Isolation and amino acid sequence of a protein-synthesis inhibitor from the seeds of rye (Secale cereale).
A protein-synthesis inhibitor, designated RPSI, was isolated from the seeds of rye (Secale cereale) using gel filtration and S-Sepharose column chromatography. RPSI is a basic protein with an isoelectric point of over 10, and the concentration of protein required for 50% inhibition of protein synthesis (IC50) of purified RPSI was about ten-fold the concentration of ricin A-chain. The complete amino acid sequence of RPSI was discovered by analyzing the peptides and fragments obtained from the proteolytic digests and by the cyanogen bromide- and hydroxylamine-cleavages of RPSI. RPSI consists of 280 amino acid residues and has a molecular weight of 30,171. RPSI has only 21% sequence identity with that of ricin A-chain, but all five amino acid residues involved in the active site of ricin A-chain are conserved in RPSI.
Minami
Y
Y
Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Japan.
Yamaguchi
K
K
Yagi
F
F
Tadera
K
K
Funatsu
G
G
D000595:Amino Acid Sequence; D002847:Chromatography, Agarose; D002850:Chromatography, Gel; D002918:Chymotrypsin; D003488:Cyanogen Bromide; D006868:Hydrolysis; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D037121:Plant Lectins; D011500:Protein Synthesis Inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D012276:Ricin / Q000737:chemistry*; D012434:Secale / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D014357:Trypsin
D010446:Peptide Fragments; D037121:Plant Lectins; D011500:Protein Synthesis Inhibitors; D012276:Ricin; D002918:Chymotrypsin; D014357:Trypsin; D003488:Cyanogen Bromide