FACTORS AFFECTING ENZYME ACTIVITY Flashcards
are water-soluble proteins that function as biological catalysts for the reaction involve in metabolism
enzymes
Enzyme Structure
Two general structures:
Simple enzyme
Conjugated enzyme
an enzyme composed
only of protein (amino acids chains)
Simple enzyme
an enzyme that has
a non-protein (cofactor) part in addition to a
protein part.
Conjugated enzyme
s the relatively small part of an
enzyme’s structure that is actually involved in
catalysis
active site
It is usually a _________________ location in
the enzyme.
‘crevicelike’
In this model, the active site in the enzyme has
a fixed, rigid geometrical conformation. It
explain the action of numerous enzymes.
Lock-and-Key Model
It allows for small changes in the shape or
geometry of the active site of an enzyme to
accommodate a substrate.
Induced-Fit Model
Factors affecting Enzyme Activity
- Physical Factors
- Chemical Factors
Physical Factors
- Concentration of the Substrate
- Concentration of Enzyme
- effect of pH
- effect of temperature
other
conditions being kept constant, an increase in the
concentration of the substrate will increase the
rate of activity
Concentration of the Substrate
using a highly
purified enzyme, the velocity of the reaction is
directly proportional to the concentration of the
enzyme.
Concentration of Enzyme
each enzyme requires a definite
pH zone. This has been discussed under
characteristics of enzyme action
effect of pH
for each enzyme,
there is an optimum temperature for maximal
activity.
effect of temperature
A phenomenon in which a substrate molecule is
prevented from binding to the active site of
an enzyme by a molecule that is very similar in
structure to the substrate. Thus, the inhibitor
molecule and the substrate that the enzyme
acts on “compete” for the same binding site.
Competitive Inhibition
a molecule binds
to an enzyme somewhere other than the
active site. This changes the enzyme’s threedimensional structure so that its active site can
still bind substrate with the usual affinity, but is
no longer in the optimal arrangement to stabilize
the transition state and catalyze the reaction.
Noncompetitive Inhibition
