S. Fetzner et F. Lingens, BACTERIAL DEHALOGENASES - BIOCHEMISTRY, GENETICS, AND BIOTECHNOLOGICAL APPLICATIONS, Microbiological reviews, 58(4), 1994, pp. 641-685
This review is a survey of bacterial dehalogenases that catalyze the c
leavage of halogen substituents from haloaromatics, haloalkanes, haloa
lcohols, and haloalkanoic acids. Concerning the enzymatic cleavage of
the carbon-halogen bond, seven mechanisms of dehalogenation are known,
namely, reductive, oxygenolytic, hydrolytic, and thiolytic dehalogena
tion; intramolecular nucleophilic displacement; dehydrohalogenation; a
nd hydration. Spontaneous dehalogenation reactions may occur as a resu
lt of chemical decomposition of unstable primary products of an unasso
ciated enzyme reaction, and fortuitous dehalogenation can result from
the action of broad-specificity enzymes converting halogenated analogs
of their natural substrate. Reductive dehalogenation either is cataly
zed by a specific dehalogenase or may be mediated by free or enzyme-bo
und transition metal cofactors, (porphyrins, corrins). Desulfomonile t
iedjei DCB-1 couples energy conservation to a reductive dechlorination
reaction. The biochemistry and genetics of oxygenolytic and hydrolyti
c haloaromatic dehalogenases are discussed. Concerning the haloalkanes
, oxygenases, glutathione S-transferases, halidohydrolases, and dehydr
ohalogenases are involved In the dehalogenation of different haloalkan
e compounds. The epoxide-forming halohydrin hydrogen halide lyases for
m a distinct class of dehalogenases. The dehalogenation of alpha-halos
ubstituted alkanoic acids is catalyzed by halidohydrolases, which, acc
ording to their substrate and inhibitor specificity and mode of produc
t formation are placed into distinct mechanistic groups. beta-Halosubs
tituted alkanoic acids are dehalogenated by halidohydrolases acting on
the coenzyme A ester of the beta-haloalkanoic acid. Microbial systems
offer a versatile potential for biotechnological applications. Becaus
e of their enantiomer selectivity, some dehalogenases are used as indu
strial biocatalysts for the synthesis of chiral compounds. The applica
tion of dehalogenases or bacterial strains in environmental protection
technologies is discussed in detail