Flashcards in Enzymes Deck (100)
What are functions of enzymes?
-reduces activation energy
-enables biological rections to proceed at faster rates
properties of enzymes?
-enzymes can be hydrolyzed by dilute acids or alkali to form free AA or low molecular weight peptides
-E can be broken down by proteases to form AA or peptides with participation of H2O
-E can respond to typical common protein tests (ie. ninhydrin and lowry)
-E is comprised of AA linked together by peptide bonds
what can hydrolyze enzymes?
what do they form?
dilute acids or alkali; or peptides
forms free AA or low molecular weight peptides
what links AAs together?
sizes of collagen, myosin, trypsin, amylose?
def of proenzyme?
immature and inactive enzyme
def of holoenzyme?
complete enzyme that is active
it is bound to its cofactor
def of apoenzyme?
enzyme that requires a cofactor
it is inactive
becomes active when it is bound to a cofactor
def of a prosthetic group?
the non-protein part that forms a part of a protein
examples of prosthetic groups?
metal ions: Ca, Fe, Zn
relationship between holoenzyme and prosthetic group?
-sometimes, the holoenzyme is the whole protein
-other times, the holoenzyme needs the essential non-protein part for the protein to be active (ie. the prosthetic group)
what are features of the enzyme active site? (3)
what are 2 events that occur at the active site?
binding and transformation
Relationship between binding and transformation?
-binding of substrate preceeds transformation
-not all binding leads to transformation
-no transformation occurs without binding
4 levels of enzyme specificity?
1. bond specificity
2. group specificity
3. absolute specificity
how are enzymes bond specific?
-E acts on compounds with one type of bond (ie. lipase can act on lipids as long as they have an ester bond)
-can have relative or low specificity
How are enzymes group specific?
when an enzyme acts on a group of closely related compounds
-ie. pepsin can hydrolyze peptide bonds where there is are aromatic AAs
-ie trypsin can hydrolyze peptide bonds where there are basic AA
how are enzymes absolutely specific?
when enzyme acts on one single substrate
-ie lactase only acts on lactose. Sucrase only acts on sucrose
-very high specificity
how are enzymes sterospecific?
when enzyme acts on one isomer of a molecule
-ie L-AA oxidase acts only on L-AA
why is it necessary to understand specificity in a baking company?
-linear starch has alpha(1-4) bonds.
-branched starch has alpha (1-6) bonds
-linear starch is stickier than branched starch
how many enzyme classifications are there? what are these classifications based on?
based on recommendation of enzyme commission of the international union of biochemists
also based on types of reaction catalyzed
what is the numbering system that enzyme nomenclature
enzyme commission = EC
EC = (A.B.C.D) --> letters are digits
A = 1st group
B = sub group
C = sub sub group
D = numbering
what are the 6 enzyme classifications?
what are oxidoreductases?
can catalyze oxidation or reduction reactions
ie. polyphenol oxidase (PPO), glycose odidase (GOX), peroxidase, lipoxygenase
what are transferases
transfers groups from one substrate (the donor) to another substrate (Acceptor)
what are hydrolyases
catalyzes cleavage or hydrolysis of larger molecules into smaller molecules with H2O as a co-reactant
eg. proteases and lipases
what are lyases
removes group from one molecule, leaving behind a product with a lower molecular weight (usually with unsaturated bonds)
eg. histidine decarboxylase, pectin, lyase
what are isomerases
catalyzes the conversion of molecules into their isomers
eg. glucose isomerase
what are racemases and epimerases?
isomerase enzymes that catalyzes the inversion of stereochemistry
racemases: catalyzes sterochemical inversion around the asymmetric carbon atom (in a substrate has only one center of asymmetry)
epimerases: catalyzes sterochemical inversion of the configuration around an asymmetric carbon (in a substrate with more than one center of assymmetry)