Enzymes and Binding Sites Biology Past Paper PDF

Chapter 3 Questions I Define enzyme and how / why they are used in biological systems Enzymes are globular proteins acting body's...

Chapter 3 Questions I Define enzyme and how / why they are used in biological systems Enzymes are globular proteins acting body's as the catalysts They. are used biological systems by in speeding up time for reaction to reach equilibrium - lower the activation of Enzymes energy a reaction 2. Define ligand, binding site / active site, substrate, allosteric sites · of binding/active the site: a small specific area that the substrate a , producteyme reversibly ligand : molecule that bind to specific · a or ion can a & site on a target through non-covalent bonds or covalent bonds - ex : hormones, substrates. Substrate : starting material , a molecule that an enzyme interacts with to catalyze a specific biochemical reaction. · allosteric site: a bindingthe site on enzymes that is different from active site. · binding site : a place on a enzyme for substrates to bind , can be allosteric or active 3. Describe features of binding sites on an enzyme and the binding interactions involved. the features: specificity: binding site has a specific shape chemical and properties tailored to recognize and bind a particular substrate. Induced fit model. complementary shape : the 3D structure of the binding sites complements the shape of the substrate , allowing precise reactions. flexibility : binding sites are flexible to accommodate the substrate better. Chemical : the acid complementary amino residues lining the chemical binding site posses groups that interact with the Substrate The interactions involve binding mainly non-covalent bonds and sometimes covalent bonds. bonds: between hydrogen polar amino acid residues in the binding site and functional groups (hydroxyl or amino groups). ionic interactions : between charged residues in the site (lysine arginine) binding the. substrate , and oppositely charged groups on acids (valine , hydrophobic interactions : nonpolar amino leucine) in the binding site interact with nonpolar regions of the substrate to exclude water. Van der Waals forces : nonspecific interactions weak , between closely aligned nonpolar atoms of the enzyme and substrate. Arise from the shape of the binding site. aromatic residues (phenylanine pistacking between : , tyrosine) and aromatic groups positively charged or residues interacting with aromatic rings.  covalent bonds (rare) : substrate can form a covalent bond with acid residue temporary an amino in the active site enzymes *A - Describe methods in which enzymes catalysis reactions and amino acid groups that may be involved in each. Enzymes Catalysis reactions by bringing reactants together positions , reactants bonds in the correctly for reaction weakens , reactants provides , provides acid/base catalysis , the ucleophilicgroupsandstablisa ar bonds Amino acid , hisyes, thatmight a. involved include , L-serine/L-Cysteine , 15. Discuss the theory of induced fit and how it explains enzyme activity and specificity induced fit theorydescribes act The a site that an is nearly the substrate. This kind of shape.ISfor said bonding to the changeshape of explains eny ainduced This the me activity allows Enzyme bind. release fit substrates to a efficiently and quickly. This also makes the enzyme adaptable. 6. Be able to interpret Michaelis-Menten and Lineweaver–Burk graphs to find Km, Vmax Michaelis-Menten Plot equation : v Umax [S] = constant: Km = [S] V = reaction velocity Umax = maximum velocity of the enzyme-catalyzed reaction concentration at is 12 km = Substrate which the reaction velocity Vmax [S] = concentration of the substrate A high value of km indicates weak binding km indicates A low value of strong binding How to determine Vmax and Km: Vmax : look for the plateau of the curve /Where no longer increases with 25] km : 12 Vmax Y-axis locate the point where V = on Find the corresponding substrate concentration [S] on the X-axis Lineweaver-Burk Plot double ThelineweaverBurk potis the recipofsee + Its a straight-line plot of 'v(y-axis) vs. 1/25] (x-axis) slope = km/Vmax Y-intercept = 1/ Vmax X-intercept -"(km = How to determine Vmax from y-intercepti Vmax : Yy-intercept Calculate km from the x-intercept km = - "lx-intercept 7 - Define Km and Vmax and how they relate to enzyme kinetics. · km : Michaels Menton constant - - equal to the substrate concentration at which the rate of the enzyme catalyzed reaction value · This is half ofits maximum relates to Kinetics because it reflects subsume affinity , reaction rate behavior, and enzy um · efficient rate at which an eny a can catalyze a reaction when the substrate concentration is saturated It reflects the enzyme's catalytic capacity. 8. Define isozymes and their role in drug discovery Isozymes are molecules that catalyze the Same reaction but differ in structure substrate primary and tissue distribution. , specificity inhibit These isozymes make it possible to specific enzymes lessening , side effects of drugs.