1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ - - 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ bifunctional enzyme showing aspartate kinase, 2.7.2.4, and homoserine dehydrogenase activities 657018 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ bifunctional enzyme showing aspartate kinase, EC 2.7.2.4, and homoserine dehydrogenase activities 642340, 642341, 654640 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ L-homoserine oxidation by StHSD proceeds through a sequentially ordered mechanism in which NAD+ binds to the free form of the enzyme, after which L-homoserine binds to the enzyme-NAD+ complex -, 762453 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ ordered bi bi kinetic mechanism in which nicotinamide cofactor binds first and leaves last in the reaction sequence 712490 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ proposed reaction mechanisms of hydride transfer from L-homoserine in the active site of Paracoccidioides brasiliensis homoserine dehydrogenase (HSD), Glu218 accepts a proton from the hydroxyl group of L-homoserine, which donates a hydride to the nC-4 carbon of NAD+. Lys233, Lys122, and the water molecule at position 374 (Wat374) serve to bind the substrate -, 760354 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ role of conserved water molecules and a lysine residue in hydride transfer between the substrate and the cofactor. Lys105, which is located at the interface of the catalytic and cofactor-binding sites, mediates the hydride transfer step of the reaction mechanism of the enzyme. Potential reaction mechanisms for homoserine dehydrogenase, overview -, 739791 1.1.1.3 L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ two possible catalytic mechanisms of homoserine oxidation. (a) Lys99 is the acidx02base catalytic residue. The hydroxy group of L-Hse is activated by protonated Lys195, and a proton from the Od of L-Hse is captured by the deprotonated Lys99. Lys99 exists in the simple proton pathway, in which a proton can go in and out of an active site easily. (b) Lys195 is drown as an acidx02base catalytic residue. L-Hse and Asp191 exist deep inside of the active site and have no interaction to the surface. Thus, the direct proton pathway from Lys195 to the bulk water region cannot be realized. Lys99 and Lys195 of TtHSD are essential for catalysis 761404