06 - CHAPTER 6 Enzymes Biochemistry: The Molecular Basis of...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Biochemistry: The Molecular Basis of Life, 4/e McKee/McKee Copyright © 2009 by Oxford University Press, Inc. C H A P T E R 6 Enzymes
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Overview ! Almost all reactions in an organism are enzyme-catalyzed. Enzymes – most important molecular machines. ! Catalyst = substrate that increases the rate of a reaction but remains unchanged by the reaction. ! Enzymes: protein catalysts (and ribozymes). ! Enzymes: highly specific catalysts for the substrates! ! Enzyme-catalyzed reactions – μ s-to-ms (acceleration of reaction rates by 10 7-19 -fold). ! Enzymes: catalysts acting at moderate (‘life’) conditions. ! Enzymology = part of biochemistry that studies enzyme structure, function (kinetics), mechanisms.
Background image of page 2
FIGURE 6.1 A Catalyst Reduces the Activation Energy of a Reaction Basics of catalysis: A + B " C ‘Successful’ collision of A & B, ie A & B must have activation energy (temperature, nonprot. catalysts, conc.) Transition state = reaction intermediate. Δ G A , free energy of activation = energy to transform 1 mole of substrate into the transition state. Catalysts decrease Δ G A by changing the reaction path but don’t affect Δ G and therefore increase the reaction rate. 6.1 Properties of enzymes
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Enzyme specificity – due to uniquely shaped active sites : - amino acid side chains take an active role in the catalysis - optimal orientation of the substrate to achieve the transition state at a lower energy Cofactor = nonprotein component of an enzyme (eg metal ion or complex org. molecule = coenzyme ). Holo enzyme (holoprotein): + cofactor Apo enzyme (apoprotein): - cofactor. E. Fischer (1890s): Lock-and-key model D. Koshland (1958) : Induced-fit model FIGURE 6.2 The Induced-Fit Model
Background image of page 4
X-ray structure of the light - activated c-di-GMP phosphodiesterase Tyagi et al., 2008. Chem Physics 354 :130; Barends et al., 2009 Nature 459 :1015 BLUF FAD EAL c-di-GMP pGpG Klebsiella pneumoniae BlrP1
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Active site of BlrP1 & mechanism of catalysis Barends et al., 2009. Nature 459 :1015 , Mg 2+ (Mn 2+ ) , W1, W2, catalytic water H O : H W2 + H O : H W1 δ -
Background image of page 6
6.2 Classification of enzymes Enzyme nomenclature: IUB assigns EC # 6 major enzyme classes 1. Oxidoreductases = redox rxn (alcohol dehydrogenase: CH 3 CH 2 OH + NAD + # CH 3 CHO + NADH) 2. Transferases = transfer of a group from a donor to an acceptor groups. 3.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/15/2010 for the course MOLB 3610 taught by Professor Gomelsky during the Fall '10 term at Univeristy of Wyoming- Laramie.

Page1 / 22

06 - CHAPTER 6 Enzymes Biochemistry: The Molecular Basis of...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online