100s to 1000s of chemical rxn in human body • Enzymes speed up rxn by millions and even billions of times • Single enzyme molec. acts on about 1000 substrate molecules/second.
IMPORTANCE OF ENZYMES • Enzymes are biological catalyststhat speed up chemical reactions by: • Lower the amount of energy needed for rxn • Not changed by rxn • Not used up by rxn
Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reactants Reaction pathway with enzyme Products They lower the amount of energy needed for a reaction.
Responsible for metabolism: • Catabolism: breaking apart molecules (hydrolysis) • Anabolism: building molecules (dehydration synthesis/condensation rxn)
Lipase-lipids Protease-proteins Sucrase-sucrose Most enzymes are named after the substrate they work on (usually ending in “-ase”).
Coenzymes • Another chemical (non-protein) that helps enzymes do work. • Example vitamins
Substrate • Reactants that enzymes work on. • Can be a big molec that needs broken down or small molec that need to be joined together.
Product • The altered substrate produced at the end of the reaction.
Active Site • The place on the enzyme where the substrate and enzyme interact. • The substrate fits like a key in the “lock” of the active site.
Enzyme Specificity • Enzymes are very specific about which types of substrates they can work on. • B/C of this, a different enzyme is needed for almost every rxn in the body.
Denaturation • An enzyme’s active site changes shape, which can stop or slow down biological activity, usually permanent • Causes: • Temperature change • pH change
pH • There is a range of tolerance specific to each enzyme
Temperature • There is a range of tolerance specific to each enzyme
Inhibitors • Substances that interfere with the action of the enzyme. • 2 types • Competitive • Noncompetitive • Ex. Toxins, poisons, antibiotics
Competitive Inhibitors • Are able to bind at the active site and block the way for the substrate.
Noncompetitive Inhibitors • Bind someplace other than the active site causing a change in the active site. • Substrate can no longer bind.