[47] Mass Spectrometry

Question 1

What is the main purpose of mass spectrometry in molecular biology?

Answer 1

It’s used for the identification, characterization and quantification of proteins and other biomolecules.

Question 2

What is the basic principle of mass spectrometry?

Answer 2

It measures the mass-to-charge ratio (m/z) of ions to identify and quantify molecules.

Question 3

What is the m/z ratio in mass spectrometry?

Answer 3

It refers to the mass (m) of an ion divided by its charge number (z).

Question 4

What are the main stages of a mass spectrometry process?

Answer 4

• Ionization of sample
• Separation of ions based on their m/z ratio
• Detection of separated ions

Question 5

What does the term ‘ionization’ mean in the context of mass spectrometry?

Answer 5

It’s the process of converting molecules into charged ions for detection and analysis.

Question 6

What is the mass spectrometer component that separates ions based on their m/z ratio called?

Answer 6

It’s called an analyzer.

Question 7

What type of information can be obtained from the mass spectrum produced by a mass spectrometer?

Answer 7

• The molecular weight of the sample
• The structural information of the sample

Question 8

What is a common technique coupled with mass spectrometry for protein analysis?

Answer 8

Liquid chromatography (LC), in a technique known as LC-MS.

Question 9

What does LC-MS stand for?

Answer 9

Liquid Chromatography-Mass Spectrometry.

Question 10

Why is liquid chromatography often used in conjunction with mass spectrometry?

Answer 10

It helps to separate complex mixtures of proteins or other analytes before they are analyzed in the mass spectrometer.

Question 11

What is tandem mass spectrometry or MS/MS?

Answer 11

A technique where ions are selected based on their m/z ratio and then further fragmented and analyzed. It provides detailed structural information.

Question 12

How is a sample typically ionized for mass spectrometry in molecular biology?

Answer 12

Techniques like Electrospray Ionization (ESI) and Matrix-Assisted Laser Desorption/Ionization (MALDI) are commonly used.

Question 13

What is ESI and MALDI in the context of mass spectrometry?

Answer 13

ESI (Electrospray Ionization) and MALDI (Matrix-Assisted Laser Desorption/Ionization) are techniques used to ionize samples for mass spectrometry.

Question 14

What is a mass spectrum?

Answer 14

It’s a plot of the ion signal as a function of the m/z ratio. The mass spectrum represents the mass distribution of the sample.

Question 15

What is peptide mass fingerprinting?

Answer 15

It’s a method of protein identification where the masses of peptides from a protein digest are matched to theoretical masses from a protein database.

Question 16

What is the role of the matrix in MALDI?

Answer 16

The matrix absorbs the laser energy and assists in the desorption and ionization of the sample.

Question 17

What is a time-of-flight (TOF) analyzer?

Answer 17

A type of mass analyzer that separates ions by their time of flight through the analyzer - lighter ions arrive at the detector sooner than heavier ions.

Question 18

What is proteomics?

Answer 18

The large-scale study of proteins, often involving identification and quantification via mass spectrometry.

Question 19

How can mass spectrometry help in the study of post-translational modifications?

Answer 19

It can identify and locate modifications on proteins, such as phosphorylation, methylation or glycosylation.

Question 20

What is the role of a mass spectrometer detector?

Answer 20

It detects the separated ions and converts their abundance into an electrical signal that can be processed and analyzed.