title: Lysine-ketoglutarate reductase in human tissues.
abstract: Lysine-ketoglutarate reductase (saccharopine dehydrogenase (NADP+, lysine-forming) EC 1.5.1.8) from human liver has been partially purified and characterized. A spectrophotometric assay is described. The Michaelis constants have been determined for lysine (1.5-10-3 M), alpha-ketoglutarate (1-10-3 M) and NADPH (8-10-5 M). The pH optimum is 7.8. The enzyme is product inhibited. The specificity of the enzyme, response to inhibitors, pH and thermal stability are reported. Lysine-ketoglutarate reductase is present in high concentration in liver and heart, to a lesser degree in kidney and skin and in trace amounts in several other tissues. Saccharopine dehydrogenase (saccharopine dehydrogenase (NAD+, L-glutamate-forming) EC 1.5.1.9) was demonstrable only in liver and kidney. Lysine-ketoglutarate reductase reacts effectively with delta-hydroxylysine.
mesh_terms: D006801:Humans; D006863:Hydrogen-Ion Concentration; D007656:Ketoglutaric Acids; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008239:Lysine; D009206:Myocardium / Q000201:enzymology; D009249:NADP; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D012867:Skin / Q000201:enzymology; D013053:Spectrophotometry; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013696:Temperature
chemical_list: D007656:Ketoglutaric Acids; D013438:Sulfhydryl Compounds; D009249:NADP; D000587:Oxidoreductases Acting on CH-NH Group Donors; D008239:Lysine