Complete amino acid sequence of luffin-b, a ribosome-inactivating protein from sponge gourd (Luffa cylindrica) seeds.
The complete amino acid sequence of luffin-b has been determined. All the twenty-seven tryptic peptides were isolated by reverse-phase HPLC from the tryptic digests of intact luffin-b and one of its CNBr fragments (CB4), and sequenced using the DABITC/PITC double coupling method. The overlap of these peptides was achieved by analyzing the CNBr fragments and their chymotryptic peptides. Luffin-b consists of 250 amino acid residues with a relative molecular mass of 27,275 Da. Investigation for glycosylation sites indicated that Asn at positions 2, 78, and 85 might carry sugars. Sequence comparison with luffin-a showed that amino acid substitution occurred in 55 positions. Luffin-b contains three glycosylation sites instead of the six sites in luffin-a, of which two were found to be conserved.
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Laboratory of Protein Chemistry and Engineering, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Hirayama
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Funatsu
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D003488:Cyanogen Bromide; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry*; D054789:Ribosome Inactivating Proteins, Type 1; D012270:Ribosomes / Q000187:drug effects*; D012639:Seeds / Q000032:analysis*; D009626:Terminology as Topic; D014357:Trypsin
D000596:Amino Acids; D010446:Peptide Fragments; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; C063258:luffin-a protein, Luffa cylindrica; C069038:luffin-b protein, Luffa cylindrica; D014357:Trypsin; D003488:Cyanogen Bromide