-Asp-Gin-Leu-Ser- Arg-Leu-NH2 180) H-Lys - Leu-Arg -Ile-Gly-Le - Phe-Asp-Gln-Leu-Ser- Arg-Leu-NH2 181) H-Lys - Leu-Arg -Ile-Gly-Leu- Tyr-Asp-Gin-Le -Ser- Arg-Leu-NH2 182) H-Lys - Leu-Arg -Ile-Gly-Leu- Trp-Asp-Gin-Leu-Ser- Arg-Leu-NH2 183) H-Lys - Leu-Arg -Ile-Gly-Ile- Phe-Asp-Gln-Leu-Ser- Arg-Leu-NH2 184) H-Lys - Leu-Arg -He-Gly-He- Tyr-Asp-Gln-Leu-Ser- Arg-Leu-NH2 185) H-Lys - Leu-Arg -He-Gly-He- Trp-Asp-Gln-Leu-Ser- Arg-Leu-NH2 186) H-Lys - Leu-Arg -Leu-Gly-Leu- Phe-Asp-Gln-Leu-Ser- Arg-Leu-NH2 187) H-Lys - Leu-Arg -Leu-Gly-Leu- Tyr-Asp-Gln-Leu-Ser- Arg-Leu-NH2 188) H-Lys - Leu-Arg -Leu-Gly-Leu- Trp-Asp-Gln-Leu-Ser- Arg-Leu-NH2 189) H-Lys - Leu-Arg -Leu-Gly-He- Phe-Asp-Gln-Leu-Ser- Arg-Leu-NH2 190) H-Lys - Leu-Arg -Leu-Gly-He- Tyr-Asp-Gln-Leu-Ser- Arg-Leu-NH2 191) H-Lys - Leu-Arg -Leu-Gly-He- Trp-Asp-Gln-Leu-Ser- Arg-Leu-NH2 192) In order to obtain the peptides of the present invention, for example, venom sac of a solitary wasp containing said peptides may be excised and then homogenized in a water- containing organic solvent, and the resulting homogenate may be centrifuged to obtain a supernatant, which may be purified by a reversed phase chromatography until finally it exhibits a single peak when monitored by UV absorbance at 215 nm, thereby isolating and purifying the desired compound. The water-containing organic solvent to be used for the homogenization during the above purification process means a mixture of water and an organic solvent that is freely miscible with water, and may be any solvent which permits extraction of the compound of the present invention. Examples include, but not limited to, water-containing acetone, water-containing acetonitrile, and the like. When the resulting supernatant is directly applied to the reversed phase chromatography, it is preferred that about 0.1% of trifluoroacetic acid (hereinafter referred to as TFA) is added to such a water-containing organic solvent . Since the peptides provided by the present invention consist of at most about 13 amino acids, they can be synthesized by the conventional liquid or solid phase method. Furthermore, since the peptides of the present invention are basic peptides, they can be converted to appropriate acid-added salts according to conventional technique. Such preferred acid-added salts may be obtained by reaction with a pharmaceutically acceptable acid, and said salts include, for example, lactates, acetates, succinates, maleates, fumarates, tartarates, citrates, gluconates, ascorbates, benzoates, methanesulfonates , cinnamates, benzenesulfonates or phosphates, hydrogenphosphates , hydrochlorides , hydrobromides , hydroiodides , sulfamates, sulfates, trifluoroacetates , and the like. The biological activity of the present peptides can be assayed according to the methods described in Japanese Patent Laid-Open No. 4-198161, in which excitatory postsynaptic potential (EPSP) is generated in the neuromuscular specimen of a lobster's walking leg, and the effect of the compound given to the nerve fibers on the EPSP is determined. In general, substances inhibiting EPSP are believed to be glutamate antagonists or inhibitors for the release of glutamic acid, and the substances enhancing EPSP are believed to be glutamate-like agonists or accelerators for the release of glutamic acid. As described in the Examples below, the peptides of the present invention show a remarkable effect of enhancing EPSP determined by the above assay. Accordingly, the compounds of the present invention are useful for enhancing cerebral neural activities and recovering muscular strength in the treatment of neuromuscular diseases. They are also useful as a tool for the study of neuroscience toward the elucidation of the transmission mechanism. The present invention is now illustrated in more detail by way of the following examples, but it is to be noted that the present invention is not limited by these Examples in any way. Example 1: Isolation and structure determination of peptides (1) and (97) 11 Isolation of peptide (1) The venom sacs of 60 female Anoplius samariensis were excised and lyophilized. These were homogenized in 1 ml of 50% acetonitrile/water containing 0.1% TFA and then centrifuged to obtain an extract. The precipitate was centrifuged again with 1 ml of 50% acetonitrile/water containing 0.1% TFA. This procedure was then repeated four times. All the extracts resulting from the above procedure carried out five times in total were collected and then evaporated under reduced pressure to obtain a crude extract . The resulting crude extract was dissolved in water and then subjected to reversed phase HPLC (Waters Associates) using CAPCELL PAK C 18 Φ 10 mm X 250 mm (Shiseido Co., Ltd.,) with linear gradient from 5% to 95% acetonitrile/water containing 0.1% TFA at a flow rate of 2.5 ml/min over 30 minutes at room temperature. The peak fraction at a retention time of 19 min was collected by monitoring UV absorbance at 215 nm. The obtained peak fraction was further subjected to HPLC using CAPCELL PAK C 8 Φ 6 mm X 150 mm (Shiseido Co., Ltd..) with isocratic 29% acetonitrile/water containing 0.1% TFA at a flow rate of 1 ml/min at room temperature, and the peak fraction at a retention time of 15 min was collected by monitoring UV absorbance at 215 nm. This fraction showed a single peak at a retention time of 11 min in HPLC using the above column (isocratic 30% acetonitrile/water containing 0.1% TFA). The resulting fraction was lyophilized to yield 0.1 mg of peptide (1) as a trifluoroacetate. 2 ) Isolation of peptide (97) The venom sacs of 29 female Batozonellus maculifrons were excised and lyophilized. These were homogenized in 0.5 ml of 50% acetonitrile/water containing 0.1% TFA and then centrifuged to obtain an extract . The precipitate was centrifuged again with 0.5 ml of 50% acetonitrile/water containing 0.1% TFA. This procedure was then repeated four times. All the extracts resulting from the above procedure carried out five times in total were collected and then evaporated under reduced pressure to obtain a crude extract . The resulting crude extract was dissolved in water and then subjected to reversed phase HPLC using CAPCELL PAK Ci8 Φ 10 mm x 250 mm with linear gradient from 5% to 95% acetonitrile/water containing 0.1% TFA at a flow rate of 2.5 ml/min over 30 minutes at room temperature. The peak fraction at a retention time of 19 min was collected by monitoring UV absorbance at 215 nm. The obtained peak fraction was further subjected to HPLC using CAPCELL PAK C^s Φ 6 mm X 150 mm with isocratic 29% acetonitrile/water containing 0.1% TFA at a flow rate of 1 ml/min at room temperature, and the peak fractions at a retention time of 15 min and 16 min were collected by monitoring UV absorbance at 215 nm. The fraction obtained at a retention time of 15 min was lyophilized to yield 50 g of peptide (1) as a trifluoroacetate and the fraction obtained at a retention time of 16 min was lyophilized to yield 30 U g of peptide (97) as a trifluoroacetate. 3) Determination of the amino acid sequence The amino acid sequences of the resulting peptides were determined by mass spectroscopy and Edman degradation. Mass spectroscopy was conducted by the Ladder sequencing method using carboxypeptidase and aminopeptidase and by MALDI-TOF-MS combined with the CID method. Distinction of Leu from He and Lys from Gin was demonstrated by the automatic Edman degradation using ABI 477A/120A Protein Sequencer (Applied Biosystems). Furthermore, since a peak of m/z = 1530 (M+H) + was observed in MALDI-TOF-MS, peptide (1) was found to have a sequence represented by SEQ ID NO: 1 in which the N-terminal is free and the C-terminal is amidated. On the other hand, peptide (97) was identified with a sequence represented by SEQ ID NO: 2 by observing a peak of m/z=1558 (M+H) + in MALDI-TOF-MS. Example 2: Synthesis of peptides (1) and (97) Peptides (1) and (97) were synthesized using TGS-RAM-Resin (Shimadzu Corporation) as a carrier and Fmoc-amino acids in the solid phase method using the automatic peptide synthesizer PSSM-8 (Shimadzu Corporation). Each of the synthesized peptides was then cleaved from the peptide resin and deprotected by adding a TFA solution containing 5% phenol, 5% thioanisole, 5% water, 3% 1,2-ethanedithiol and 2% ethylmethyl disulfide in an amount of 10 ml per gram of the peptide resin and then treating it at room temperature for 8 hours. After the treatment, ether was added to the TFA solution to precipitate the peptides, and the precipitate was washed three times with ether to obtain crude peptides. The crude peptides were purified by C-18 reversed phase HPLC. The resulting synthetic peptides (1) and (97) showed the same retention time in HPLC, the same mass spectra, and the same biological activity as the natural peptides (1) and (97), respectively. Example 3: Measurement of the effect on excitatory postsynaptic potential (EPSP) The effect of the present peptides on excitatory postsynaptic potential (EPSP) was measured according to the method disclosed in Japanese Patent Laid-Open No. 4-198161. Thus, the shell of a lobster's walking leg was removed to expose the excitatory nerve and the inhibitory nerve, and a stimulating electrode was attached thereto. Then the nerve-muscle junction was exposed, and a recording electrode was attached thereto. The walking leg equipped with the electrodes was transferred to a container filled with an artificial seawater, and a partition was set up between the stimulating electrode part and the recording electrode part. The samples to be measured were dissolved into the artificial seawater in the recording electrode side (i.e., the side containing the nerve-muscle junction) . Subsequently, the excitatory nerve was electrically stimulated and the EPSP, which was induced by glutamic acid released from the nerve end in response to the stimulation, was recorded. When the effects of peptides (1) and (97) on EPSP were studied according to this method, peptide (1) enhanced EPSP at a concentration of 1X10 -6 M, and peptide (97) did at 2X10 "7 M. INDUSTRIAL APPLICABILITY The peptides provided by the present invention can be used as useful reagents to study the structure-activity relationship of their activities on the glutamate receptor in the field of neuroscience. Furthermore, they can be used as standard compounds in the study of neuroscience, especially in the study of neuropathic diseases such as Huntington's disease, epilepsy, Parkinson's disease and senile dementia, paving the way for pharmaceutical application of substances that act on the glutamate receptor.

Claims: CLAIMS 1. A peptide represented by the following amino acid sequence formula (A) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-R (A) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xβ independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and R represents -NH2 , -Leu-NH2, -Leu-Ser-NH2, -Leu-Ser-Lys-NH2 -Leu-Ser-Arg-NH2 f -Leu-Ser-Lys-Leu-NH2 or -Leu-Ser-Arg-Leu-NH2; and a salt thereof. 2. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (B) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-NH2 (B) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and X independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 3. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (C): H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-NH 2 (C) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and X independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 4. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (D) : H-X!-X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gin-Leu-Ser-NH 2 (D) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xβ independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 5. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (E) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-Ser-Lys-NH2 (E) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xβ independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 6. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (F) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gln-Leu-Ser-Arg-NH2 (F) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xβ independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 7. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (G) : H-X 1 -X 2 -X3-X4-Gly-X 6 -X7-Asp-Gln-Leu-Ser-Lys-Leu-NH 2 (G) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and X β independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 8. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (H) : H-Xi-X 2 -X3-X4-Gly-X 6 -X 7 -Asp-Gin-Leu-Ser-Arg-Leu-NH 2 (H) wherein: each of X^ and X3 independently represents Arg or Lys, each of X2, X4 and Xβ independently represents He or Leu, and X7 represents Phe, Tyr or Trp; and a salt thereof. 9. The peptide as claimed in claim 1 represented by the following amino acid sequence formula ( 1 ) : H-Arg-Ile-Lys-He-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Lys-Leu-NH2 (1) and a salt thereof. 10. The peptide as claimed in claim 1 represented by the following amino acid sequence formula (97): H-Arg-Ile-Lys-Ile-Gly-Leu-Phe-Asp-Gln-Leu-Ser-Arg-Leu-NH 2 (97) and a salt thereof. 11. The peptide and a salt as claimed in claim 1 as a glutamate receptor agonist. 12. A pharmaceutical composition containing the peptide as claimed in claim 1. 13. Use of the peptide as claimed in claim 1 for treatment of glutamate receptor related diseases. 14. A method for treatment of glutamate receptor related diseases which comprising administering an effective amount of the peptide as claimed in claim 1.

Inventors: ITAGAKI YASUHIRO, KAWAI NOBUFUMI, KONNO KATSUHIRO, TAKAYAMA HIROAKI, ITAGAKI, YASUHIRO, KAWAI, NOBUFUMI, KONNO, KATSUHIRO, TAKAYAMA, HIROAKI
Applicants: ITAGAKI YASUHIRO, KAWAI NOBUFUMI, KONNO KATSUHIRO, SUNTORY LTD, TAKAYAMA HIROAKI, ITAGAKI, YASUHIRO, KAWAI, NOBUFUMI, KONNO, KATSUHIRO, SUNTORY LIMITED, TAKAYAMA, HIROAKI
Application year: 1998
Main classification: C07K14
IPC codes: A61K38, A61P21, A61P25, A61P43, C07K7, C07K14