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Flashcards in Enzyme Categories Deck (49):
1

6 classes of enzymes

1. oxidoreductases
2. transferase
3. hydrolase
4. lyase
5. isomerase
6. ligase

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oxidoreductase formula

Aox+Bred--> Ared + B ox

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oxidoreductase common co-enzymes

NADH, NADPH, FADH2

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oxidoreductase common enzyme names

1. dehydrogenase
2. peroxidase
3. reductase

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oxidoreductase special names

1.oxidase or hydroxylase
*transfer O2 atoms to water or to substrate and water
2. cytochrome p450
3. oxygenases: transfer both O2 atoms to substrate

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transferase formula

AB + C --> A + BC

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transferase enzyme name meaning

the name is the chemical group that is transferred or what chemical is synthesized

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transferase special names

1. aminotransferases--> transfer an amine group
2. kinase--> transfer a phosphate group
3. synthase--> indicates what kind of product is formed (glycogen synthase)

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hydrolase formula

CX+ H20 --> C-H + X-OH
where X= O, N, or S
**all split bonds by splitting water

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hydrolase special names

1. protease
2. esterase
3. phosphatase
4. peptidase
5. urease

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what do lyases do?

the "catch all:"
1. cleave C-C, C-O, C-S, and C-N bonds by means other than oxidation or hydrolysis
2. form C=C bonds by removing H2O from COH-CH

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lyase example common names

1. decarboxylase
2. aldolase

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lyase reverse reaction to form bonds

synthases

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what do isomerases do

no atoms lost or added, only rearranged

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common isomerase names

1. epimerase
2. racemase
3. mutase

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ligase formula

A + B + ATP--> AB + ADP + Pi

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what do ligases do?

form C-C, C-S, C-O, and C-N bonds
*require ATP or another nucleotide

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ligase common name

synthetase

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cofactors

cofactors often derived from vitamins, metal ions can also serve as catalystic co-factors

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group carried by ATP, ADP/Pi, and AMP/PPi

1. phosphoryl groups
2. very high energy bond stores chemical energy
3. protein phosphorylation

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group carried by NADH/NAD+

-shuttle electrons for redox of biological fuels
--> help produce ATP

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group carried by NADPH/NADP+

-shuttle electrons for oxidation in biosynthesis reactions

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groups carried by FADH2/FAD or FMNH2/FMN

-shuttle electrons for redox of biological fuels
-more powerful than NAD
-always bound to a protein

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coenzyme A is a carrier molecule for...

acyl groups
R=CH3 and longer

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biotin is a carrier molecule for...

CO2
carboxylation

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tetrahydrofolate amino acid metabolism is a carrier for...

1 carbon unit
-CH3, =CH2, -COO-, to carbon or sulfur

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S-adenosylmethionine is a carrier molecule for...

methyl to oxygen or nitrogen

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pyridoxal phosphate reaction with...to catalyze....

amines, NH2 =NH to catalyze amino acid metabolism, transamination reactions

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thiamine pyrophosphate reacts with...to catalyze...

aldhydes/ketones to form decarboxylation at the R group

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4 classes or proteases

1. cysteine proteases
2. aspartic proteases
3. metalloproteases
4. serine proteases

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cysteine proteases active site

cysteine

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cysteine proteases examples

1. papain (meat tenderizer)
2. cathepsin B (lysosome)

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aspartic proteases active site

aspartate
**active at low pH

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aspartic protease examples

1. pepsin
2. HIV protease

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metalloprotease active site requirement

-metal ion usually Zn2+
-sometimes CO2+

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metalloprotease examples

1. collagenase
2. matrix metalloproteases (MMPS)

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serine protease active site

catalytic triad: asp, ser, his

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serine protease examples

1.trypsin, chymotrysin
2. elastase (connective tissue)
3. thrombin (blood clotting)

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serine proteases are inhibited by

serpins
ex: alpha-1-antitrypsin

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how do serpins inhibit proteases

1. normal catalysis involves temporary covalent attachment between protease and substrate
2. serpin mimics the normal subsrate
3. serpin binds covalently and then changes conformation to inactive the serine protease

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serpin is a suicide inhibitor

meaning that one serpin per one enzyme
** can counteract irreversibly active proteases

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anti-thrombin

-inhibits coagulation in blood clotting cascade

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alpha-1-anti-trypsin

-inhibits neutrophil elastase in lungs (protective)
-inactivated by cigarette smoke
-low levels pre-dispose towards emphysema nd cirrhosis

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prepro-enzyme

inactive enzyme as translated from mRNA that has a leader sequence for location

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pro-enzyme (zymogen)

in the right location and leader sequence cleaved but is inactive

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mature protease

other region of the protease cleaved and is active

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metal ions can have two seperate roles

1. cofactors
2.structural ligands

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structural ligands

can help protein stay folded

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catalystic ion

in the active site participates in the chemistry