Group 1

RedOx rxns (involves transfer of e^-, H⁺, H^-)

usually use coenzymes like NAD⁺, NADP⁺, FAD, coenzyme Q, or O₂

Group 2

Transfer chemical group from donor to acceptor

Group 3

Hydrolytic cleavage of covalent bonds

Group 4

Non-hydrolytic cleavage of covalent bonds

Group 5

Molecular rearrangement w/i a molecule w/o change in formula

Group 6

Formation of covalent bonds between carbon and other atoms

• prosthetic groups
• coenzymes
• cofactors

• Apoenzyme is an enzyme that is missing its prosthetic group
• Holoenzyme is enzyme with prosthetic group

• loosely bound, may or may not separate
• help with transfer of fxnl group from one compound to another

• cofactor is not attached to enzyme, but is necessary for maximal activity (enzyme can still fxn w/o it)
• not necessarily specific to just one enzyme or substrate

No effect on ΔG - still same free energy difference b/w substrate and product

Decreases the activation energy ΔG* between substrate and transition state

• small portion of total enzyme
• 3-D: active site AA's brought together by the structure, are not sequential in primary structure
• substrates are weakly bound to A.S. in geometry resembling the transition state and the enzyme provides groups that enhance probability of the transition state occuring

enzyme has binding or recognition sites which the substrate binds to, causing conformational change to fit the substrate

("hand in glove" theory)

pH

Temperature

[Enzyme]

[Substrate]

• pH can affect ionization of A.S. or substrate
• pH can denature enzyme and disrupt structure

• ↑Temp → ↑ substrate KE and contact w A.S.
• If Temp ↑↑ denaturation can occur

rate of rxn ↑ as [substrate] ↑ until V_max

at V_max all available A.S. are saturated

(Michaelis-Menten kinetics - hyperbolic curve)

Michaelis constant

Michaelis-Menten EQ

K_m = [S] at ¹/₂V_{max = ^(k2+k3)/k1}

but k₂>>>k₃ so k_m = ^k2/_k1

V =(^(Vmax*[S])/_{(Km + [S])})

1. [E]<<[S]

2. Rxn occurs at steady state, [ES] constant

3. V measured immediately so that back rxn from P to ES can be ignored

E + S ↔ ES → P + E

K_m= affinity of enzyme for its substrate=^K2/_K1

if K_m, Affinity ↓

if K_m↓, Affinity ↑

k_cat = _^Vmax/[Et]

turnover rate in molecules of substrate converted to product per enzyme molecule per second

Directly proportional.

If [E] decreases by half, V decreases by half

y = mx + b

¹/_V = (^Km/_Vmax) (¹/_S) + ¹/_Vmax