Designed specifically on shape nothing will fit the

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Designed specifically on shape Nothing will fit the shape of the enzyme unless it has the same shape of the enzyme Naming enzymes The first enzyme discovered were given arbitrary names. An international committee later decided to end all enzymes with the suffix –ase. They also decided to make the first part of the name apply to the function of the enzyme o Phosphatases = remove phosphate groups o Synthetases = catalyze dehydration synthesis Enzyme activity Measured by the rate at which substrate is converted to product Influenced by o Concentration of enzyme and substrate o Enzyme-substrate affinity = do they stick to each other very well or just a little bit o Temperature o pH o Regulation by modulators (allosteric regulation) = groups that can be added to them
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15 o Covalent regulation (regulation by chemical groups) o Feedback inhibition = multistep pathways o Feed-forward activation Regulation of enzymatic reaction rates How substrate and enzyme concentrations affect reaction rates o A lot of enzyme v very little enzyme o At a certain point, you will reach a maximum o The rate will increase as the substrate concentration increases but eventually all the substrates will be found by all the enzymes or all the enzymes are working How substrate-enzyme affinity affects reaction rate o Take one enzyme with very high affinity (green) and one with a very low affinity (blue) o Find that if you add enough substrate, it doesn’t matter because you will get the same result o But if you have to compete, the substrate with the higher affinity will have a faster reaction rate o Affinity matter a lot at low substrate concentrations; at high substrate concentrations, the reactions will be the same Temperature o An increase in temperature will increase the rate of reactions until the temperature reaches a few degrees above body temperature. At this point, the enzyme is denatured (can be caused by fever) pH o Enzymes exhibit peak activity within a narrow pH range = optimum pH Due to changes in enzyme conformation Optimum pH typically reflects the pH of the fluid the enzyme is found in Stomach vs. saliva Covalent regulation o A molecule attaches to this enzyme with a covalent bond o Generally another enzyme that does this; enzymes are normally regulated by other enzymes Phosphorylation v. Dephosphorylation o Protein kinase = enzyme that does all the exact same thing; all kinase phosphorylates > adds a phosphate group to another protein o Phosphatase = removes the phosphate group or dephosphorylates o Phosphorylation = makes a protein active o Dephosphorylation = turns a protein off; makes it inactive Metabolic Pathways o Most reactions are linked together in a chain (or web) called a metabolic pathway These begin with an initial substrate and end with a final product, with many enzymatic steps along the way
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16 o Provides a lot of opportunity for you to control the rate of reaction
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