1.5.1.1	evolution	enzyme Pyr2C reductase is a member of the ornithine cyclodeaminase/micro-crystallin superfamily, different from known dpkA protein, and there are several significant differences in the enzymatic properties between Azospirillum brasilense and another bacteria: substrate and coenzyme specificities, phylogenetic analysis	742531	
1.5.1.1	evolution	enzymes that reduce DELTA1-pyrroline-5-carboxylate and DELTA1-piperideine-6-carboxylate are aldimine reductases whereas enzymes that reduce DELTA1-piperideine-2-carboxylate and DELTA1-pyrroline-2-carboxylate (P2C/Pyr2C) are ketimine reductases (KRs)	743355	
1.5.1.1	malfunction	disruption of LhpI gene from Azospirillum brasilense leads to loss of growth on trans-3-hydroxy-L-proline (T3LHyp), D-proline and D-lysine	742531	
1.5.1.1	malfunction	disruption of LhpI gene from Azospirillum brasilense leads to loss of growth on trans-3-hydroxy-L-proline, D-proline and D-lysine, indicating that this gene has dual metabolic functions as a reductase for Pyr2C and DELTA1-piperidine-2-carboxylate in these pathways, and that the T3LHyp pathway is not linked to trans-4-hydroxy-L-proline and L-proline metabolism	742531	
1.5.1.1	metabolism	lysine degradation may be divided into two distinct pathways, namely (1) the pipecolate pathway which involves oxidation at the alpha-amino position followed by reduction of the product (P2C) to pipecolate by ketimine reductase (KR), and (2) the saccharopine pathway which involves oxidation at the epsilon-amino position The saccharopine pathway is predominantly mitochondrial, whereas the pipecolate pathway is predominantly cytosolic (but with a portion occurring in the peroxisomes). The DELTA1-piperideine-2-carboxylate (P2C) reductase enzyme activity is potently inhibited by thyroid hormones, thus suggesting a reciprocal relationship between enzyme catalysis and thyroid hormone bioavailability. KR is involved in a number of amino acid metabolic pathways. As DELTA1-piperideine-2-carboxylate (P2C) reductase it plays a role in the pipecolate pathway of lysine metabolism. Potent regulation of KR activity by thyroid hormones. KR is also involved in L-ornithine/L-glutamate/L-proline metabolism as well as sulfur-containing amino acid metabolism. Unique presence of the pipecolate pathway in brain. Cerebral pipecolate pathway, overview	743355	
1.5.1.1	metabolism	the enzyme is involved in the trans-3-hydroxy-L-proline pathway and the metabolic networks with D-lysine and D-proline, overview. The trans-3-hydroxy-L-proline pathway is not linked to trans-4-hydroxy-L-proline and L-proline metabolism	742531	
1.5.1.1	physiological function	enzyme AbLhpI is a bifunctional NAD(P)H-dependent Delta1-pyrroline-2-carboxylate/Delta1-piperideine-2-carboxylate reductase (Pyr2C/Pip2C reductase)	742531	
1.5.1.1	physiological function	identification of ketimine reductase (KR) as mu-crystalin (CRYM)/cytosolic thyroid hormone binding protein (THBP). CRYM is a major mammalian THBP, which has the ability to strongly bind thyroid hormones in an NADPH-dependent fashion. It is also active as a DELTA1-piperideine-2-carboxylate (P2C) reductase, which catalyzes the NAD(P)H-dependent reduction of -C=N- (imine) double bonds of a number of cyclic ketimine substrates including sulfur-containing cyclic ketimines. P2C exists in equilibrium with its open-chain form under acidic conditions, but at neutral pH, P2C exists predominantly as the enzymatically favorable cyclic ketimine form (in which the ring double bond is in the C=N form). P2C can also exist as an enamine, but only at basic pH values. The enzyme activity is potently inhibited by thyroid hormones, thus suggesting a reciprocal relationship between enzyme catalysis and thyroid hormone bioavailability. KR is involved in a number of amino acid metabolic pathways. As DELTA1-piperideine-2-carboxylate (P2C) reductase it plays a role in the pipecolate pathway of lysine metabolism. Potent regulation of KR activity by thyroid hormones. KR is also involved in L-ornithine/L-glutamate/L-proline metabolism as well as sulfur-containing amino acid metabolism. Although KR is important in the formation of L-pipecolate in the brain, it is also an important source of L-proline. This proline (via proline oxidase) in turn is an important source of DELTA1-pyrroline-5-carboxylate (Pyr5C) and hence of glutamate and to a lesser extent ornithine. Ketimine reductase is involved in several diseases	743355	
1.5.1.1	physiological function	the enzymatic reduction of Pyr2C to L-proline together with DAAO may be regarded as a salvage mechanism for converting D-proline, arising from the diet or intestinal bacteria, to L-proline, the more biological useful enantiomer in mammals	743353