Enzymes PDF

ENZYMES  Enzymes are protein molecules in cells which work as catalysts. CLASSIFICATION PROPERTIES OF ENZYMES High degree ofspecificity for their substrates. Each enzyme will catalyse only one particular reaction Enzymes are not usedup in the reaction they catalyze they can be usedagain...

ENZYMES  Enzymes are protein molecules in cells which work as catalysts. CLASSIFICATION PROPERTIES OF ENZYMES High degree ofspecificity for their substrates. Each enzyme will catalyse only one particular reaction Enzymes are not usedup in the reaction they catalyze they can be usedagain andagain W hen enzyme react they combine with substrate S to form ES complexes Only small amount ofenzyme is neededto catalyse a lot ofsubstrate Enzymes are fast actingi.e they have a high turnover number. They can convert many molecules ofsubstrate per unit time. Enzymes are affectedby change in temperature andpH. Many enzymes work only ifa chemical called cofactor is present. Enzyme catalyzedreactions are sloweddown or stop by inhibitors  Coenzyme A coenzyme is an organic non-protein compoundthat binds with an enzyme to catalyze a reaction Coenzymes are often broadly called cofactors, but they are chemically different. A coenzyme cannot function alone, but can be reused several times when paired with an enzyme.  Isozymes Isozymes (also known as isoenzymes or more generally as multiple forms of enzymes)are enzymes that differ in amino acidsequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters (e.g. different KM values),or different regulatory properties.  Proenzymes A zymogen also calleda proenzyme is an inactive precursor ofan enzyme. A zymogen requires a biochemical change (such as a hydrolysis reaction revealingthe active site, or changingthe configuration to reveal the active site)for it to become an active enzyme. Regulation andinhibition ofenzyme Regulate:to control or direct accordingto a rule, principle or law Enzyme regulation:is the control ofreaction catalyzedby an enzyme by some effector (inhibitor or activator) OR By alteration ofsome conditions (pH)