8 - Lecture Guide

Review of Lecture 8 Questions to think about…. A/an CARBANION is the species formed when bond cleavage leaves a carbon with both electrons. IF THE CARBON LOSSES BOTH ELECTRONS CARBOCATION c+ The __ is a description of the bond-breaking and bond-forming events in a chemical reaction The TRANSITION STATE is the term for an energized arrangement of atoms in which bonds are being formed and broken prior to product formation in an enzyme-catalyzed reaction. The energy required for reactants to reach the transition state from their ground state is called the ___ of the reaction. In a ____ reaction, every collision between reactant molecules gives rise to product. Rate enhancement by the binding of reactants close to each other in the enzyme active site is called the _____. Excessive stability of the enzyme-substrate complex, which is with substrate(s) tightly bound to the enzyme is termed a/an_____. Very strong hydrogen bonds that form when the electronegative atoms are less than 0.25 nm apart are termed_____. In the catalytic triad of serine proteases, the side chain of a ____residue acts as a covalent catalyst. ____is the term applied to the catalytic mode that involves increased binding of transition states to enzymes as compared with binding of substrates or products. The four major modes of enzymic catalysis are: _______, _______, _____, and _____. Activation of an enzyme by a substrate-initiated conformation change is called ____. The most frequently found catalytic residue in the active site of enzymes is____. ______are inactive enzyme precursors activated by removal of one or more portions of the precursor molecule. What is the difference between intermediates and transition states? It is said that dehydrogenation is the most common form of biological oxidation. What species is removed from the molecule being oxidized? Why is this oxidation? Describe how an enzyme causes a specific reaction to proceed more rapidly than the same uncatalyzed reaction. Explain the methods by which a biochemist can investigate steady state enzymatic reactions. Why are special techniques required to investigate pre-steady state enzyme kinetics? Explain. STEADY STATE: SPECTROPHOTOMETRY, FLUORESENCE, & RADIOACTIVE ASSAY PRESTEADY STATE: STOPPED FLOW, TEMPERATURE JUMP What are the factors that contribute to enzyme catalysis? S P A C E S – STRAIN EFFECT P – PROXIMITY EFFECT A – ACID/BASE CATALYSIS C – COVALENT CATALYSIS E – ELECTROSTATIC EFFECT FIVE PIECES OF SHIT. Explain the role of amino acids in enzyme catalysis. How might a biochemist distinguish between catalytic and noncatalytic amino acid residues? For extra review do the following questions from your text: Page 223: #5, #6, #11, #13 Page 224: #25, #26 Page 226: #48, 50