lecture 4 web: pollev.com/ucibio text: to: 37607 type in: 169964
Post on 31-Dec-2015
219 Views
Preview:
TRANSCRIPT
Lecture 4
Web: pollev.com/ucibio
Text: To: 37607Type in: 169964 <your
question>
Enzymes and reactions
Spontaneity = ___
Enzyme = Decrease G# = _________________Mechanism = “Induced fit”
Rate = ___
“Active site” ________________ stabilize TS
Decreasing DG‡: Proximity + Orientation
Active site:
Bring products togetherIn precise orientation
Not just binding!
Forces change in substrate conformation as well!
Active site interactions can stabilize the TSActive site residues can initiate reactions
Keep molecules under “strain” to facilitate reaction
Different enzymes = Different mechanisms
Glc Glc-6-P: Enzyme = Hexokinase
http://web.chem.ucsb.edu/~molvisual/ABLE/induced_fit/index.html
Specificity of enzymes - Isomers
Specificity of enzymes - Stereoisomers
Effects of specificity – Tastes!
Effects of specificity – Calories!
http://commons.wikimedia.org/wiki/File:D_et_l_glucose.png
Effects of specificity – Treatment!
3D shape is important!
OK. Fine. So the shape of the active site is importantHow is the shape formed?
Formation of active sites
Active site review
Small part of total enzyme
3D architecture is importantSpecific residues importantNot necessarily contiguous residues
How does an active site form?
Protein must “fold”into structureHow does protein “fold?”
First, understand protein compositionProteins made up of _____________
What is an amino acid?
Molecule with _____ group and ___________ group
Each amino acid has a different “R” groupThere are _____ different amino acids
H2
NCOOH
C
R
H
Amino acids, pH and charge
Amino acid titration curve
Asp titration curve
Amino acids in cells…
H2
NCOOH
C
R
H
The Peptide bond: Joining amino acids
Nomenclature: Nt -> Ct
Charge on peptides is cumulative
OK. What does this all have to do with enzymes?
What is needed for proteins to fold correctly?Can we design experiment to test?
top related