2BC3 Midterm

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Questions and Answers

Which of the following is correct about Edman degradation?

Treatment of protein at pH = 3 with PITC

Treatment with anhydrous acid results in cleavage of the C-terminal residue.

Edman degradation is required to determine the sequence of protein. (correct)

All of the above.

Which of the following statement is correct about fibrous proteins?

Fibrous proteins have 3º structure

Fibrous proteins are soluble

Fibrous proteins only have 2º structure (correct)

Fibrous proteins carry out metabolic functions

Which of the following statement is NOT correct about Loops?

Loops contribute to secondary structure

Loops can be quite long and “disordered”

Loops are held together by hydrogen bonding (correct)

Loops often contain hydrophilic residues

Which of the following is Globular protein?

Hemoglobin Signup and view all the answers

Which of the following is correct about β-Strands and β-Sheets?

All of the above Signup and view all the answers

The rise, pitch and the number of residues per turn of α-helix are

0.15 nm; 0.54 nm and 3.6 Signup and view all the answers

In α-helix, C=O hydrogen-bonded to each ____ H-N on backbone

the 4th Signup and view all the answers

Which of the following chromatography should be used to separate proteins on the charge?

Ion exchange chromatography Signup and view all the answers

Which of the following interaction maintains the protein secondary structure?

hydrogen bonding Signup and view all the answers

Which of the following is correct about turns?

Turns consist of up to 5 residues that induce an abrupt change in direction Signup and view all the answers

What is the mobile phase for size exclusion chromatography?

Water Signup and view all the answers

Which of the following residues is the most common in α-Helices?

alanines Signup and view all the answers

Which of the following is the subtype(s) of Mass spectrometry according to the ion source?

Both A and B Signup and view all the answers

SDS-PAGE is separating molecules according to_______.

mass Signup and view all the answers

During size exclusion (gel filtration) chromatography, __________ proteins are eluted in the earlier fraction

smaller Signup and view all the answers

Which of the following statement is correct about domains?

Discrete, independently folded regions; typically perform a specific function Signup and view all the answers

Which of the following solution will disrupt the hydrogen bonding in tertiary structure?

all of the above Signup and view all the answers

Which of the following is correct about Lectin Affinity Chromatography?

All of the above Signup and view all the answers

Which of the following statement is correct about SDS-PAGE?

Denaturing gel electrophoresis using the detergent Signup and view all the answers

Study Notes

Protein Structure and Chromatography

Edman degradation is a method to determine the N-terminal amino acid of a protein.
Fibrous proteins are composed of long, thin molecules and are often involved in structural or mechanical roles.
Loops are regions of protein structures that do not form α-helices or β-sheets and are often found on the surface of proteins.
Globular proteins are compact, roughly spherical molecules and are often involved in metabolic processes.

Protein Secondary Structure

β-Strands are extended protein structures that are often found in β-sheets, which are composed of multiple β-strands held together by hydrogen bonds.
α-Helices are spiral-shaped protein structures that are stabilized by hydrogen bonds between the C=O and H-N groups of the backbone, with 3.6 amino acids per turn.

Chromatography

Ion-exchange chromatography is used to separate proteins based on their charge.
Hydrogen bonds, ionic bonds, disulfide bonds, and hydrophobic interactions maintain protein secondary structure.
Size exclusion chromatography uses a mobile phase of buffer and separates molecules based on their size.

Protein Analysis

Turns are a type of non-repetitive secondary structure and are often involved in protein-protein interactions.
Glutamic acid is the most common residue found in α-helices.
Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) are subtypes of mass spectrometry.
SDS-PAGE separates molecules based on their size.

Protein Interactions and Purification

Domains are independently folded regions of a protein that are often involved in specific functions.
Urea is a solution that can disrupt the hydrogen bonding in tertiary structure.
Lectin affinity chromatography is a type of affinity chromatography that uses lectins to purify proteins based on their carbohydrate content.
In size exclusion chromatography, larger proteins are eluted in the earlier fraction.