Sequence Studies on d‐Serine Dehydratase of Escherichia coli

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Abstract
An improved procedure for large-scale production of crystalline D-serine dehydratase (EC 4.2.1.14) from E. coli is described. The N-terminal sequence of the enzyme (MW 45,500) was determined in a solid-phase sequencer as Met-Glu-Asn-Ala-Lys-Met-Asn-Ser-Leu-Ile-Ala-Gln-Tyr-Pro-Leu-Val-Lys-Asp-Leu-Val-Ala-Leu-Lys. Four of the first 5 N-terminal residues are homologous with tryptophanase, another pyridoxal-phosphate (P-Pxy) enzyme that catalyzes .alpha.,.beta.-elimination reactions. After borohydride reduction and tryptic digestion of the enzyme, a peptide was isolated showing the sequence Lys-Asp-Ser-His-Leu-Pro-Ile-Ser-Gly-Ser-Gly-Ser-Ile-Lys(P-Pxy)-Ala-Arg. No clear homology of this portion of the enzyme with tryptophanase or another pyridoxal-phosphate enzyme was observed.