A haloalkane dehalogenase

Bosma T, J Damborsky, G Stucki, DB Janssen (2002) Biodegradation of 1,2,3-trichloropropane through directed evolution and heterologous expression of a haloalkane dehalogenase gene. Appl Environ Microbiol 68 3582-3587. 

Hur S, Kahn K, Bruice TC (2003) Comparison of Formation of Reactive Conformers for the SN2 Displacements by CH3C02 in Water and by Aspl24-C02" in a Haloalkane Dehalogenase. Proc Natl Acad Sci U S A 100 2215... 

Nagata, Y., K. Miyauchi, J. Damborsky, K. Manova, A. Ansorgova, and M. Takagi. 1997. Purification and characterization of a haloalkane dehalogenase of a new substrate class from a y-hexachlorocyclohexane-degrading bacterium, Sphin-gomonas paucimobilis UT26. Appl. Environ. Microbiol. 63 3703-3710. 

Edmond Y. Lau, Kalju Kahn, Paul A. Bash and Thomas C. Bruice, The importance of reactant positioning in enzyme catalysis a hybrid quantum mechanics/molecular mechanics study of a haloalkane dehalogenase, Proceedings of the National Academy of Sciences USA, 97 (2000), 9937-9942. 

Nucleophilic substitution is one of a variety of mechanisms by which living systems detoxify halogenated organic compounds introduced into the environment Enzymes that catalyze these reactions are known as haloalkane dehalogenases The hydrolysis of 1 2 dichloroethane to 2 chloroethanol for example is a biological nude ophilic substitution catalyzed by a dehalogenase... 

Jesenska A, M Bartos, V Czernekova, I Rychh k, I Pavlik, J Damborsky (2002) Cloning and expression of the haloalkane dehalogenase gene dhmA from Mycobacterium avium N85 and preliminary characterization of DhmA. Appl Environ Microbiol 68 3224-3230. 

Jesenska A, M Pavlova, M Strouhal, R Chaloupkova, I Tesmska, M Monincova, Z Prokop, M Bartos, 1 Pavlik, 1 Rychllk, P Mdbius, Y Nagata, J Damborsky (2005) Cloning, biochemical properties, and distribution of mycobacterial haloalkane dehalogenases. Appl Environ Microbiol 71 6736-6745. 

Nagata Y, Z Prokop, Y Sato, P Jerabek, A Kumar, Y Ohtsubo, M Tsuda, J Damborsky (2005) Degradation of b-hexachlorocyclohexane by haloalkane dehalogenase LinB from Sphingomonas paucimobilis UT 26. Appl Environ Microbiol 71 2183-2185. 

Lewandowicz A, J Rudzinski, L Tronstad, M Widersten, P Ryberg, O Matsson, P Paneth (2001) Chlorine isotope effects on the haloalkane dehalogenase reaction. J Am Chem Soc 123 4550-4555. 

The haloalkane dehalogenase DhlA mechanism takes place in two consecutive Sn2 steps. In the first, the carboxylate moiety of the aspartate Aspl24, acting as a nucleophile on the carbon atom of DCE, displaces chloride anion which leads to formation of the enzyme-substrate intermediate (Equation 11.86). That intermediate is hydrolyzed by water in the subsequent step. The experimentally determined chlorine kinetic isotope effect for 1-chlorobutane, the slow substrate, is k(35Cl)/k(37Cl) = 1.0066 0.0004 and should correspond to the intrinsic isotope effect for the dehalogenation step. While the reported experimental value for DCE hydrolysis is smaller, it becomes practically the same when corrected for the intramolecular chlorine kinetic isotope effect (a consequence of the two identical chlorine labels in DCE). 

Amino acid sequence relationships have suggested a number of HYL families based on percent identity, enzymes with >40% identity belonging to the same family [48]. Families so identified include the mammalian microsomal EH (HYL1), the mammalian cytosolic EH (HYL2), the plant cytosolic EH (HYL3), and bacterial C-X bond hydrolases (haloacid dehydrogenases, HAD, and haloalkane dehalogenases, HLD). 

J. P. Schanstra, D. B. Janssen, Kinetics of Halide Release of Haloalkane Dehalogenase Evidence for a Slow Conformational Change , Biochemistry 1996, 35, 5624 - 5632 J. 

Increase in water activity has an opposite effects on activity and stability of whole cells. Both for R. eiythropolis and X. autotrophicus an increase in dehalogenation was noticed on raising water activity [14, 15]. Interestingly, a minimum water activity of 0.4 was required in both cases to observe hydrolysis of 1-chlorobutane, while Dravis et al. [47] showed that the isolated haloalkane dehalogenase of R. 

Figure 12-1 The active site structure of haloalkane dehalogenase from Xanthobacter autotrophicus with a molecule of bound dichloroethane. See Pries et al.13 The arrows illustrate the initial nucleophilic displacement. The D260 - H289 pair is essential for the subsequent hydrolysis of the intermediate ester formed in the initial step.

Lewandowicz A, Rudzinski J, Tronstad L, Widersten M, Ryberg P, Matsson O, Paneth P (2001) Chlorine Kinetic Isotope Effects on the Haloalkane Dehalogenase Reaction. J Am Chem Soc 123 4550... 

Damborsky, J., Rome, E., Jesenska, A., Nagata, Y., Klopman, G., Peijnenburg, W.J.G.M. (2001) Structure-specificity relationships for haloalkane, dehalogenases. Environ. Toxicol. Chem. 20, 2681-2689. 

It is well established that the same three-dimensional scaffolding in proteins often carries constellations of amino acids with diverse enzymatic functions. A classic example is the large family of a/jS, or TIM, barrel enzymes (Farber and Petsko, 1990 Lesk et ai, 1989). It appears that lipases are no exception to date five other hydrolases with similar overall tertiary folds have been identified. They are AChE from Torpedo calif arnica (Sussman et al., 1991) dienelactone hydrolase, a thiol hydrolase, from Pseudomonas sp. B13 (Pathak and Ollis, 1990 Pathak et al, 1991) haloalkane dehalogenase, with a hitherto unknown catalytic mechanism, from Xanthobacter autotrophicus (Franken et al, 1991) wheat serine carboxypeptidase II (Liao et al, 1992) and a cutinase from Fusa-rium solani (Martinez et al, 1992). Table I gives some selected physical and crystallographic data for these proteins. They all share a similar overall topology, described by Ollis et al (1992) as the a/jS hydrolase... 

Fig. 13. The alp hydrolase fold and it variations. (A) cudnase, (B) dienelactone hydrolase and haloalkane dehalogenase, (C) wheat carboxypepddase, (D) RmL, (E) hPL, (F) GcL and AChE the three catalytic residues, always in the order Ser, Asp/Glu, and His, appear as dark dots. The folds are aligned in such a way as to show the structural homologies within the hydrolytic domains, somewhat divorced from the N-terminal part of the sheet. The hPL is a two-domain protein, and the location of the additional C-terminal domain is indicated.

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