Enzymes Flashcards
all chemical reactions that occurs within an organism
metabolism
simpler substance combined to form complex substances
- endergonic reaction
anabolism-
- complex substance broken down to form simpler substance
- exergonic reaction
catabolism
example of anabolism
synthesis of glycogen
example of catabolism
hydrolysis of glycogen
function of catalyst
speed up chemical reaction but stay unchanged at the end of the reaction
6 characteristics of an enzyme
has catalytic properties, specific active site, reversible reaction, enzyme specificity, very efficient, affected by many factors
types of enzyme specificity
absolute specificity, group specificity, linkage specificity
absolute specificity
catalyze only one reaction
act only on specific functional group.
eg; amino, methyl, phosphate
group specificity
act on particular type of chemical bond
linkage specificity
how does an enzyme speed up chemical reactions?
by lowering the activation energy
- unstable condition
- substrate activated; breaking and making bonds can occur
- increases the chances of successful collision
what happens at transition state
energy is released
ΔG < 0
reactants > products
exergonic reaction
energy is absorbed
ΔG > 0
reactants < products
endergonic reaction
energy generated by catabolic process used by cells to perform anabolic process
energy coupling
how to lower the activation energy
- orienting substrates correctly
- straining substrate bonds
- provide favorable microenvironment
the active site in the enzyme has a fixed, rigid and geometrical conformation
lock & key model
active site changes shape so that substrate can fit into it
induced fit
only substrate with complementary shape can accommodate the site
lock & key model
substrate with non-complementary shape can accommodate the site
induced fit
active site will return to its original shape when the product is released
induced fit
6 factors influencing enzyme activity
pH value, temperature, substrate concentration, enzyme concentration, cofactor, inhibitor
below optimum temperature
reaction will increase as the temperature increases until it reaches the optimum temperature
above optimum temperature
enzyme will be denatured and lose its catalytic properties
atom in enzyme will vibrate violently, breaking the bonds which held the enzyme in shape.
above optimum temperature
enzyme concentration
reaction will increase as the enzyme concentration increases
rate of reaction increases with increasing substrate concentration up to the
point of saturation.
2 types of inhibition
reversible & irreversible inhibition
molecules will bind permanently with the enzyme by covalent bond
irreversible inhibition
cyanide, insecticide is the example of molecules for
irreversible inhibition
2 types of reversible inhibition
competitive & non-competitive(allosteric site) inhibitor
has a similar shape to natural substrate and fits temporarily on active site
competitive inhibition
no structural similarities to natural substrate and attached to allosteric site
non-competitive inhibition
effect can be reduced if substrate concentration increases
competitive inhibition
effect cant be reduced if substrate concentration increases
non-competitive inhibition
malonic acid molecule is the inhibitor for
competitive inhibition
amino acid isoleucine is the inhibitor for
non-competitive inhibition
example of enzyme cofactor
inorganic ion, prosthetic group, coenzymes
non protein components that are bound tightly or loosely required for certain enzymes for their efficient activity
enzyme cofactors
attaches temporarily
eg; zink, chlorine
inorganic ions
binds tightly and permanently
eg; FAD
prosthetic group
- binds loosely and temporarily
- obtained from vitamins
- eg; NAD+
coenzymes
enzyme-protein portion
apoenzyme
a non protein component
cofactor
apoenzyme + cofactor =
haloenzyme
a molecule that binds to an enzyme at a site other than the active site and change the enzyme activity
allosteric regulation
6 classes of enzymes
hydrolase, oxidoreductase, transferase, lyase, isomerase, ligase
- formation of 2 products from a substrate by hydrolysis
- lipase, amylase
hydrolase
- non-hydrolytic addition or removal of groups from substrates
- aldolase
lyases
- rearrangement of atoms within a molecule
- glucose-phosphate isomerase
isomerase
- join together 2 molecules by the break down of ATP
- phosphokinase
ligases
- transfer of a functional group from one substance to another
- transaminase kinase
transferase
- involved in oxidation and reduction
- cytochrome oxidose
oxidoreductase
