Biodehalogenation: reactions of cytochrome P-450 with polyhalomethanes

Abstract

The products, stoichiometry, and kinetics of the oxidation of the enzyme cytochrome P-450 cam by five polyhalomethanes and chloronitromethane are described. The reactivity of the enzyme is compared with that of deuteroheme and with the enzyme in its native cell, Pseudomonas putida (PpG-786). In all cases, the reaction entails hydrogenolysis of the carbon-halogen bond: 2FeIIP + RCXn----2FeIIIP + RCHXn-1 (P = porphyrin or P-450 cam in vitro and in vivo). Trichloronitromethane was the fastest reacting substrate, and chloroform was the slowest. The results establish that P. putida is a valid whole cell model for the reductase activity of the P-450 complement in these reactions. The reactions of cytochrome P-450 with polyhaloalkanes proceed in a manner quite analogous to other iron(II) proteins in the G conformation. The chemistry observed for the enzyme parallels that of its iron(II) porphyrin active site. Iron-bonded carbenes are not intermediates, and hydrolytically stable iron alkyls are not products of these reactions.

Transformation of tetra- and trichloromethane to CO2 by anaerobic bacteria is a non-enzymic process

“…unpublished). Four metallo-prophyrincontaining systems have been demonstrated to dehaiogenate CC14: cytochrome P450 [16], reduced iron (II) porphyrin [17], vitamin B12 [11,18] and coenzyme F430 [19]. All of these require reduced conditions.…”

Anaerobic dechlorination of tetrachloromethane and 1,2-dichloroethane to degradable products by pure cultures of Desulfobacterium sp. and Methanobacterium sp.

“…A few of these compounds, generally with a low level of chlorination, are subject to aerobic degradation [ [2][3][4][5][6][7] or transformation [8-10; see also 11], and some of these degradative capacities can be applied to waste or water treatment [5,12,13]. But for the most part, the highly chlorinated solvents are subject only to anaerobic transformation [14][15][16][17][18][19][20][21][22].…”

Microbial degradation of pesticide: A review

“…The biochemical reactions for degradation are achieved through a number of different enzymes such as dehydrogenases (Bourquin, 1977;Singh and Singh, 2005), cytochrome p450 (Castro et al, 1985;Jauregui et al, 2003), dioxigenases (Nadeau et al, 1994;Van Eerd et al, 2003), ligninases (Pizzul et al, 2009). Several reports have documented the capability of different genera of fungi to degrade organochlorines.…”