ENZYMES

WHAT IS AN ENZYME? organic catalyst catlalyst - assists the reaction but remain unchanged when the reaction is over. Reusable each chemical reaction requires one enzyme

modify the rate of reactions structure large complex proteins consisting of one or more polypeptide chains whose names end in –ase substrate – substance worked on by enzyme

ENZYME SUBSTRATE maltase maltose lipase lipids protease proteins amylase amylose

protein nature – either all protein or proteinc with non-protein parts, called coenzymes – also known as VITAMINS active site – formation of pockets into which reacting molecules fit

HOW DO ENZYMES WORK? 2 MODELS OF ENZYME FUNCTION ENZYME-SUBSTRATE COMPLEX “LOCK AND KEY” MODEL

ENZYME SUBSTRATE COMPLEX enzyme forms a temporary association with a substance whose reaction rate is affected close physical association between enzyme and substrate is formed  enzyme-substrate complex

enzyme action takes place in enzyme-substrate complex upon completion of reaction, enzyme and product(s) separate, enzyme is available for another reaction

LOCK AND KEY MODEL particular enzyme will usually only form a complex with one particular type of substrate

WHAT INFLUENCES ENZYMES? TEMPERATURE AMOUNT OF ENZYME & SUBSTRATE pH

TEMPERATURE reaction rate increases until an optimum temperature enzyme action rate decreases At high temperatures, enzymes denature

AMOUNT OF ENZYME & SUBSTRATE when an excess of substrate is added, the rate of enzyme action increases to a point then remains fixed as long as the enzyme concentration remains constant

pH enzymes work best at different pH ranges

**a pH of 7 provides the optimum environment** acids - high H+ concentration which means LOW pH – below 7 bases – low H+ concentration which means HIGH pH – above 7