enzymes Flashcards
enzymes
-proteins
-act as a framework in which reactions can take place
catalysts
-increase rates of chemical reactions
-not altered by the reactions
activation energy (Ea)
-the amount of energy required to start the reaction
transition state
activation energy puts the reactants in a reactive mode
transition state intermediates
activation energy changes the reactants into unstable forms with higher free energy
substrates
reactants
enzyme-substrate complex (ES)
held together by hydrogen bonds, electrical attraction, and covalent bonds
included fit
enzymes change shape when they bind the substrate, which alters the shape of the active site
enzyme activity can be controlled in two ways
-regulation of gene expression-how many enzyme molecules are made
-regulation of enzyme activity-enzyme may change shape, or be blocked by regulators
enzyme inhibitors
-molecules that bind to the enzyme and slow reaction rates
-naturally occurring inhibitors regulate metabolism
-artificial ones can be used to treat disease, kill pests, or study how enzymes work
irreversible inhibition
inhibitor covalently bonds to side chains in the active site and permanently inactivates the enzyme
reversible inhibition
inhibitor bonds noncovalently to the active site and prevents substrate from binding
competitive inhibitors
compete with the natural substrate for binding sites
uncompetitive inhibitors
bind to the enzyme-substrate complex, preventing release of products
noncompetitive inhibitors
bind to the enzyme at a different site (not the active site)
