430-530-Lec 4 Protein Structures 2025

What are the four levels of protein structure?

Primary, Secondary, Tertiary, and Quaternary.

What stabilizes the secondary structure of proteins?

Hydrogen bonds.

What are the two common types of secondary structures found in proteins?

α-helices and β-sheets.

What is the primary structure of a protein?

The linear sequence of amino acids.

What role do disulfide bridges play in protein structure?

They are covalent bonds that stabilize the tertiary structure of proteins.

What dictates the tertiary structure of a protein?

The arrangement of secondary structures and the positions of the side chains.

What types of interactions contribute to protein conformation?

Hydrophobic effects, hydrogen bonds, ionic bonds, van der Waals forces, and disulfide bridges.

What is an example of a fibrous protein?

Collagen.

What type of protein is hemoglobin classified as?

A globular protein.

What is the function of motifs in proteins?

are combinations of secondary structures that can bring distant portions of primary structure together.

What is the definition of protein denaturation?

The unfolding of a protein, usually leading to loss of biological activity.

How does heat affect protein structure?

It can disrupt weak bonds and secondary structures.

What is the difference between protein denaturation and protein reduction?

Denaturation involves unfolding and loss of structure; reduction specifically breaks disulfide bonds.

How is the structure of myoglobin described?

It is a single polypeptide with multiple α-helices.

What is the significance of hydrophobic amino acids in protein structure?

They tend to cluster in the interior of the protein, minimizing interactions with water.

What kind of interactions occur in the quaternary structure of proteins?

Interactions between two or more polypeptides, which can be homo- or heteropolymers.

What are the effects of pH on proteins?

Changes the ionization state of amino acid R-groups, potentially disrupting secondary structures.

What amino acids are commonly found in loops and turns of protein structures?

Glycines and Prolines.

What is a major characteristic of globular proteins?

They have a compact and rounded shape and serve functional roles.