Phenylphosphate carboxylase

Primary structure analysis of phenylphosphate carboxylase of T. aromatica is performed in detail, to clarify the reaction mechanism involving four kinds of subunits. The a, (3, y, 8 subunits have molecular masses of 54, 53, 18, and lOkDa, respectively, which make up the active phenylphosphate carboxylase. The primary structures of a and (3 subunits show homology with 3-octaprenyl-4-hydroxybenzoate decarboxylase, 4-hydroxybenzoate decarboxylase, and vanil-late decarboxylase, whereas y subunit is unique and not characterized. The 18kDa 8 subunit belongs to a hydratase/phosphatase protein family. Taking 4-hydroxybenzoate decarboxylase into consideration, Schiihle and Fuchs postulate that the a(3y core enzyme catalyzes the reversible carboxylation.  

The enzymes catalyzing the Kolbe-Schmitt carboxylation seem to occur ubiquitously. Some of them, such as 2,6-dihydroxybenzoate decarboxylase and pyrrole-2-carboxylate decarboxylase, catalyze efficiently the reverse carboxylation reaction and accumulate high concentration of 2,6-dihydroxybenzoate from 1,3-dihydroxybenzene and pyrrole-2-carboxylate from pyrrole, respectively, in the 

Sharak-Genthner, B. R. Townsend, G. T. Chapman, P. J. EEMS Microbiol. Lett. 1991, 78, 265-270. 

The Electronic Theory of Organic Chemistry, Oxford University Press London 1949, pp. 1-324. 

Matsui, T. Yoshida, T. Yoshunura, T. Nagasawa, T. Appl. Microbiol. Biotechnol. 2006, 73, 95-102. 

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Schiihle K, G Fuchs (2004) Phenylphosphate carboxylase a new C-C lyase involved in anaerobic phenol metabolism in Thauera aromatica. J Bacterial 186 4556-4567. 

Attempts to enhance the low stability by supporting the enzyme on low melting agar has been carried out successfully [51]. Supercritical carbon dioxide was also used as solvent/reagent for semi-purified phenylphosphate carboxylase extracted from T. aromatica [52]. 

Phenylphosphate carboxylase can also carboxylate catechol and o-cresol as it can phenol [53] to yield 3,4-dihydroxybenzoate and 4-hydroxy-3-methylbenzoate respectively. Similarly, Sedimentibacter hydroxybenzoicus, which catalyzes the... 

Aresta M, Tommasi L Dileo C, Dibenedetto A, Narracci M (2001) Biotechnological synthesis of 4-OH benzoate mediated by a phenylphosphate-carboxylase enzyme 221st National Meeting, American Chemical Society, San Diego, CA, April 1-5, Inorganic division. Abstract tT 581... 

Dibenedetto A, Lo Noce R, Pastore C, Aresta M, Fragale C (2006) First in vitro use of the phenylphosphate carboxylase enzyme in supercritical CO2 for the selective carboxylation of phenol to 4-hydroxybenzoic acid. Environ Qiem Lett 3 145-148... 

As noted previously, the use of supercritical CO allows decarboxylases to catalyze the reverse carboligation reaction because the solvent is also the reactant and thus present at a very high concentration. In one example, Thauera aromatica phenylphosphate carboxylase was used to carboxylate phenylphosphate in the para-position without any detectable ortho-product in supercritical CO without any added H O (Figure 3.18) [28]. 

Carboxylation in supercritical CO without H O by T. aromatica phenylphosphate carboxylase [28]. 

Lack, A. and G. Fuchs. 1992. Carboxylation of phenylphosphate by phenol carboxylase, an enzyme system of anaerobic phenol metabolism. J. Bacteriol. 174 3629-3636. 

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