Enzymes Flashcards
How do enzymes catalyse reactions
activation energy is the energy needed for a reaction to proceed
molecules in free solution will only react by “bumping” into each other
enzymes increase rate of reaction by lowering activation energy
How do enzymes lower activation energy
entropy reduction - enzymes “force” substrate to be correctly oriented by binding them in the formation needed to be in for the reaction to proceed
desolation - weak bonds between the substrate and enzyme essentially replace most or all of the H bonds between substrate and aqueous solution
induced fit - conformational changes occur in the protein structure when the substrate binds
How does the rate of an enzyme-catalysed reaction vary
concentration of enzyme and substrate
temperature
pH
Define Michaelis Menken
used to plot kinetics of enzyme reactions
Michaelis constant (Km) = how specific the enzyme is for the substrate - low value = good fit
Vmax = how fast a reaction proceeds is proceeding when the enzyme is saturated with substrate
what is competitive inhibition
inhibitor binds to active site inhibiting the binding of the substrate
reversible
Vmax unchanged
Km increases because it takes more substrate to overcome the inhibition
What is non-competitive inhibition
binds to secondary binding site - allosteric site
changes conformation of active site preventing binding of substrate
nonreversible
Vmax decreased
Km remains same
Why is enzyme activity measured in a clinical setting
detection of suspected disease at pre-clinical stage
confirmation of suspecting disease and assessing severity
localisation of disease to organ
characterisation of organ pathology
assessing the response to therapy
organ function assessment
detection of inherited metabolic diseases and vitamin deficiencies
What factors influence enzyme activity in samples
hypoxia - loss of oxygen supply due to occlusion or inadequate oxygenation
cellular damage - due to chemicals or drugs
physical damage - surgery, burns, radiation etc
immune disorders - anaphylaxis, autoimmune disease
microbiological agents - bacteria, fungi, virus
genetic defects
nutritional disorders
Use of enzyme assays
laboratory methods for measuring enzymatic activity
vital for study of enzyme kinetics and enzyme inhibition
