The complete primary structure of protein synthesis inhibitor II from barley seeds

The complete amino acid sequence of the barley translation inhibitor II has been determined. Peptide fragments were generated by cleavage with either cyanogen bromide, hydroxylamine, o-iodosobenzoic acid, S. aureus V8 protease, endoproteinase Lys-C, clostripain, or trypsin. The fragments were separated by gel filtration and RP-HPLC and subjected to automated liquid phase sequencing, gas-phase sequencing or mass spectrometry. The translation inhibitor possessed a blocked N-terminus identified as acetylated alanine by mass spectrometry of an N-terminally blocked tetrapeptide generated by cleavage with cyanogen bromide. Barley translation inhibitor II consists of 280 amino acid residues in a single chain and shows a distant homology to the ricin A-chain.