Lecture 9-10: Theisen Flashcards Preview

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Flashcards in Lecture 9-10: Theisen Deck (109)
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1

Oxioreductases

Transfer electrons from a donor to an acceptor

2

Transferases

Transfer a functional group between molecules

3

Isomerases

Rearrange/isomerize molecule

Intramolecular

4

Lyases

"Synthases" add or remove atoms to or from a double bond (from water, ammonia, CO2)

5

Ligases

Synthetases-form bonds w/ hydrolysis of ATP

6

Hydrolases

Cleave bonds via the addition of water-hydrolysis

Transfers functional groups to water

7

Catalysts

Increasing the rate of chemical reactions

8

How do enzymes affect energy of activation?

By forming an enzyme-substrate complex---lowering the energy of activation

9

Enzymes get substrates to their:

Transition state

10

Uncatalyzed rate w/ carbonic anhydrase

Significantly slower [ 10-1 vs 10^6] -1,000,000 X / sec

11

Sir Archibald Edward Garrod

1st making connection btw disease and fundamental errors in biochem. Rxn's. [alkaptonuria] coined the term inborn errors of metabolism

12

2 Reaction drivers:

Mass action [Le Chatelier's Principle]
Coupled reactions [input of energy]

13

MAss action / Le Chatelier's

Increase in [ ] of products= more reactants
Increase [ ] of reactants = more products

Opposite direction from adjustment made

14

Coupled reactions [input of energy]

Coupling rxn's is possible if they share a common intermediate

15

What increases rxn velocity?

Enzymes

16

What indicates whether the rxn will proceed w/ or w/o input of energy? Spontaneous

Gibbs free energy deltaG

17

What Gibbs energy is favored?

Negative

18

Oxidation-reduction reactions

Electron donor will reduce the electron acceptor (reducing and oxidizing agents)

19

Acid-base rxn's

Weak acid dissociates in water==releases proton and conjugate base

Weak base combines w/ protons in water. Forming its conjugate acid

20

Characteristic of enzymes r/t specificity

3D structure and active site.

Specificity of binding depends on the precisely defined arrangement of atoms in the active site.

21

Where does substrate bind to enzyme?

Active site

22

Enzyme substrate complex formation: 2 types

Lock n key and induced fit

23

Example of enzyme specificity:

proteases cleave peptides btw carboxyl and amino group.

24

What limits the reaction rate?

Substrate occupying all the available catalytic sites of enzymes

Increasing substrate [ ], reaction rates hit a Vmax.

25

What evidence shows ES complex formed??

X-Ray crystallography. Cytochrome P450 is bound to its substrate camphor- surrounded by residues of the active site and a heme cofactor

26

What is the enzyme active site

3D cleft or crevice formed from the residues of various protein regions an occupies call total volume

Contains a unique microenvironment, usually void of water, and controls the proper shape, pH and polarity for substrate binding and chemical reactivity

27

First law thermodynamics

Conservation of energy. Can't be created or destroyed

28

Transition state

Defined as intermediate structure that is not the substrate and not yet the product----

Unstable and highest free energy

29

Gibbs free energy of activation

The difference in free energy of the transition state and the substrate ----this can be lowered by enzymes

30

Chymotrypsin

Consists of 3 chains. Side chains of the catalytic triad. There are also 2 interstrand and 2 intra strand disulfide linkage.