James' Unwanted Blood Clots
The antithrombin III test measures how well James' plasma inhibits thrombin.
This part of the tutorial show how enzyme kinetics are used in this test.
This part of the tutorial is ment to illustrate one application of enzyme kinetics.
A physician would not be called upon to conduct this test. Rather, the physician would send the appropriate sample to the appropriate laboratory.
Consequtly, this section is designed to provide the student with a general overview of the test.
That's right:
There would be very little change in the reaction rate.
The recommended substrate concentration is 55 times higher than the Km (180μM/3.24μM), so the enzyme will be nearly sturated with syubstrate even if the substrate concentration is cut in half.
If you wish, you can use the Michaelis-Menton equation to come up with a quantitative answer to the question.
Quantitative answer: At 180 μM substrate Vi is 98% of Vmax and at 90μM substrate Vi is 96.5% of Vmax. Consequently, the reduction in substrate concentration will only cause about a 2% decrease in Vi.