Question

Biochemistry Question (Parts B and C)

For reference:

ACh = acetylcholine, AChE = acetylcholinesterase, x amount = unknown amount, and [ ] = concentration.

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A) 15 mL of an aq. sol. containing an x amount of ACh had a pH = 7.65 in a typical analysis. When incubated w/ AChE, the pH = 6.87 (decreased).

What is the # of moles of ACh in the 15 mL sample? Assume no buffer involved.

No need to answer part A because I worked out the math and got this:

1.7 x 10^-9 mol of ACh

Please feel free to check my work though.

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B) The same analysis needs to be run in 15 mL of a 10 mM Tris buffer at pH = 7.65.

The pKa of Tris base = 8.1.

What is [Tris] and [conjugate acid] at pH = 7.65?

I'm assuming this would be a Henderson-Hasselbalch equation?

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C) Think about the ACh reaction in 15 mL of a 10 mM Tris buffer at pH = 7.65 (initially).

Assume [ACh] = 1.7 x 10^-9 mol (same as in part A).

What is the final pH of the mixture after being incubated w/ AChE?

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Thank you!

Answer 1