Amino acid sequence of Escherichia coli alkaline phosphatase.

The complete amino acid sequence of the Escherichia coli alkaline phosphatase subunit [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1, isozyme 3] has been determined. The monomer contains 449 amino acid residues in a single unglycosylated polypeptide chain having a calculated Mr of 47,029. Isozyme 1 has an additional arginine residue at the NH2 terminus that presumably results from variability in processing of precursor molecules. Sequence data were obtained from both manual and automatic Edman degradation of the tryptic and cyanogen bromide peptides, as well as other peptides derived therefrom. The two disulfide bonds were determined from analyses of the appropriate peptic peptides. This structure confirms earlier reports of the sequence surrounding the active-site serine and both the NH2- and COOH-terminal cyanogen bromide fragments. A secondary structure prediction places nearly half the residues in alpha-helical segments that have 13% and 16%, respectively, in beta-strand and beta-turn orientations.