BIOD60H3 Lecture 9: Lecture 9.docx

72 views10 pages

purplecicada400

18 Oct 2012

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Progress of the reaction: transition state and intermediates during catalysis. The progress of a reaction can be represented by an energy diagram, or energy profile. Figure 6. 1 (slide 2) is an example that shows the conversion of a substrate (reactant) to a product in a single step. The y axis shows the free energies of the reacting species. The x axis, called the reaction coordinate, measures the progress of the reaction, beginning with the substrate on the left and proceeding to the product on the right. This axis is not time but rather the progress of bond breaking and bond formation of a particular molecule. The transition state occurs at the peak of the activation barrier this is the energy level that must be exceeded for the reaction to proceed. The lower the barrier the more stable the transition state and the more often the reaction precede.

Related Questions

1) Chymotrypsin (Mr 21600) degrades peptides. Under saturation condition (0.4M), the substrate glycyltyrosinylglycine (GYG), is cleaved at a rate of 1.43 moles/min, Kcat is 100 sec, and Km is 108 mM. The rate of the uncatalyzed reaction is 1.2 micromoles/min. show your work:

a. What is the enzyme concentration?

b. What substrate concentration will give a velocity that is Â¼ of Vmax?

c. What is the difference between the activation energy for the reaction catalyzed by chymotrypsin and the activation energy for the uncatalyzed reaction? Calculate the value that the activation energy is changed by the enzyme.

d. What are the products of the reaction?

Suppose a reaction, Xï Y, starts out with an energy of a, and uncatalyzed has an activation energy of b. The reaction can be catalyzed by the enzyme switcheroo, with an activation energy of c that is less than that of b. The final energy of the reaction is d. Suppose that at high temperatures, the uncatalyzed activation energy is lowered such that it is between b and c, while the switcheroo catalyzed activation energy remains the same. At this high temperature, is the reaction more likely to proceed catalyzed by switcheroo or uncatalyzed? Explain your reasoning.

salmonreindeer765

Part 1: Which statement is not associated with covalent catalysis by enzymes?

A) It never involves coenzymes B) A transient covalent bond is formed between the enzyme and the substrate

C) When the reaction is complete, the enzyme returns to iits origional state D) A new pathway from substrate(s) to product(s) is formed that is faster than the uncatalyzed reaction.

Part 2: Which statement is false for a competitive inhibitor?

A) It does NOT change the Vmax B) a'= 1.0 C) it is irreversible D) It is often structurally similar to substrate

Part 3: Which statement about enzymes is FALSE?

A) A substantial amount of their catalytic power results from binding of the substrate(s) through weak interactions. B) They lower the activation energy of a reaction. C) They alter the overall thermodynamics of a reaction. D)They increase the rates of reactions by 10^5-fold to 10^17-fold.

BIOD60H3 Lecture 9: Lecture 9.docx

Document Summary

Get access

Related Documents

BIOCH200 Lecture Notes - Lecture 1: Activation Energy, Stereospecificity, Protein Structure

BCH2011 Lecture Notes - Lecture 10: Reaction Coordinate, Solvation Shell, Activation Energy

BCH2011 Lecture Notes - Lecture 10: Reaction Coordinate, Activation Energy, Reaction Intermediate

Related Questions