title: Primary structure of 6.5k-arginine/glutamate-rich polypeptide from the seeds of sponge gourd (Luffa cylindrica).
abstract: The amino acid sequence of 6.5k-arginine/glutamate rich polypeptide (6.5k-AGRP) from the seeds of sponge gourd (Luffa cylindrica) has been determined. The 6.5k-AGRP consists of a 47-residue polypeptide chain containing two disulfide bonds, and a molecular mass calculated to be 5695 Da, which fully coincides with a value of [M+H]+ = m/zeta 5693.39 obtained by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The mass spectrometric evidence indicated that 6.5k-AGRP is also present partially truncated at the C-terminus. In our preparations, approximately half of the polypeptide molecules have the C-terminal sequence Arg-Arg-Glu-Val-Asp; the other half lack Val-Asp and end with the glutamic acid, making a total of 45 residues in the polypeptide chain. The two disulfide bonds connect Cys12 to Cys33 and Cys16 to Cys29. Comparison of the amino acid sequence of 6.5k-AGRP with those of the other known proteins included in the PIR protein sequence database showed that it is related to the amino acid sequence of the N-terminal region encoded by the first exon of the cocoa (Theobroma cacao) and cotton seeds vicilin genes, sharing a characteristic two Cys-Xaa-Xaa-Xaa-Cys motif.
authors.affiliation: Laboratory of Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: S S
authors.initials: SS
authors.lastname: Park
authors.forename: R
authors.initials: R
authors.lastname: Sakai
authors.forename: N
authors.initials: N
authors.lastname: Yamasaki
authors.forename: G
authors.initials: G
authors.lastname: Funatsu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D018698:Glutamic Acid / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D012639:Seeds / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014675:Vegetables / Q000737:chemistry
chemical_list: D010455:Peptides; D010940:Plant Proteins; D018698:Glutamic Acid; D001120:Arginine; D012697:Serine Endopeptidases; C036813:lysyl endopeptidase