Enzyme Structure & Function Different Types of Catalytic Strategies: Acid/Base Catalysis: when an enzyme acts as either an acid or a base (helps with proton transfer) Covalent Catalysis: when an enzymes help form a covalent bond with another molecule (helps with electron transfer) Electrostatic Catalysis: when an enzyme uses its charge in order to stabilize a molecule (Mg2+ as a cofactor could be used to stabilized a negatively charged molecule of DNA) Proximity/Orientation Catalysis: allows molecules to collide at the most optimal orientation Use Reaction Coordinate Diagram in order to see the differences in activation energy and overall energies of products vs. reactants (lower energy state = more stable | higher energy state = less stable) Transition State: the highest energy state between the conversion of reactants to products Enzymes speed up a reaction by lowering the Activation Energy Free energy of the reactants and products DO NOT change with the addition of an enzyme/catalyst ONLY the activation energy will change Finally, remember the enzyme/catalyst is NOT used up in a reaction Induced Fit Model: enzyme-substrate interaction is not like a puzzle piece (Lock & Key Model) and act more like two pieces of clay that end up molding together (substrate causes the active site to more closely resemble its own shape) When ES is in the induced fit portion (transition state) the enzyme is in its highest energy state (interaction between the enzyme and substrate is the highest here) - AKA binding is STRONGEST at the TRANSITION STATE Enzymes CAN and will typically bind more than one substrate Allosteric Site: any binding site other than the enzyme’s active site 6 Main Types of Enzymes: 1. Transferase: moves a functional groups from one molecule to another 2. Ligase: combines two molecules together 3. Oxidoreductase: transfer of electrons from one molecule to another (hence oxidation or reduction) - can catalyze either direction normally a. Dehydrogenase: a type of oxidoreductase that is the transfer of electors (removal of a hydride functional group) 4. Isomerase: involved in converting a molecule into one of its isomers 5. Hydrolase: use water to cleave a molecule into two 6. Lyase: cleave a molecule into two WITHOUT using water by generating either a double bond between two atoms or a ring structure in order to work Coenzyme: are organic carrier molecules (carbon based) and are only really ever involved in transferring things from one molecule to another Cofactor: directly participate in the catalytic activity of an enzyme (i.e. stabilize substrate/enzyme, etc.) Vitamins and minerals are things our body can’t make from scratch and are also examples of coenzymes and cofactors Vitamins are carbon based cofactors/coenzymes while Minerals are inorganic cofactors Enzymes are specific for different pH’s (can change the protonation of certain amino acids and its interaction with other amino acids and cofactors) and temperatures (denatures the protein and inactivate it)