Biochemistry Enzymes PDF

BIOCHEMISTRY SHAYNE ESCULTOR-ALBASE, LPT, MAEd 6.53 Learning Outcomes: 1. Explain the role of enzymes in biological systems 2. Categorize enzymes based on reactions they catalyzed 3. Explain different factors that can affect enzyme activity 4. Explain the mechanis...

BIOCHEMISTRY SHAYNE ESCULTOR-ALBASE, LPT, MAEd 6.53 Learning Outcomes: 1. Explain the role of enzymes in biological systems 2. Categorize enzymes based on reactions they catalyzed 3. Explain different factors that can affect enzyme activity 4. Explain the mechanisms as to how enzymes can catalyze biochemical reactions 5. Describe inhibition and regulation of enzymes  OVERVIEW One of the most important process in the human body is catalysis, which is the process of speeding up the rate of a chemical reaction by the addition of a catalyst. Catalysts are not consumed during a reaction but merely help the reaction occur more rapidly. In the body, these catalysts are known as enzymes (derived from the Greek word “en” meaning inside and “zyme” meaning yeast). Each cell in the human body comprises thousands of different enzymes because almost every reaction in a cell requires a specific enzyme. EVALUATE THE STATEMENTS BELOW: All enzymes are proteins All proteins are enzymes CHOICES: A. 1st statement is correct B. 2nd statement is correct C. Both statements are correct D. Neither of the statements are correct  General Properties of Enzymes They are mostly globular proteins. They are endowed with high catalytic power. They are highly specific. Many enzymes require factors for activity. TERMS DEFINITION simple enzyme is an enzyme composed only of protein (amino acids) not bound to any nonproteins conjugated enzyme is an enzyme that has a nonprotein part in addition to a protein part apoenzyme is the protein part of a conjugated enzyme or holoenzyme enzyme lacking an essential cofactor cofactor is the nonprotein part of a conjugated enzyme or holoenzyme serve functions similar to those of prosthetic groups but bind in a transient, dissociable manner either to the enzyme or to a substrate such as ATP. prosthetic group Tightly bound cofactor to the apoenzyme holoenzyme is the biochemically active conjugated enzyme produced from an apoenzyme and a cofactor Intact and functional enzyme containing all cofactors/ coenzyme Coenzyme or cosubstrate is a small organic molecule that serves as a cofactor in a conjugated enzyme activator the inorganic cofactor Substrate (S) is the reactant in an enzyme-catalyzed reaction biomolecule that enzymes react with Product (P) the biomolecules formed by enzyme mediated reactions metal-activated enzymes Enzymes that require a metal ion cofactor metalloenzymes. enzymes that contain tightly bound metal ions Nature of an Enzyme How do enzymes make reactions fast? Enzymes lower the activation energy of the reaction. OVERVIEW: Mechanism of Enzyme action Enzyme Active Site - the relatively small part of an enzyme’s structure that is involved in catalysis; usually a 3-dimensional “crevicelike” location at the enzyme. Enzyme-Substrate Complex the intermediate reaction species that is formed when the substrate bind to the active site of an enzyme. 2. Induced-Fit Model (Daniel F. Koshland) is a result of the enzyme’s flexibility the enzyme active site, although not exactly complementary in shape to that of the substrate, is flexible enough that it can adapt to the shape of the substrate. FACTORS AFFECTING RATE OF ENZYMATIC REACTION ENZYME INHIBITION Medically Useful Enzymes Medically Useful Enzymes