title: Kinetic and sequence-structure-function analysis of known LinA variants with different hexachlorocyclohexane isomers.
abstract: BACKGROUND
  Here we report specific activities of all seven naturally occurring LinA variants towards three different isomers, α, γ and δ, of a priority persistent pollutant, hexachlorocyclohexane (HCH). Sequence-structure-function differences contributing to the differences in their stereospecificity for α-, γ-, and δ-HCH and enantiospecificity for (+)- and (-)-α -HCH are also discussed.
  
  
  RESULTS
  Enzyme kinetic studies were performed with purified LinA variants. Models of LinA2(B90A) A110T, A111C, A110T/A111C and LinA1(B90A) were constructed using the FoldX computer algorithm. Turnover rates (min(-1)) showed that the LinAs exhibited differential substrate affinity amongst the four HCH isomers tested. α-HCH was found to be the most preferred substrate by all LinA's, followed by the γ and then δ isomer.
  
  
  CONCLUSIONS
  The kinetic observations suggest that LinA-γ1-7 is the best variant for developing an enzyme-based bioremediation technology for HCH. The majority of the sequence variation in the various linA genes that have been isolated is not neutral, but alters the enantio- and stereoselectivity of the encoded proteins.
authors.affiliation: Department of Zoology, University of Delhi, Delhi, India.
authors.forename: Pooja
authors.initials: P
authors.lastname: Sharma
authors.forename: Rinku
authors.initials: R
authors.lastname: Pandey
authors.forename: Kirti
authors.initials: K
authors.lastname: Kumari
authors.forename: Gunjan
authors.initials: G
authors.lastname: Pandey
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Jackson
authors.forename: Robyn J
authors.initials: RJ
authors.lastname: Russell
authors.forename: John G
authors.initials: JG
authors.lastname: Oakeshott
authors.forename: Rup
authors.initials: R
authors.lastname: Lal
mesh_terms: D000927:Anticonvulsants / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004926:Escherichia coli / Q000201:enzymology; D014644:Genetic Variation / Q000235:genetics*; D001556:Hexachlorocyclohexane / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D008956:Models, Chemical; D013237:Stereoisomerism
chemical_list: D000927:Anticonvulsants; D001426:Bacterial Proteins; D001556:Hexachlorocyclohexane; D008190:Lyases