Pyrroline-5-carboxylate reductase

FIG. 5.1 Proline metabolism. 1, Proline oxidase 2, A -pyrroline-5-carboxylate reductase 3, spontaneous reaction 4, A -pyrroline-5-carboxylate dehydrogenase 5, glutamate dehydrogenase 6, see Fig. 5.2. 

Noguchi, M., A. Koiwai, and E. Tamaki Studies on nitrogen metabolism in tobacco plants. Part VII. 5-Pyrroline-5-carboxylate reductase from tobacco leaves Agr. Biol. Chem. (Tokyo) 30 (1966) 452-456. 

Vansuyt, G., J.C. Vallee, and J. Prevost Pyrroline-5-carboxylate reductase and prohne dehydrogenase in Nicotiana tabacum var. Xanthi NC as a function of its development Physiol. Veg. 17 (1979) 95-105. 

The potential of biotransformations with genetically modified microorganisms can be illustrated by the following example, where the chain of added-value to amino acid products is also recognisable The Mercian Company (Japan) uses a recombinant E. coli strain to prepare (S)-piperidine-2-car-boxylic acid from (L)-lysine. In this strain, the (L)-lysine-permease transport system is overexpressed, so that in this pathway lysine is produced efficiently in the cells. The bacteria possess additionally a (L)-lysine-aminotransferase from Flavobacterium lutescens, which brings about the deamination of lysine. The thus generated aldehyde is in equilibrium with its intramolecular imine, which, in presence of the E. co/i-specific pyrroline-5-carboxylate reductase, is reduced with NADPH to (S)-piperidine-2-carboxylic acid. The turnover... 

A -Pyrroline-5-carboxylate reductase catalyzes the reduction of this compound to proline. In the rat liver enzyme DPNH and, less effectively, TPNH serve as hydrogen donors 115,120,123). In the Neurospora enzyme TPNH is sixteen times as effective as DPNH 124). A -Pyrroline-S-car-boxylate reductase has been observed in various mammalian tissues 120, 123) and in a variety of microorganisms 116, 123-126). The enzyme has been purified about thirtyfold, from Neurospora 126) and about eightyfold in the writer s laboratory from animal tissue 126). The enzyme is active on a number of A -pyrroline derivatives. The optimum activity of the liver and Neurospora enzymes is at about pH 7.0. The reductase is an SH enzyme and it is strongly inhibited by the usual SH reagents. Estimation of the kinetic constants of the liver enzyme yielded X values of 2.0 X 11" M for pyrroline-5-carboi late and 2.5 X 10 M for DPNH. 

Samuels, S.E., K.S. Acton, and R.O. Ball, 1989. Pyrroline-5-carboxylate reductase and proline oxidase activity in the neonatal pig. J. Nutr. 119, 1999-2004. 

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