This set of Protein Engineering Multiple Choice Questions & Answers focuses on “Structural Study – Mass Spectroscopy – 2”.
1. Which of the following can be used as a detector in Mass Spectrometry?
a) ESI
b) GC
c) HPLC
d) Conversion diode
View Answer
Explanation: Conversion diode can be used as a detector in Mass Spectrometry. ESI, GC, and HPLC cannot be used as detectors in Mass Spectrometry. ESI is an ionization technique. GC and HPLC are sample inlet techniques.
2. What is the monoisotopic mass of threonine?
Given data: Mass of the most abundant isotope of Carbon (C°)=12.0000,
Mass of most abundant isotope of Hydrogen (H°)=1.0078,
Mass of most abundant isotope of Oxygen (O°)=15.9949,
Mass of most abundant isotope of Nitrogen (N°)=14.0031.
a) 111.0451
b) 121.024
c) 201.258
d) 101.047
View Answer
Explanation: The monoisotopic mass of threonine is 101.047
The chemical formula of threonine is C4H7O2N
Formula:
Monoisotopic mass=[no. of carbon atoms x (C°) + no. of hydrogen atoms x (H°)+ no. of oxygen atoms x (O°) + no. of nitrogen atoms x (N°)] Hence, the monoisotopic mass of threonine=4 x (12.000) + 7 x (1.0078) + 2 x (15.9949) + (14.0031)
monoisotopic mass of threonine = 101.047.
3. Which of the following can be used as an analyzer in Mass Spectrometry?
a) ESI
b) Electron multiplier
c) Microchannel plate
d) TOF
View Answer
Explanation: TOF can be used as an analyzer in Mass Spectrometry. TOF stands for Time of Flight. ESI, electron multiplier and microchannel plate cannot be used as an analyzer in Mass Spectrometry. Electron multiplier and microchannel plate are detectors used in MS.
4. Which of the following is a soft ionization technique?
a) Chemical ionization
b) Electron impact ionization
c) Gas chromatography
d) Fast atom bombardment
View Answer
Explanation: Fast atom bombardment (FAB) is a soft ionization technique. A soft ionization technique leads to the formation of ions with low internal energies and little consequent fragmentation. Chemical ionization, electron impact ionization, and gas chromatography are not soft ionization techniques.
5. All mass analyzers operate under vacuum.
a) False
b) True
View Answer
Explanation: The above statement is true. All mass analyzers operate under vacuum to minimize collisions between ions and air molecules. Without a high vacuum, the ions produced in the source will not reach the detector.
6. What is the average mass of proline?
Given data: Average mass of Carbon (C)=12.011,
The average mass of Hydrogen (H)=1.008,
The average mass of Oxygen (O)=15.999,
The average mass of Nitrogen (N)=14.007.
a) 91.113
b) 99.216
c) 93.216
d) 97.116
View Answer
Explanation: The average mass of proline is 97.116
The chemical formula of proline is C5H7ON
Formula:
Average mass=[no. of carbon atoms x (C) + no. of hydrogen atoms x (H) + no. of oxygen atoms x (O) + no. of nitrogen atoms x (N)]
Hence, the Average mass of proline=5 x (12.011) + 7 x (1.008) + (15.999) + (14.007)
The average mass of proline = 97.116.
7. Which of the following type of mass analyzer accelerates charged ions along a long tube known as flight tube?
a) Ion trap mass analyzer
b) Quadrupole mass analyzer
c) Orbitrap
d) TOF
View Answer
Explanation: TOF type of mass analyzer accelerates charged ions along a long tube known as flight tube. TOF stands for Time of Flight. It accelerates ions at different velocities depending on their mass-to-charge ratio.
8. Which among the following cannot be used as a detector in Mass Spectrometry?
a) Electron multiplier
b) Array detector
c) Microchannel plate
d) Electron impact chamber
View Answer
Explanation: Electron impact chamber cannot be used as a detector in Mass Spectrometry, because it is a technique used for sample inlet. Electron multiplier, array detector, and microchannel plate can be used as a detector in Mass Spectrometry.
9. What is the monoisotopic and average mass of valine?
Given data: Mass of the most abundant isotope of Carbon (C°)=12.0000,
Mass of most abundant isotope of Hydrogen (H°)=1.0078,
Mass of most abundant isotope of Oxygen (O°)=15.9949,
Mass of most abundant isotope of Nitrogen (N°)=14.0031,
The average mass of Carbon (C)=12.011,
The average mass of Hydrogen (H)=1.008,
The average mass of Oxygen (O)=15.999,
The average mass of Nitrogen (N)=14.007.
a) 99.068 and 99.2361
b) 99.216 and 99.326
c) 99.111 and 99.321
d) 99.068 and 99.132
View Answer
Explanation: The monoisotopic and average masses of valine are 99.068 and 99.132 respectively.
The chemical formula of valine is C5H9ON
Formula:
Monoisotopic mass=[no. of carbon atoms x (C°) + no. of hydrogen atoms x (H°) + no. of oxygen atoms x (O°) + no. of nitrogen atoms x (N°)]
Hence, the monoisotopic mass of valine=5 x (12.000) + 7 x (1.0078) + (15.9949) + (14.0031)
monoisotopic mass of valine = 99.068
The chemical formula of valine is C5H9ON
Formula:
Average mass=[no. of carbon atoms x (C) + no. of hydrogen atoms x (H) + no. of oxygen atoms x (O) + no. of nitrogen atoms x (N)]
Hence, the Average mass of valine=5 x (12.011) + 9 x (1.008) + (15.999) + (14.007)
The average mass of valine = 99.132.
10. Which of the following cannot be used as an analyzer in MS?
a) Ion trap
b) Quadrupole
c) TOF
d) ESI
View Answer
Explanation: ESI cannot be used as an analyzer in Mass Spectrometry because it is an ionization technique. Ion trap, quadrupole, and TOF are types of typical analyzers used in Mass Spectrometry.
11. Which of the following is not a soft ionization technique?
a) ESI
b) FAB
c) MALDI
d) CI
View Answer
Explanation: Chemical ionization (CI) is not a soft ionization technique. ESI, FAB, and MALDI are soft ionization techniques. They lead to the formation of ions with low internal energies and little consequent fragmentation.
12. Which of the following can be used as a detector as well as an analyzer in Mass spectrometry?
a) Conversion diode
b) Array detector
c) Electron multiplier
d) Ion cyclotron Fourier transform
View Answer
Explanation: Ion cyclotron Fourier transform can be used as a detector as well as an analyzer in Mass spectrometry. Conversion diode, array detector, and electron multiplier can only be used as a detector in MS.
13. Which of the following type of mass analyzer makes use of a combination of electric and magnetic fields and captures ions in a region of vacuum system?
a) Quadrupole mass analyzer
b) Ion cyclotron resonance
c) TOF
d) Ion trap mass analyzer
View Answer
Explanation: Ion trap mass analyzer is a type of mass analyzer that makes use of a combination of electric and magnetic fields and captures ions in a region of a vacuum system. Quadrupole mass analyzer, Ion cyclotron resonance, and TOF do not make use of a combination of electric and magnetic fields.
14. What is the missing component in the flowchart shown below?
a) ESI
b) GC
c) HPLC
d) Mass analyzer
View Answer
Explanation: Mass analyzer is the missing component in the flowchart shown above. A mass analyzer separates the beam into its components. ESI, GC, and HPLC cannot be the missing component as they cannot separate the beam into its components.
15. What is the monoisotopic mass of proline?
Given data: Mass of the most abundant isotope of Carbon (C°)=12.0000,
Mass of most abundant isotope of Hydrogen (H°)=1.0078,
Mass of most abundant isotope of Oxygen (O°)=15.9949,
Mass of most abundant isotope of Nitrogen (N°)=14.0031.
a) 91.527
b) 43.519
c) 87.063
d) 97.052
View Answer
Explanation: The monoisotopic mass of proline is 97.052
The chemical formula of proline is C5H7ON
Formula:
Monoisotopi mass=[no. of carbon atoms x (C°) + no. of hydrogen atoms x (H°) + no. of oxygen atoms x (O°) + no. of nitrogen atoms x (N°)]
Hence, the monoisotopic mass of proline=5 x (12.000) + 7 x (1.0078) + (15.9949) + (14.0031)
monoisotopic mass of proline = 97.052.
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