Lecture 11 - Enzymes I Flashcards
The most common of all enzymatic reactions.
Redox (oxidation-reduction) reactions.
Primary f(x)s of enzymes
Lower activation energy (Ea) and stabilize the transition state)
How does one increase the production of products (according to Le Chatlier’s Principle)?
Decrease [product] or increase [reactants]
What is meant by “coupled reactions” in terms of biochemical reactions?
The energies of a set of reactions are additive. In other words, if A-> B has a (+) G, and B->D has a (-) G, they can be added together. If the sum of both G’s is (-), the reaction is OVERALL spontaneous.
G*’
-RTln([prod]/[react])
These reactions revolve around the transfer of electrons.
Oxidation-reduction reactions
Gain of an e-
Reduction
loss of e-
Oxidation
Gain of H+
Conjugate acid
Loss of H+
Acid
What portion of an enzyme determines specificity for a substrate?
Active site
Cleavage of peptide bonds
Protelytic reactions
What is the Vmax?
The maximum rate (reaction velocity) at which a reaction can occur.
What produces a maximum velocity (Vmax) in reactions?
The complete saturation of the active site on an enzyme.
3-D region or crevice that is produced after the residues from various parts of a protein come together in the 3* structure
active site
Highly unstable intermediate in enzymatic reactions
transition state
What is the “purpose” of an enzyme (specifically, HOW does an enzyme catalyze reactions)?
by lowering the activation energy of a given reaction
Why are many vitamin deficiencies the cause of enzymatically driven health problems?
Often, vitamins serve as co-factors for enzymes. W/o the co-factor, the enzyme is an “apoenzyme,” devoid of function.
An enzyme that contains its co-factor and is biologically active
holoenzyme (“holo-“ = “complete”)
Two f(x)s of metals as co-factors
Stabilize A.S. and donate e- to the chemical reaction
small organic molecules used as a co-factor
co-enzymes
An enzyme w/o its necessary co-factor
apoenzyme
Tightly bound co-enzymes are known also as _____.
prosthetic groups
Pathophysiology of scurvy
A lack of co-factor (Vit. C) for prolyl hydroxylase, prevents addition of -OH in collage
Pathophysiology of ariboflavinosis
A lack of riboflavin (Vit. B2) prevents activation of FAD; this causes decreased glutathione reductase function, and results in UV light damage to areas exposed to the sun through production of free radicals (no FAD to “snag” high energy free radicals)
enzyme that transfers e- between compounds
oxidorecutase
enzyme that moves f(x) group between compounds
transferase
catalyze hydrolysis of covalent bonds
hydrolases
Form double bonds by the addition of removal of groups
lyase
transfers a group intra-molecularly
isomerase (forms isomer)
covalently links two molecules
ligase (ligate-to join together)
