Accepted name: D-proline reductase
Reaction: 5-aminopentanoate + a [PrdC protein with a selenide-sulfide bridge] = D-proline + a [PrdC protein with thiol/selenol residues]
Other name(s): prdAB (gene names); D-proline reductase (dithiol)
Systematic name: 5-aminopentanoate:[PrdC protein] oxidoreductase (cyclizing)
Comments: A pyruvoyl- and L-selenocysteine-containing enzyme found in a number of Clostridial species. The pyruvoyl group, located on the PrdA subunit, binds the substrate, while the selenocysteine residue, located on the PrdB subunit, attacks the α-C-atom of D-proline, leading to a reductive cleavage of the C-N-bond of the pyrrolidine ring and formation of a selenoether. The selenoether is cleaved by a cysteine residue of PrdB, resulting in a mixed selenide-sulfide bridge, which is restored to its reduced state by another selenocysteine protein, PrdC. 5-aminopentanoate is released from PrdA by hydrolysis, regenerating the pyruvoyl moiety. The resulting mixed selenide-sulfide bridge in PrdC is reduced by NADH.
1.  Stadtman, T.C. and Elliott, P. Studies on the enzymic reduction of amino acids. II. Purification and properties of a D-proline reductase and a proline racemase from Clostridium sticklandii. J. Biol. Chem. 228 (1957) 983–997. [PMID: 13475375]
2.  Hodgins, D.S. and Abeles, R.H. Studies of the mechanism of action of D-proline reductase: the presence on covalently bound pyruvate and its role in the catalytic process. Arch. Biochem. Biophys. 130 (1969) 274–285. [PMID: 5778643]
3.  Kabisch, U.C., Gräntzdörffer, A., Schierhorn, A., Rücknagel, K.P, Andreesen, J.R. and Pich, A. Identification of D-proline reductase from Clostridium sticklandii as a selenoenzyme and indications for a catalytically active pyruvoyl group derived from a cysteine residue by cleavage of a proprotein. J. Biol. Chem. 274 (1999) 8445–8454. [PMID: 10085076]
4.  Bednarski, B., Andreesen, J.R. and Pich, A. In vitro processing of the proproteins GrdE of protein B of glycine reductase and PrdA of D-proline reductase from Clostridium sticklandii: formation of a pyruvoyl group from a cysteine residue. Eur. J. Biochem. 268 (2001) 3538–3544. [PMID: 11422384]
5.  Fonknechten, N., Chaussonnerie, S., Tricot, S., Lajus, A., Andreesen, J.R., Perchat, N., Pelletier, E., Gouyvenoux, M., Barbe, V., Salanoubat, M., Le Paslier, D., Weissenbach, J., Cohen, G.N. and Kreimeyer, A. Clostridium sticklandii, a specialist in amino acid degradation: revisiting its metabolism through its genome sequence. BMC Genomics 11:555 (2010). [PMID: 20937090]
[EC created 1972 as EC, modified 1982 (EC created 1961, incorporated 1982), transferred 2003 to EC, modified 2018]

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