Enzymes, Part 1 Flashcards
- major classes of enzymes - biochemical properties of enzymes
1
Q
enzymes
A
- act as mediators for all reactions in biological systems
- are substrate-specific protein catalysts
- they increase the rate of reactions without being changed or used up during process
- selectively channel reactants (called substrates) into energetically favorable pathways
- 3D structures of proteins generates sites for other molecules allowing reversible binding of them
2
Q
oxidoreductases
A
- catalyze reactions in which one molecule is oxidized while the other is reduced, transfer of electrons H+ (oxidases, reductases, dehydrogenases)
- ex: lactate – lactate dehydrogenase – pyruvate
3
Q
transferase
A
- transfer carbon, nitrogen or phosphate containing groups
- ex: serine – serine hydroxymethyl transferase – glycine
4
Q
hydrolases
A
- enzymes that catalyze a hydrolytic cleavage reaction (=t transfer or functional groups to water) (nucleases and proteases)
- catalyze cleavage of bonds by addition of water
- ex: urea – urease – carbone dioxide and ammonia
5
Q
lyases
A
- catalyze the cleavage of C-C, C-S, and C-N bonds, addition of groups to double bonds or formation of double bonds by removal of groups
- ex: pyruvate – pyruvate decarboxylase – acetaldehyde + carbon dioxide
6
Q
isomerases
A
- catalyze the rearrangement of bonds within a single molecule, transfer or groups within molecules to yield isomeric forms
- catalyze racemization of optical or geometric isomers
- ex: methylmalonyl CoA – methylmalonyl CoA mutase – succinyl CoA
7
Q
ligases
A
- join together (ligate) two molecules in an energy-dependent process (DNA ligase joins 2 DNA molecules), formation of C-C, C-S, C-O and C-N bonds by condensation actions coupled to cleavage of ATP or similar cofactor
- catalyze formation of bonds btwn carbon and O,S,N coupled to hydrolysis of high-energy phosphates
- ex: pyruvate – pyruvate carboxylase – oxaloacetate
8
Q
polymerases
A
- catalyze polymerization reactions such as synthesis of DNA and RNA
9
Q
proteases
A
- break down proteins by hydrolyzing bonds btwn amino acids
10
Q
kinases
A
- catalyze the addition of phosphate groups to molecules
11
Q
ATPases
A
- hydrolyze ATP (Na, K ATPase)
12
Q
synthases
A
- synthesize molecules in anabolic reactions by condensing 2 smaller molecules together (ATP synthase)
13
Q
phosphatase
A
- catalyze hydrolytic removal of a phosphate group from a molecule
14
Q
synthetase vs synthase
A
synthetase requires ATP, synthase does not require ATP
15
Q
phophatase vs phosphorylase
A
phosphatase uses water to remove phosphoryl group, phosphorylase uses Pi to break a bond and generate a phosphorylated product
