Enzymes Flashcards
most enzymes are _____ in nature
protein
a substance that alters or speeds up a chemical reaction without itself being chemically changes at the end of the reaction which therefore, required in small quantities.
Catalyst
enzymes are not chemically changed..
YES
PROPERTIES OF ENZYMES
✓ Can act on only one type of substrate
(specific)
✓ Always produce the same end
products
✓ Although they take part in the
reaction, they are not used up
✓ Enzymes are proteins, so they are
denatured by heat or some chemicals
o Denaturing – involves a
change of shape in the
enzyme molecule so that it
cannot combine with the
substrate
✓ Individual enzymes – work best at a
particular temperature and pH
o Acidity
o Alkalinity
involves a change of shape in the enzyme molecule so that it cannot combine with the substrate
Denaturing
The capability of the enzymes to bind with a substrate is based on 2 models:
LOCK & KEY MODEL
INDUCED – FIT MODEL
In LOCK & KEY MODEL ______ must fit into the active site of the enzyme – hence the specificity of the enzyme
substrate
in induced-fit model, ______ – is not rigid as the Lock- and- key Model, but flexible. That is, the site changes in conformation upon binding to a substrate in
order to yield an enzyme – substrate fit
active site
4 variables of enzyme activity
i. Temperature
ii. pH
iii. Enzyme concentration
iv. Substrate concentration
are proteins and therefore undergo
all the reactions that proteins do
Enzymes
enzymes can be coagulated by
▪ heat
▪ alcohol
▪ strong acids
▪ alkaloidal reagents
In enzymes, the higher the temperature, the ______
the rate of reaction
faster
Best temperature for enzyme
function
the temperature at which
the rate of a reaction involving an
enzyme is the greatest (optimum
temperature)
Effect of Concentration:
o With all the chemical reactions – the
speed is increased with an increase in
concentration of reactants
o Increased concentration of substrate
– the rate of the reaction will increase
until available enzyme becomes
saturated with substrate
o Increased amount of enzyme – rate of
reaction will increase, assuming an
unlimited supply of substrate
With all the chemical reactions – the
speed is _______ with an increase in
concentration of ______
increased ; reactants
