Probing Mechanisms of Peptide Bond Formation & Catalysis Using Models Model of Koga Uses molecular recognition by a crown ether to bind a model of the.

Slides:

Advertisements

Similar presentations

Fundamentals of Biochemistry

Advertisements

The Chemical Nature of Enzyme Catalysis

Catalytic Strategies. Basic Catalytic Principles What is meant by the binding energy as it relates to enzyme substrate interactions? –free energy released.

Lecture 17 –Exams in Chemistry office with M’Lis. Please show your ID to her to pick up your exam. –Quiz on Friday –Enzyme mechanisms.

Hypothetical substrate docking in enzyme’s active site. Substrate is geometrically and electronically compatible with active site. Enzymes are also.

Enzyme Mechanisms.

Modes of Enzymatic Catalysis 1._________________ modes A.General _______________ Catalysis B.__________________ Catalysis 2.___________________ modes A.______________________.

Biochemistry Sixth Edition

Lecture 12: Enzyme Catalysis

Chymotrypsin Chymotrypsin is one of the serine proteases.

Lecture 13: Mechanism of Chymotrypsin

Mechanisms of Enzyme Action

Catalytic Mechanism of Chymotrypsin slide 1 Chymotrypsin –Protease: catalyze hydrolysis of proteins in small intestine –Specificity: Peptide bond on carboxyl.

Average = = C+ Standard deviation = 16 A = 131+B- = A- = C+ = B+ = C = B= C- =

Design of a novel globular protein with atomic-level accuracy.

Two Substrate Reactions

Enzyme Mechanisms: Serine Proteases

Chapter 3 PROTEIN FUNCTION. All proteins bind to other molecules Binding is selective.

The Nature of the Active Site Questions we want to ask: 1.Looking at the reactants and products, what type of reaction has occurred Hydrolysis, Condensation,

Review Enzyme “constants” Reversible inhibition

Allosteric Enzymes Allosteric: Greek allo + steric, other shape Allosteric enzyme: an oligomer whose biological activity is affected by other substances.

Chapter 14 Mechanisms of Enzyme Action

By: Dario Marotta 10/23/ ELASTASE A SERINE PROTEASE.

Chymotrypsin Lecture Aims: to understand (1) the catalytic strategies used by enzymes and (2) the mechanism of chymotrypsin.

Review session for exam-III Lectures The concept of “induced fit” refers to the fact that: A. Enzyme specificity is induced by enzyme-substrate.

Enzyme Mechanisms and Inhibition

Catalytic Mechanisms.

Enzymes (If you don’t have the energy, we can help!)

Mechanism of lysozyme Lysozyme digests bacterial cell walls by breaking  (1- 4) glycosidic bonds between (N- acetylmuramic acid (NAM) and N-acetylglucosamine.

Chapter 6.1 and 6.2: Introduction to Enzymes

Chapt. 8 Enzymes as catalysts

CHMI E.R. Gauthier, Ph.D. 1 CHMI 2227E Biochemistry I Enzymes: - catalysis.

Mechanisms of Enzyme Action. Transition (TS) State Intermediate Transition state = unstable high-energy intermediate Rate of rxn depends on the frequency.

CHMI E.R. Gauthier, Ph.D. 1 CHMI 2227E Biochemistry I Enzymes: - catalysis.

A Lock-and-Key Enzyme Animation. Enzyme Substrate Active Site.

Enzyme Catalysis 10/08/2009. Regulation of Enzymatic Activity There are two general ways to control enzymatic activity. 1. Control the amount or availability.

Binding features that promote catalysis

Time to Connect……. Enzyme Activity is amount of enzyme that

Enzyme Rate Enhancement

CHAPTER 6 Energy, Enzymes, and Metabolism. Energy and Energy Conversions Energy is the capacity to do work Potential energy is the energy of state or.

The Behavior of Proteins: Enzymes, Mechanisms, and Control Feb 16, 2016 CHEM 281.

Enzymes: A Molecular Perspective

Zymogen/proenzyme (inactive enzyme precursor)

Serine Proteases Components of the enzymatic pocket:

Serine Proteases A large group of enzymes that cleave amide bond

OMICS Journals are welcoming Submissions

Mechanism of proteolysis by the serine protease chymotrypsin

A catalyst lowers activation energy.

Enzyme Catalytic Mechanisms

CHYMOTRYPSIN INTRO MISSION: STRATEGY: PROFILE: RELATIVES: SUSPECTS:

Chemistry 501 Handout 6 Enzymes Chapter 6

Enzyme Mechanisms.

Mechanisms of Enzyme Action

The Nature of the Active Site

A catalyst lowers activation energy.

What enzymes are regulated?

A catalyst lowers activation energy.

Serine proteases Named because they use a serine residue to cut peptide bonds Possess a catalytic triad His 57 Asp 102 Ser 195 Use 2 different types of.

A catalyst lowers activation energy.

A catalyst lowers activation energy.

A catalyst lowers activation energy.

A catalyst lowers activation energy.

Serine proteases have a reactive serine

A catalyst lowers activation energy.

A catalyst lowers activation energy.

A catalyst lowers activation energy.

Lecture 8 Enzyme Kinetics

Michael A. McDonough, Christopher J. Schofield Chemistry & Biology

Presentation transcript:

Probing Mechanisms of Peptide Bond Formation & Catalysis Using Models Model of Koga Uses molecular recognition by a crown ether to bind a model of the substrate –Crown ethers:

Koga chemically modified the crown ether to contain 2 thiol (SH) groups to mimic reactions on NRPS

Molecular Recognition good lv group (monitored by UV)

Intramolecular trans-acylation: reactive thioester becomes stable amide Crown ether model demonstrates concepts of: proximity of reactive functionalities molecular recognition

We have examined peptide bond formation on the ribosome –Catalytic mechanism: The ribosome “workbench” rRNA Substrate-assisted catalysis What about breaking the peptide bond (i.e. proteolysis)? Catalyzed by proteases and/or peptidases

Chymotrypsin Part of the serine proteases (trypsin, elastase, etc) These enzymes often work in concert Serine residue in active site acts as nucleophile Chymotrypsin cuts peptide bonds at aromatic residues

1) Substrate (peptide) binds to form complex 2)1 st tetrahedral intermediate 3)Acyl-enzyme

5)2 nd tetrahedral intermediate 4) H 2 O attacks 6) Release from enzyme

Test of Mechanism? How do we know Ser is the original nucleophile? –Use irreversible inhibitor to react with Ser Ser 195 is more nucleophilic than other serine residues –Nearby His 57 & Asp 102 are important for catalytic activity. How? –Methylate His nitrogen  10 3 decrease in activity!