Ch. 5.3 - Enzymes

• energy required to kick-start a reaction - protects from cellular damage

• function as biological catalysts by lowering the energy of activation required to initiate the reaction • very selective -> 3D structure determines this specificity • function best under optimal temp and pH

specific substance on which an enzyme acts

• part of the enzyme where the substrate binds (often a pocket or groove) • R groups are important here

• enzymes aren’t consumed or permanently altered in the reactions • a single enzyme may act on thousands or millions of substrate per second • rate of enzymatic reactions is also dependent on the concentration of substrate available…up to the saturation point

• nonprotein molecules or ions that are required for proper functioning of the enzyme • enzymes require cofactors such as Zn, Fe, or Cu • bind to the active site and assist in the functioning of enzymes

• cofactor that is an organic molecule - ex: folic acid, riboflavin, niacin

• many are precursors to making coenzymes • substances that are necessary for life but that we have lost the ability to synthesize • vitamin deficiencies can lead to many disease states

cells control which reactions are occurring and how fast they’re occurring by switching genes on/off and by regulating the activity of them once they’re made

bind to the active site and “compete” with the substrate for the active site (like musical chairs with more people added)

• bind to the enzyme at another location-an allosteric site - changes the shape of the enzyme so the active site no longer fits the substrate

can damage the cell but can also be useful at times

• method of metabolic control in which the product of a metabolic pathway acts as an inhibitor of an enzyme in the pathway • products shuts off or slows the reaction that makes it, preventing the cell from wasting energy energy and making too much

• ibuprofen: inhibits the enzyme involved in the production of prostaglandins (increase the sensation of pain and cause swelling/inflammation) • penicillin: inhibits an enzyme that many bacteria use to make their cell walls • strong poisons: nerve gases, bind very strongly, often irreversibly, leading to paralysis of vital functions ad death • other: antidepressants, blood pressure meds, and a number of antibiotics

enzyme produced in an inactive form to protect the cells

• the digestive enzyme pepsin: wouldn’t want to digest our cells while the body wants to get it to the stomach where it needs to function • becomes active after reaching the acidic environment of stomach