Enzymology. Lecture 2 by Rumeza Hanif. How enzymes work?. Uncatalyzed reactions tend to be slow. Neutral pH, mild temperature, aqueous environment inside cell are needed for biological molecules
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Lecture 2 by RumezaHanif
E+S ↔ ES ↔ EP ↔ E+P
ES: Transient complex of enzyme with substrate
EP: Transient complex of enzyme with product
Energy in the biological system is described as free energy, G
G: The energy associated with a chemical reaction that can be used to do work.
The free energy of a system is the change in its enthalpy (H) minus the product of the temperature (Kelvin) and the entropy (S) of the system
Enthalpy (H) describes the energy it takes for a substance to change from one phase to another (i.e. solid to liquid.). It reflects the number and kinds of bonds.
Amino Acids Proteins (Endergonic)
ATP ADP +P (Exergonic)
Reaction Coordinate 1: ATP ADP+P (the exergonic breakdown of ATP has a large negative free energy)Reaction Coordinate 2: Glucose + P Glucose 6 Phosphate (The formation of Glucose 6 phosphate yields a product of higher energy than the 2 reactants, for this endergonic reaction ΔG is positive)
The relationship between Keq and ΔG’o can be described by thy expression
ΔG’o= -RT In Keq
R= Gas constant 8.315 J/mol.K
T= Absolute temperature 298 K (25 C)
Chapter 6, Lehninger Principles of Biochemistry, David L. Nelson and Michael M. Cox. 5thEd (How enzymes work)
Chapter 1, Lehninger Principles of Biochemistry, David L. Nelson and Michael M. Cox. 5thEd, pg 22-25