Mechanism and Activity
The active site of malate dehydrogenase is a hydrophobic cavity within the protein complex that has specific binding sites for the substrate and its coenzyme, NAD+. In its active state, MDH undergoes a conformational change that encloses the substrate to minimize solvent exposure and to position key residues in closer proximity to the substrate. The three residues in particular that comprise a catalytic triad are histidine (His-195), aspartate (Asp-168), both of which work together as a proton transfer system, and arginines (Arg-102, Arg-109, Arg-171), which secure the substrate. Kinetic studies show that MDH enzymatic activity is ordered. NAD+/NADH is bound before the substrate.
Note: the structure of malate in the figure above is not correct. Malate should have four carbons, not six as the figure implies.
Read more about this topic: Malate Dehydrogenase
Famous quotes containing the words mechanism and/or activity:
“The two elements the traveler first captures in the big city are extrahuman architecture and furious rhythm. Geometry and anguish. At first glance, the rhythm may be confused with gaiety, but when you look more closely at the mechanism of social life and the painful slavery of both men and machines, you see that it is nothing but a kind of typical, empty anguish that makes even crime and gangs forgivable means of escape.”
—Federico García Lorca (1898–1936)
“I suspect there isn’t an actor alive who was able to truthfully answer his family’s questions after his first day’s activity in his future profession.”
—Simone Signoret (1921–1985)