Mass spectrometric determination of the radical scission site in the anaerobic ribonucleotide reductase of Escherichia coli.
Active anaerobic ribonucleotide reductase from Escherichia coli contains an oxygen sensitive organic radical, proposed to reside on glycine-681 at the C-terminal end of the polypeptide chain. Exposure of the radical containing enzyme to oxygen results in cleavage of the molecule at the site of the hypothetical radical. We determined by mass spectrometry the size of the complete and the C-terminal-processed polypeptides. The difference in size between the two molecules shows that cleavage occurs at the N-terminal side of glycine-681, demonstrating that the organic radical is indeed located on this amino acid residue.
King
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Howard Hughes Medical Institute, Department of Molecular Biology, University of California, Berkeley 94720.
Reichard
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D000595:Amino Acid Sequence; D000693:Anaerobiosis; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D005998:Glycine; D013058:Mass Spectrometry; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D012264:Ribonucleotide Reductases / Q000737:chemistry* / Q000378:metabolism
D010446:Peptide Fragments; D012264:Ribonucleotide Reductases; D005998:Glycine