lecture 7 introduction to enzyme
Post on 07-Jul-2018
214 Views
Preview:
TRANSCRIPT
-
8/19/2019 Lecture 7 Introduction to Enzyme
1/9
Lecture 7
Enzymes:
Introduction
-
8/19/2019 Lecture 7 Introduction to Enzyme
2/9
Catalyst
• substance that increase rates of achemical reaction
• does not effect equilibrium• remain unchanged in overall
process
• reactants bind to catalyst,products are released
-
8/19/2019 Lecture 7 Introduction to Enzyme
3/9
Catalysts increase product formation by(1) lowering the energy barrier (activation
energy) for the product to form(2) increases the favorable orientation ofcolliding reactant molecules for productformation to be successful (stabilize transition
state intermediate)
-
8/19/2019 Lecture 7 Introduction to Enzyme
4/9
Catalytic Poer
• Enzymes can accelerate reactionsas much as !"!# over uncatalyzed
rates$• %rease is a good e&le:
– Catalyzed rate: '&!"()sec
– %ncatalyzed rate: '&!" *!")sec
– +atio is !&!"!( $
-
8/19/2019 Lecture 7 Introduction to Enzyme
5/9
pecificity• Enzymes selectively recognize
proper substrates over othermolecules
• Enzymes produce products in very
high yields * often much greaterthan -./
• pecificity is controlled by
structure * the unique fit ofsubstrate ith enzyme controls theselectivity for substrate and the
product yield
-
8/19/2019 Lecture 7 Introduction to Enzyme
6/9
Classes of enzymes!0 1&idoreductases 2 catalyze o&idation*reduction reactions
34568
90 ransferases 2 catalyze transfer of functional groups from onemolecule to another0
'0 ydrolases 2 catalyze hydrolytic cleavage
(0 Lyases 2 catalyze removal of a group from or addition of agroup to a double bond, or other cleavages involving electron
rearrangement0.0 Isomerases 2 catalyze intramolecular rearrangement0
#0 Ligases 2 catalyze reactions in hich to molecules are ;oined0
Enzymes named for the substrates and type of reaction
-
8/19/2019 Lecture 7 Introduction to Enzyme
7/9
-
8/19/2019 Lecture 7 Introduction to Enzyme
8/9
Co*enzymes
• 4on*protein molecules that help enzymesfunction
• 5ssociate ith active site of enzyme• Enzyme < Co*enzyme 2 holoenzyme• Enzyme alone 2 apoenzyme• 1rganic co*enzymes = thiamin, riboflavin,
niacin, biotin• Inorganic co*enzymes = >g
-
8/19/2019 Lecture 7 Introduction to Enzyme
9/9
Kinetics
• study of reaction rate
• determines number of steps involved
• determines mechanism of reaction
• identifies rate!limiting" step
top related