# Enzymes --- An **enzyme** is a [[protein]][^1] that functions as a [[chemical reaction#Catalyst|catalyst]] in chemical reaction, speeding them up by bonding with and thus orienting different substrates in a better orientation. *Emzymes make life happen*. They are involved in *every* aspect of [[metabolism]], the [[cell cycle]], and survival in general. [^1]: Usually...see "rybozyemes" Our cyoplasm and our nucleus are *filled* with enzymes, and about 1/4 of our [[gene|genes]] code for enzymes. A **rybozyme** is a type of enzyme that is made out of RNA instead of proteins. ## Structure Enzymes tend to be globular proteins[^2] with a hydrophobic core, a hydrophilic exterior, and an accessable **catalytic**, or **active site**. The active site is the place on an enzyme that binds to a [[protein]] or some other substance during a reaction. [^2]: Again...usually. Again, see "rybozymes" [[cofactor#Coenzymes|Coenzymes]] are non-protein particles that help, or in some cases allow, the function of an enzyme. They may or may not be chemically bound to the enzyme for them to work. Enzymes are generally very very large compared to their substrates, which fit into little pockets. The fit between the enzyme and their substrate is critical and very precise. Some enzymes are made out of many subunits that fit together precisely. ![[enzyme and substrate.png]] ## Functions It's difficult to overstate their importance. **Enzymes do *all of the work* in biology**. They build up, [[digestive enzymes|break down]], and recycle. They bind *very* specifically to a *particular* substrate. When they are ready to do work, they have one structure. Once they bind to a substrate, and they go through a confirmational change, which can be very subtle, but effective. It either creates or breaks the chemical bonds of the substrate. Then, it releases the substrate and goes back to it's ready state. ### Lowering the Activation Energy Enzymes lower a reaction's activation energy, which means that all these reactions would occur normally, but now can proceed *considerably* faster than uncatalyzed reactions. ![[enzyme activation energy.png]] ## Constitutive & Inducible Enzymes **Constitutive enzymes** are produced just as a matter of course, whereas **inducible enzymes** are only produced under conditions where it would be helpful. ## Enzyme Regulation If enzymes were allowed to function unchecked, everything would get used up too fast, and thus enzymes need to be [[enzyme regulation|regulated]]. ## Enzyme Names Enzymes are described by their function, with the exception of a few arbitrarily named enzymes that were amung the first. They're not always a perfect 1:1 meaning, but the name often gives you a hint. For example: The suffix "-ase" added to a substance tells you the substrate that the enzyme modifies. ### Major Classes of Enzymes There are roughly six general classes of enzymes: **Oxidoreductases:** Performs [[redox]] reactions **Transferases:** Transfer [[functional group|functional groups]] **Hydrolases:** Catalyze [[hydrolysis and condensation reactions|hydrolysis]] **Lyases:** Cleave bonds in a way that's not hydrolosis or oxidation **Isomeraese:** [[isomer|isomerizes]] a molecule **Ligases:** Joins two molecules together **Kinases:** adds a [[phosphorylation|adds a phosphate]] ___