BICH 409: Exam 3 material and concepts

Catalytic power

How much faster an enzyme makes a reaction compared with the uncatalyzed reaction

Proximity

The enzyme brings reacting molecules close together

Orientation

The enzyme positions in the correct direction so they can react efficiently

Electrostatic catalysis

Enzyme stabilize electrical charges that develop during the transition state

Covalent catalysis

The enzyme attaches itself to the substrate temporarily to help the reaction happen (covalent bond)

Nucelophile

Electron pain donor, attacks an electron deficient center

electrophile

Electron pair accepts, gets attacked by a nucleophile

Shiff base formation

Acts as an electron sink (meaning it stablizes transition state that have high energy negative charge)

Metalloenzyme

Enzyme binds it metal cofactor tightly

Metal activated enzyme

Enzyme binds its metal weakly

Carbonic anhydrase

Conversion of carbon dioxide into bicarbonate

First order is at

Low substrate concentrations

Zero order is at

High substrate concentration

Micahelis menten equation

V=vmax (s)/km+ (s)

Low km

Higher substate affinity, tighter binding

High km

Lower substrate affinity, weaker binding

Solving for km

vmax(s)/v - (s)

Solving substrate

vkm/vmax-v

Half max velocity

vmax/2 when (s)=km

Kcat=

vmax/(E)

High kcat

Enzyme converts substrate quickly when saturated

Low km enzyme

reaches half max velocity at low sub concentrations

High kcat and Km

Greater catalytic efficiency at low substrate concentrations

Competitive inhibition

• Apparent km increases.

• Vmax unchanged

• Same y intercept

Noncompetitive inhibition

• Km unchanged

• vmax decreases

• same x intercept

Mixed noncompetitive inhibition

• apparent km changes (increase or decrease)

• apparent vmax decreases

• Both KM and Vmax change

Uncompetitive inhibtion

• Apparent km decreases

• Apparent vmax decreases

• Lines are parallel