m6 - Protein Function:Protein Binding Introduction Ch2,...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Protein Function:Protein Binding Introduction Ch2, Page 36 Ch3, Page 73-79, 82-86
Background image of page 1

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

View Full DocumentRight Arrow Icon
Protein Function: Protein binding
Background image of page 2
V max and K m Characterize Enzymatic Reactions Michaelis - Menten Kinetics • An equation that takes into account an enzyme’s… 1) Affinity for its substrate 2) Ability to catalyze a reaction • Requirements for Michaelis-Menten Kinetics 1) The amount of enzyme is kept constant 2) The enzyme concentration is lower than the substrate concentration
Background image of page 3

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

View Full DocumentRight Arrow Icon
V max and K m Characterize Enzymatic Reactions Michaelis - Menten Kinetics - K m (Michaelis constant) : The substrate concentration that yields a 1/2 maximal reaction rate; where K m =1/2 V max Rate of formation of rxn products Concentration of substrate • 2 parameters: - V max : the maximum velocity/rate of the reaction at saturating substrate concentration -The smaller the K m the smaller the [substrate] needed to reach V max (Correlates an enzyme’s affinity for its substrate). How can a K m value be used to determine an enzyme’s affinity for its substrate?
Background image of page 4
Enzymes in a Common Pathway • Enzymes taking part in the same pathway are generally located in the same cellular compartment (e.g. cytosol, same organelle). - Products can diffuse from one reaction to the next enzyme in the pathway. -Diffusion is random and slow… an inefficient process for moving molecules between dispersed enzymes. -Cells have evolved mechanisms for bringing enzymes in a common pathway into close proximity.
Background image of page 5

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

View Full DocumentRight Arrow Icon
Enzymes in a Common Pathway • Diffusion is greatly reduced or eliminated when enzymes are associated into multimeric enzymes or are assembled on a common scaffold . -This arrangement allows the products of one reaction to be channeled directly to the next enzyme in the pathway. - Pyruvate dehydrogenase : a complex of 3 distinct enzymes that converts pyruvate into acetyl CoA in mitochondra.
Background image of page 6
Enzymes in a Common Pathway • In some cases, separate proteins have been fused together at the genetic level to create a single multidomain, multifunctional enzyme. A B C
Background image of page 7

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

View Full DocumentRight Arrow Icon
How are enzymes regulated? Chapter 3, Page 82-86 • Chemical modifications • Allosteric Regulation –Feedback Inhibition • Regulating protein levels
Background image of page 8
Enzyme Regulation via Chemical Modification • Adding or removing a phosphate can activate or inactivate a protein • Phosphorylation can change the conformation of the ligand binding site
Background image of page 9

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

View Full DocumentRight Arrow Icon
Allosteric Regulation • A mechanism whereby the activity of an enzyme is either inhibited or activated by a regulatory molecule that binds to a site, called the allosteric site (distinct from the active site) • This binding to the allosteric site produces a conformational change of the active site…either simulating or inhibiting the enzymes ability to catalyze a reaction.
Background image of page 10
Negative Regulation Feedback Inhibition • When the amount of the end- product is high, it inhibits an enzyme that functions early in the reaction pathway
Background image of page 11

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

View Full DocumentRight Arrow Icon
Feedback Inhibition: Allosteric modulation • In synthesizing a molecule there are many steps, each using a different enzyme.
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/05/2008 for the course LIFESCI 3 taught by Professor Staff during the Fall '06 term at UCLA.

Page1 / 62

m6 - Protein Function:Protein Binding Introduction Ch2,...

This preview shows document pages 1 - 13. Sign up to view the full document.

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