Formaldehyde-induced Cross-Linkages in the α Subunit of the Escherichia coli Tryptophan Synthetase

Abstract

Two intramolecular cross-linkages (methylene bridges) have been introduced by formaldehyde in the α subunit of the Escherichia coli tryptophan synthetase without any detectable loss in enzyme activity. These have been assigned to side chains in the sequences between residues 152 to 158, 212 to 218, and 227 to 233. Based on the conditions of reaction, the stability of the methylene bridges, and the availability of reactive residues in these sequences, the specific amino acid pairs linked together have been tentatively designated as asparagine-156-serine-214 and glutamine-218-serine-232.