Overexpression and characterisation of non-stereospecific haloacid Dehalogenase E (DehE) of Rhizobium sp.
Fahrul Z. Huyop1*, Tan Yea Yusn1, Marcella Ismail1, Roswanira Ab Wahab2 and Ronald A. Cooper3
1Biology Department, University Technology Malaysia, 81310 Skudai, Johor, Malaysia
2Chemistry Department, University Technology Malaysia, 81310 Skudai, Johor, Malaysia
3Biochemistry Department, University of Leicester, United Kingdom
*Author for Correspondence.
Biology Department, University Technology Malaysia, 81310 Skudai, Johor, Malaysia.
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Key words: dehalogenase, DehL, DehE, DehD, Rhizobium sp.
Abstract.
The Rhizobium sp. dehalogenase enzyme (DehE) produced by heterologous expression of the cloned gene in E.coli was purified and characterised. The Km, Kcat and the Specificity Constants were determined. The enzyme shows nonstereospecific and could act on D- and L- isomer of 2-chloropropionate. The derived amino acid sequence of DehE showed little identity to Pseudomonas putida 113 DL-DEX (39% homology) but there was significant identity to two other dehalogenases (DehI and DhlIV) – 72% homology, that act non-selectively on 2-chloropropionate. The amino acid sequence of dehE contains 4 cysteine residues but their involvement in the mechanism of catalysis is still unclear based on their end product configuration. The Km, Kcat and Specificity Constants values for brominated compound suggested that this compound is a better substrate for growth and for the DehE enzyme.
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