Catalysts of Life

Review of Chemical Reactions A chemical reaction is a process that changes, or transforms, one set of chemicals into another Reactants are elements or compounds that enter into a chemical reaction Products are the elements or compounds produced by a chemical reaction Chemical reactions usually require energy to get started Activation energy is the energy that is needed to get a reaction started

What are enzymes? Enzymes are proteins that hasten, or speed up, chemical reactions A catalyst is a substance that speeds up the rate of a chemical reaction Enzymes are biological catalysts Enzymes speed up the reactions that take place in cells

How do enzymes work? The molecule that an enzyme binds with or acts upon is called the substrate The spot on an enzyme where the enzyme and substrate bind together is called the active site. The active site is made of deep folds created by the folding of amino acid chains Enzymes can be used over and over again after a reaction is complete

How do enzymes work? Enzymes have a specific shape Substrates also have a specific shape In order for an enzyme and substrate to bind together and react, their shapes MUST fit together This is called the lock- and-key model

How do enzymes work? If an enzyme shape does not match with a substrate, there is no reaction An enzyme’s shape can be changed if conditions are not right If an enzyme’s shape is changed due to changing conditions, then the enzyme has been denatured No reaction can occur if an enzyme’s shape is denatured Factors that affect enzyme shape pH – too acidic or too basic Temperature – too hot or too cold Enzyme concentration – how many enzymes are there?

How do enzymes work? Web Link: port.com/ /lib/ /Ani mations/Enzyme_activity.html port.com/ /lib/ /Ani mations/Enzyme_activity.html

Other factors affecting enzymes Competitive inhibitors are molecules that are similar to the substrate’s shape Competitive inhibitors get stuck in the active site and prevent the enzyme from binding with the substrate Noncompetitive inhibitors are molecules that bind near, but not at, the active site Noncompetitive inhibitors change the shape of the active site and prevent the enzyme from binding with the substrate