Principles of physical biochemistry

K E Van Holde, W Curtis Johnson, Pui Shing Ho

Chapter 15 Mass Spectrometry of Macromolecules - all with Video Answers

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Chapter Questions

Problem 1

A supposedly homogeneous protein is studied by mass spectrometry. Rather than a single peak in the spectrum, the spectrograph records peaks arriving at times of $50 \mu \mathrm{s}, 35 \mu \mathrm{s}, 29 \mu \mathrm{s}$, and $25 \mu \mathrm{s}$. Show that these results are consistent with a protein homogeneous in mass.

Shazia Naz

Numerade Educator

09:50

Problem 2

The ESI-MS spectrum for a protein shows peaks at $m / Z=2960.6$ and 3552.5 . Calculate the number of charges associated with the 3552.5 peak and the molecular weight of the protein.

Susan Hallstrom

Numerade Educator

01:39

Problem 3

The following peptide fragments were generated after digestion of an 11 amino acid polypeptide with trypsin and separately with thermolysin.
TABLE CANT COPY
What is the sequence of the parent polypeptide?

Adriano Chikande

Numerade Educator

03:54

Problem 4

For the sequence ASTFHDKNWKQ,
a. Calculate the masses of the fragments resulting from chymotrypsin digestion at low $\mathrm{pH}(<5)$ and, separately, the fragments resulting from trypsin digestion.
b. Predict the B- and Y-ion daughter ion spectra from a tandem MS-MS experiment on this peptide sequence.

Nima Gharibi

Numerade Educator

04:24

Problem 5

The following MS-MS spectrum was recorded after collision-induced dissociation.
FIGURE CANT COPY
a. What is the sequence of the parent peptide?
b. Suggest a reason for why the $\mathrm{Y}_6$-ion was not observed.

Eduard Sanchez

Numerade Educator

00:42

Problem 6

Propose mechanisms for the formation of the A-daughter ions and the X-daughter ions from CID.

Erwin Ni

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