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- Title
Important amino acid residues of hexachlorocyclohexane dehydrochlorinases (LinA) for enantioselective transformation of hexachlorocyclohexane isomers.
- Authors
Shrivastava, Nidhi; Macwan, Ankit; Kohler, Hans-Peter; Kumar, Ashwani
- Abstract
LinA-type1 and LinA-type2 are two well-characterized variants of the enzyme 'hexachlorocyclohexane (HCH)-dehydrochlorinase'. They differ from each other at ten amino acid positions and exhibit differing enantioselectivity for the transformation of the (-) and (+) enantiomers of α-HCH. Amino acids responsible for this enantioselectivity, however, are not known. An in silico docking analysis identified four amino acids (K20, L96, A131, and T133) in LinA-type1 that could be involved in selective binding of the substrates. Experimental studies with constructed mutant enzymes revealed that a combined presence of three amino acid changes in LinA-type1, i.e. K20Q, L96C, and A131G, caused a reversal in its preference from the (-) to the (+) enantiomer of α-HCH. This preference was enhanced by the additional amino acid change T133 M. Presence of these four changes also caused the reversal of enantioselectivity of LinA-type1 for δ-HCH, and β-, γ-, and δ-pentachlorocyclohexens. Thus, the residues K20, L96, A131, and T133 in LinA-type1 and the residues Q20, C96, G131, and M133 in LinA-type 2 appear to be important determinants for the enantioselectivity of LinA enzymes.
- Subjects
AMINO acid residues; HEXACHLOROCYCLOHEXANES; ENANTIOMERS; MOLECULAR docking; BIOCHEMICAL substrates
- Publication
Biodegradation, 2017, Vol 28, Issue 2/3, p171
- ISSN
0923-9820
- Publication type
Article
- DOI
10.1007/s10532-017-9786-9