Question

Enzyme Kinetics Lab Guide

Table 2: Absorbance values per minute for varied substrate concentrations

Time (min)	Tube A (0mM)	Tube B (2.0mM)	Tube C (5.0mM)	Tube D (8.0mM)	Tube E (12.0mM)	Tube F (20.0mM)
0	0	0.012	0.066	0.066	0.076	0.191
1	0.011	0.045	0.128	0.128	0.164	0.200
2	0.017	0.096	0.190	0.190	0.219	0.241
3	0.009	0.122	0.234	0.234	0.294	0.313

Table 3. Absorbance values versus substrate concentration at a constant time (from Table 2)

Concentration (mM)	0 mM	2.0 mM	5.0 mM	8.0 mM	12.0 mM	20.0 mM
Absorbance	0.017	0.96	0.133	0.190	0.219	0.241

Table 4. Rate (velocity) values at each respective substrate concentration

Concentration (mM)	0 mM	2.0 mM	5.0 mM	8.0 mM	12.0 mM	20.0 mM
Rate (mM/min)

Using concentrations and the corresponding absorption values from Table 3, create a graph of absorbance vs. concentration. Using Beer’s Law, determine the molar absorptivity (slope).

Determine the rate of reaction for each concentration. You can obtain the rate of reaction (initial velocity) by taking the slope of 2 mM obtained from the graph of Table 2 and dividing by the slope of the line from Table 3 and repeat for each concentration.) This is the rate of reaction for each concentration. Place this data in Table 4.

y = 0.0104x + 0.0676
R² = 0.8244

i need help with table 4 please, thank you

Answer 1

Firstly I guess there's a mistake in Table 3. The absorbance data corresponding to 2mM might be 0.096 instead of 0.96. Then it would make complete sense.

Now helping you with table 4:

1. Calculate slope of graph from table 3 with concentrations in x-axis and absorbance in y-axis. You will get a straight line and let's say you get the slope as X. Units: 1/mM.

2. Similarly calculate the slopes for all the tubes in table 2 with time in x-axis and absorbance in y-axis. You will get 6 graphs with 6 different slopes each corresponding to a particular tube with a particular concentration. Here too you will be getting straight lines. Let the slopes obtained be ​​​​Y(a), Y(b), Y(c)... respectively. The units will be 1/min.

3. Now in table 4 the rate reactions will be slope of table 3 divided by slopes of table 2 i.e. Y(a)/X, Y(b)/X, Y(c)/X,.... respectively. As you can also figure out the units will be mM/min. Place these 6 values in the empty spaces of table 4.

Thank you