title: Identification of lysine residue at or near active site of luffin-a, a ribosome-inactivating protein from seeds of Luffa cylindrica.
abstract: Luffin-a, a ribosome-inactivating protein from the seeds of sponge gourd (Luffa cylindrica), was modified with 2,4,6-trinitrobenzenesulfonic acid (TNBS) at pH 8.0 and 20 degrees C. The inhibitory activity of the modified luffin-a on protein synthesis using rabbit reticulocyte lysate was lost rapidly at a rate compatible with that of the modification of a single highly reactive amino group in the initial stage of the reaction. By cation-exchange FPLC of the products of 5-min modification, TNP-luffin-a containing one modified amino group was obtained and shown to have only 6.7% of the activity of native luffin-a without any gross conformational change. The amino acid composition and sequence of the TNP-peptide, isolated by reverse-phase HPLC of the tryptic digest of the TNP-luffin-a, unambiguously demonstrate the trinitrophenylation of lysine residue at position 231. From these results, it was concluded that Lys231 of luffin-a is highly reactive to TNBS and is located at or near the active site of luffin-a.
authors.affiliation: Laboratory of Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka.
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Suemasu
authors.forename: G
authors.initials: G
authors.lastname: Funatsu
mesh_terms: D000596:Amino Acids; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D008239:Lysine; D015394:Molecular Structure; D010446:Peptide Fragments; D010940:Plant Proteins / Q000378:metabolism*; D054789:Ribosome Inactivating Proteins, Type 1; D012639:Seeds; D014302:Trinitrobenzenesulfonic Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; C063258:luffin-a protein, Luffa cylindrica; D014302:Trinitrobenzenesulfonic Acid; D008239:Lysine