The primary structure of Escherichia coli K12 aspartokinase I-homoserine dehydrogenase I-Isolation and characterisation of the peptides produced by cyanogen bromide.

The aspartokinase I-homoserine dehydrogenase I from Escherichia coli K12, composed of four identical subunits of molecular weight 86,000, was carboxy-methylated, fragmented by cyanogen bromide treatment and citraconylated. Using gel filtration, ion exchange chromatography and preparative paper electrophoresis and chromatography, 15 of 21 cyanogen bromide peptides were isolated in pure form and characterized by their composition, their N-terminal amino acid, and by their content of known cysteinyl or tryptophanyl tryptic peptides.