Chapter 19: Enzymes

biomolecule that catalyze biological reactions

substrate

Look at notes

“ase”

the type of reaction catalyzed

they are historical

trypsin

chymotrypsin

pepsin

Proteases (break peptide bond)

Lipases (break ester bond)

Lactases (break glycosidic bond)

protein or peptide

lipids

carbohydrates

1. Oxidoreductases

2. Transferases

3)Hydrolases

4. Lyases

5. Ismoerases

6. Ligases

Reduction; dehydrogenases, oxidases

Transfer a functional group; kinases (transfer of phosphoryl group)

hydrolysis; proteases, lipases

add or remove a group from a double bond (make or remove); decarboxylases

isomerization; mutases

make or break a bond; carboxylases

difference in energy between reactants and products

it does not affect it

lowers it form a normal one but speeds up the rate of the reaction

it is the formation of the enzyme-substrate complex

it is the conversion of substrate into product

location on enzyme that binds the substrates

rigid and perfectly complentary

flexible, not as strict but still complementary

ability of an enzyme to bind only 1 or a few structurally similar substrates

1. Absolute

2. Group Specifitcy

3. Linkage specificity

4)Stereochemical specificity

enzyme can only bind to one substrate

can bind similar molecules (with similar structures/functional groups)

enzyme that catalyzes the reaction will either “make” or “break” the same type of bond

enzyme can recognize stereochemical differences (D vs. L)

substrate is in an intermediate form (features of both the substrate and the product)

1. conformational change

2. proper proximity and orientation

3. Enzyme can modify its minoenvironment

enzyme puts “stress” on the substrate

substrate is bound in a correct location (in active site) for catalysis to occur

cofactors and/or coenzymes

a compound or molecule that binds directly to an enzyme and is necessary for it’s function (for the ability to catalyze) NOT A SUBSTRATE

just the enzyme, no interactions, inactive (no substrate, coenzyme, or cofactors)

The active site can be altered to allow for bonding of the cofactor and the substance (active)

1. Allesteric regulation

2. proenzyme/zymagens

3. Protein modification

molecule binds to the enzyme (not at the active site) that can either increase or decease the rate of a reaction

in active enzyme precursor (digestive enzymes: go through a hydrolysis reaction to remove a peptide fragment to make the active form of the enzyme)

chemical change of an amino acids R group (phosphorylation/dephosphorylation)

1. pH optimum

2. Temperature optimum

1. Irreversible inhibition: covalently binds to active site

2. Reversible inhibition: molecule can bind but also get released (Competitive inhibition)

proteases or peptides (digestive)

break a covalent bond with addition of water

loss of organized structure (unfolding of 2, 3, and sometimes 4 structures)

9

Glycine, alanine, valine, leucine, isoleucine, phenylalanine, proline, tryptophan, methionine

6

Serine, threonine, tyrosine, cysteine, asparagine, glutamine

2

Aspartate and Glutamate

3

Histidine, Arginine, lysine