Jump to main content
US EPA
United States Environmental Protection Agency
Search
Search
Main menu
Environmental Topics
Laws & Regulations
About EPA
Health & Environmental Research Online (HERO)
Contact Us
Print
Feedback
Export to File
Search:
This record has one attached file:
Add More Files
Attach File(s):
Display Name for File*:
Save
Citation
Tags
HERO ID
1000088
Reference Type
Journal Article
Title
Characterization of a thermostable methylaspartate ammonia lyase from Carboxydothermus hydrogenoformans
Author(s)
Raj, H; Puthan Veetil, V; Szymanski, W; Dekker, FJ; Quax, WJ; Feringa, BL; Janssen, DB; Poelarends, GJ
Year
2012
Is Peer Reviewed?
Yes
Journal
Applied Microbiology and Biotechnology
ISSN:
0175-7598
EISSN:
1432-0614
Volume
94
Issue
2
Page Numbers
385-397
Language
English
PMID
22005738
DOI
10.1007/s00253-011-3615-6
Abstract
Methylaspartate ammonia lyase (MAL; EC 4.3.1.2) catalyzes the reversible addition of ammonia to mesaconate to give (2S,3S)-3-methylaspartate and (2S,3R)-3-methylaspartate as products. MAL is of considerable biocatalytic interest because of its potential use for the asymmetric synthesis of substituted aspartic acids, which are important building blocks for synthetic enzymes, peptides, chemicals, and pharmaceuticals. Here, we have cloned the gene encoding MAL from the thermophilic bacterium Carboxydothermus hydrogenoformans Z-2901. The enzyme (named Ch-MAL) was overproduced in Escherichia coli and purified to homogeneity by immobilized metal affinity chromatography. Ch-MAL is a dimer in solution, consisting of two identical subunits (∼49 kDa each), and requires Mg(2+) and K(+) ions for maximum activity. The optimum pH and temperature for the deamination of (2S,3S)-3-methylaspartic acid are 9.0 and 70°C (k (cat) = 78 s(-1) and K (m) = 16 mM). Heat inactivation assays showed that Ch-MAL is stable at 50°C for >4 h, which is the highest thermal stability observed among known MALs. Ch-MAL accepts fumarate, mesaconate, ethylfumarate, and propylfumarate as substrates in the ammonia addition reaction. The enzyme also processes methylamine, ethylamine, hydrazine, hydroxylamine, and methoxylamine as nucleophiles that can replace ammonia in the addition to mesaconate, resulting in the corresponding N-substituted methylaspartic acids with excellent diastereomeric excess (>98% de). This newly identified thermostable MAL appears to be a potentially attractive biocatalyst for the stereoselective synthesis of aspartic acid derivatives on large (industrial) scale.
Tags
IRIS
•
Ammonia
Literature Search – March 2012 (private)
Literature Search Results
Home
Learn about HERO
Using HERO
Search HERO
Projects in HERO
Risk Assessment
Transparency & Integrity