Lab 6 & 7 - Enzyme Kinetics and Inhibition for Tyrosinase

Question 1

What is tyrosinase?

Answer 1

An enzyme that catalyzes reaction using a variety of substrates

Question 2

Four reactions Tyrosinase catalyzes

Answer 2

1. The oxidation of Tyrosine
2. The subsequent oxidation of DOPA
3. The oxidation of L-DOPA to Dopachrome
4. Dopaquinone to Leukodopachrome

Question 3

What product were we detecting in the Enzyme kinetics lab?

Answer 3

Moles of Dopachrome produced per minute

Question 4

Km

Answer 4

Michaelis-Menten constant; concentration of substrate that gives half maximal activity

Question 5

Vmax

Answer 5

Maximun reaction rate by the enzyme

Question 6

Km Calculation

Answer 6

Km = 1/ -x-intercept

Question 7

Vmax Calculation

Answer 7

Vmax = 1/ y-intercept

Question 8

What did we use to inhibit tyrosinase?

Answer 8

Sodium Benzoate

Question 9

What type of inhibition did sodium benzoate perform with tyrosinase?

Answer 9

Competitive inhibition

Question 10

Beer-lambert Equation

Answer 10

A=ECl
A: absorbance (nm/min)
E: Extinction coefficient (M-1cm-1)
C: concentration (moles?)
l: 1 cm

Question 11

Lineweaver-Burke plot

Answer 11

Double reciprocal plot
x-axis = 1/[S]
y-axis = 1/Volume

Question 12

Competitive Inhibition graph

Answer 12

Same y-intercept

Question 13

Noncompetitive Inhibition graph

Answer 13

Same x-intercept

Question 14

Uncompetitive Inhibition graph

Answer 14

Parallel lines

Question 15

L-DOPA + 1/2 O2 —Tyrosinase—>

Answer 15

Dopachrome