|
type |
Journal Article |
authors |
Nozaki H, Kuroda S, Watanabe K, Yokozeki K. |
title |
Screening of microorganisms producing α-methylserine hydroxymethyltransferase, purification of the enzyme, gene cloning, and application to the enzymatic synthesis of α-methyl-l-serine |
journal |
J. Mol. Catal. B: Enzym. |
Activity |
2.1.2.7 |
Family |
2.1.2.7.a |
sel |
selected |
ui |
JMolCatal56221 |
year |
(2009) |
volume |
56 |
number |
4 |
pages |
221-6 |
| |
keywords |
doi: 10.1016/j.molcatb.2008.05.002 |
abstract |
Through the screening of microorganisms capable of utilizing α-methylserine, three representative strains belonging to the bacterial genera Paracoccus, Aminobacter, and Ensifer were selected as potent producers of α-methylserine hydroxymethyltransferase, an enzyme that catalyzes the interconversion between α-methyl-l-serine and d-alanine via tetrahydrofolate. Among these strains, Paracoccus sp. AJ110402 was selected as the strain exhibiting the highest α-methylserine hydroxymethyltransferase activity. The enzyme was purified to homogeneity from a cell-free extract of this strain. The native enzyme is a homodimer with apparent molecular mass of 85 kDa and contains 1 mol of pyridoxal-5′-phosphate per mol of the subunit. The Km for α-methyl-l-serine and tetrahydrofolate was 0.54 mM and 73 μM, respectively. The gene from Paracoccus sp. AJ110402 encoding α-methylserine hydroxymethyltransferase was cloned and expressed in Escherichia coli. Sequence analysis revealed an open reading frame of 1278 bp, encoding a polypeptide with a calculated molecular mass of 46.0 kDa. Using E. coli cells as whole-cell catalysts, 9.7 mmol of α-methyl-l-serine was stereoselectively obtained from 15 mmol of d-alanine and 13.2 mmol of formaldehyde. |
last changed |
2018/11/22 11:46 |
|