Enzyme Categories Flashcards
6 classes of enzymes
- oxidoreductases
- transferase
- hydrolase
- lyase
- isomerase
- ligase
oxidoreductase formula
Aox+Bred–> Ared + B ox
oxidoreductase common co-enzymes
NADH, NADPH, FADH2
oxidoreductase common enzyme names
- dehydrogenase
- peroxidase
- reductase
oxidoreductase special names
- oxidase or hydroxylase
* transfer O2 atoms to water or to substrate and water - cytochrome p450
- oxygenases: transfer both O2 atoms to substrate
transferase formula
AB + C –> A + BC
transferase enzyme name meaning
the name is the chemical group that is transferred or what chemical is synthesized
transferase special names
- aminotransferases–> transfer an amine group
- kinase–> transfer a phosphate group
- synthase–> indicates what kind of product is formed (glycogen synthase)
hydrolase formula
CX+ H20 –> C-H + X-OH
where X= O, N, or S
**all split bonds by splitting water
hydrolase special names
- protease
- esterase
- phosphatase
- peptidase
- urease
what do lyases do?
the “catch all:”
- cleave C-C, C-O, C-S, and C-N bonds by means other than oxidation or hydrolysis
- form C=C bonds by removing H2O from COH-CH
lyase example common names
- decarboxylase
2. aldolase
lyase reverse reaction to form bonds
synthases
what do isomerases do
no atoms lost or added, only rearranged
common isomerase names
- epimerase
- racemase
- mutase
ligase formula
A + B + ATP–> AB + ADP + Pi
what do ligases do?
form C-C, C-S, C-O, and C-N bonds
*require ATP or another nucleotide
ligase common name
synthetase
cofactors
cofactors often derived from vitamins, metal ions can also serve as catalystic co-factors
group carried by ATP, ADP/Pi, and AMP/PPi
- phosphoryl groups
- very high energy bond stores chemical energy
- protein phosphorylation
group carried by NADH/NAD+
- shuttle electrons for redox of biological fuels
- -> help produce ATP
group carried by NADPH/NADP+
-shuttle electrons for oxidation in biosynthesis reactions
groups carried by FADH2/FAD or FMNH2/FMN
- shuttle electrons for redox of biological fuels
- more powerful than NAD
- always bound to a protein
coenzyme A is a carrier molecule for…
acyl groups
R=CH3 and longer
biotin is a carrier molecule for…
CO2
carboxylation
tetrahydrofolate amino acid metabolism is a carrier for…
1 carbon unit
-CH3, =CH2, -COO-, to carbon or sulfur
S-adenosylmethionine is a carrier molecule for…
methyl to oxygen or nitrogen
pyridoxal phosphate reaction with…to catalyze….
amines, NH2 =NH to catalyze amino acid metabolism, transamination reactions
thiamine pyrophosphate reacts with…to catalyze…
aldhydes/ketones to form decarboxylation at the R group
4 classes or proteases
- cysteine proteases
- aspartic proteases
- metalloproteases
- serine proteases
cysteine proteases active site
cysteine
cysteine proteases examples
- papain (meat tenderizer)
2. cathepsin B (lysosome)
aspartic proteases active site
aspartate
**active at low pH
aspartic protease examples
- pepsin
2. HIV protease
metalloprotease active site requirement
- metal ion usually Zn2+
- sometimes CO2+
metalloprotease examples
- collagenase
2. matrix metalloproteases (MMPS)
serine protease active site
catalytic triad: asp, ser, his
serine protease examples
- trypsin, chymotrysin
- elastase (connective tissue)
- thrombin (blood clotting)
serine proteases are inhibited by
serpins
ex: alpha-1-antitrypsin
how do serpins inhibit proteases
- normal catalysis involves temporary covalent attachment between protease and substrate
- serpin mimics the normal subsrate
- serpin binds covalently and then changes conformation to inactive the serine protease
serpin is a suicide inhibitor
meaning that one serpin per one enzyme
** can counteract irreversibly active proteases
anti-thrombin
-inhibits coagulation in blood clotting cascade
alpha-1-anti-trypsin
- inhibits neutrophil elastase in lungs (protective)
- inactivated by cigarette smoke
- low levels pre-dispose towards emphysema nd cirrhosis
prepro-enzyme
inactive enzyme as translated from mRNA that has a leader sequence for location
pro-enzyme (zymogen)
in the right location and leader sequence cleaved but is inactive
mature protease
other region of the protease cleaved and is active
metal ions can have two seperate roles
- cofactors
2. structural ligands
structural ligands
can help protein stay folded
catalystic ion
in the active site participates in the chemistry
