Question: what is the substrate in the reaction above

title: Substrate (chemistry)
text: Although enzymes are typically highly specific , some are able to perform catalysis on more than one substrate , a property termed enzyme promiscuity . An enzyme may have many native substrates and broad specificity ( e.g. oxidation by cytochrome p450s ) or it may have a single native substrate with a set of similar non-native substrates that it can catalyse at some lower rate . The substrates that a given enzyme may react with in vitro , in a laboratory setting , may not necessarily reflect the physiological , endogenous substrates of the enzyme 's reactions in vivo . That is to say that enzymes do not necessarily perform all the reactions in the body that may be possible in the laboratory . For example , while fatty acid amide hydrolase ( FAAH ) can hydrolyze the endocannabinoids 2 - arachidonoylglycerol ( 2 - AG ) and anandamide at comparable rates in vitro , genetic or pharmacological disruption of FAAH elevates anandamide but not 2 - AG , suggesting that 2 - AG is not an endogenous , in vivo substrate for FAAH . In another example , the N - acyl taurines ( NATs ) are observed to increase dramatically in FAAH - disrupted animals , but are actually poor in vitro FAAH substrates .