Enzyme/ja: Difference between revisions

Like all catalysts, enzymes increase the [[reaction rate]] by lowering its [[activation energy]]. Some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is [[orotidine 5'-phosphate decarboxylase]], which allows a reaction that would otherwise take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, nor do they alter the [[Chemical equilibrium|equilibrium]] of a reaction. Enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: [[Enzyme inhibitor|inhibitors]] are molecules that decrease enzyme activity, and [[enzyme activator|activators]] are molecules that increase activity. Many therapeutic [[drug]]s and [[poison]]s are enzyme inhibitors. An enzyme's activity decreases markedly outside its optimal [[temperature]] and [[pH]], and many enzymes are (permanently) [[Denaturation (biochemistry)|denatured]] when exposed to excessive heat, losing their structure and catalytic properties.