A high-resolution reference map for cytoplasmic and membrane-associated proteins ofCorynebacterium glutamicum

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Abstract
We present a high‐resolution reference map for soluble proteins obtained from Corynebacterium glutamicum cells grown in glucose minimal medium. The analysis window covers the pIrange from 4–6 and the molecular mass range from 5–100 kDa. Using overlapping narrow immobilized pH gradients for isoelectric focusing, 970 protein spots were detected after second‐dimensional separation on SDS‐polyacrylamide gels and colloidal Coomassie‐staining. By tryptic peptide mass fingerprinting 169 protein spots were identified, representing 152 different proteins including many enzymes involved in central metabolism (18), amino acid biosynthesis (24) and nucleotide biosynthesis (11). Thirty‐five of the identified proteins have no known function. A comparison of the observed and the expected physicochemical properties of the identified proteins indicated that nine proteins were covalently modified, since variants with apparently identical molecular mass, but differing pI were detected. The N‐termini of eight proteins were determined by post‐source decay (PSD) analysis of selected peptides. In addition to the soluble proteins, a map of the membrane‐bound proteins within the pI range 4–7 is presented, which contains 660 protein spots, 22 of which were identified, representing 13 different proteins.