Energetics and Enzymes Flashcards
Define enzyme
protein that acts as a catalyst to induce chemical changes in other substances, itself remaining apparently unchanged by the process
Define Gibbs Free Energy
amount of energy within a molecule that could perform useful at a constant temperature
What must GFE be for reaction to occur spontaneously?
negative
Write equation for GFE for reaction A + B —-> C + D
GFE = (C+D)-(A+B)
How do enzymes work?
lowers energy barriers that stop reactions taking place
What is a couple reaction?
Reactions that take place in cell are energetically unfavourable so they are coupled with an energetically favourable one
Why does coupling reactions work?
sum of GFE is negative so will proceed
What do the majority of biochemical reactions rely on?
hydrolysis of high-energy phosphate bonds e.g. ATP
Do enzymes affect GFE?
no, just increase rate
Define transition state
particular conformation of substrate in which atoms of the molecule are rearranged, geometrically and electronically, so reaction proceeds
How does an enzyme work?
bind to substrate at AS, arrange substrate so bonds strained, residues in enzyme make/bread bonds by altering electron arrangement, oxidation or reduction
Describe Lock & Key model
substrate shape complementary to AS
Describe Induced Fit
substrate proximity indices change in enzyme conformation so AS forms
What does lysozyme do?
hydrolysis of sugar molecules in bacterial cell wall so they lyse
What 2 acidic resides does lysozyme contain?
Glu35 and Asp52
