Protein Structure and Function Flashcards

A set of vocabulary flashcards based on lecture notes covering protein structure levels, functional domains, folding, and disease associations.

Polypeptide

A string of amino acids linked together to form a protein.

Peptide backbone

The chain of repeating atoms in a polypeptide whose hydrogen bonding interactions are critical for protein folding.

Side chain (R group)

The variable chemical group attached to the amino acid backbone that determines the specific properties and functional characteristics of the amino acid.

Peptide bond

A covalent bond formed through a condensation reaction attaching the carboxyl group of one amino acid to the amino group of another.

Primary structure

The specific linear sequence of amino acids in a polypeptide chain, running from the amino terminus (N-terminus) to the carboxyl terminus (C-terminus).

Sickle Cell Disease

A disease used to illustrate the critical importance of primary structure, demonstrating that even a single change in an amino acid sequence can have severe consequences.

Secondary structure

Regular, local protein folding resulting from hydrogen bonding interactions within the polypeptide backbone, including \begin{matrix} \text{\textalpha-helices} \text{ and } \text{\textbeta-pleated sheets} \begin{end{matrix} structures.

\text{\textalpha-helix}

A secondary protein structure where the polypeptide backbone twists into a spiral with outward-pointing side chains, stabilized by hydrogen bonds between the N-H and C=O groups at every 4th amino acid.

\text{\textbeta-pleated sheet}

A secondary protein structure formed by hydrogen bonding between separate areas of a polypeptide, folding the backbone into a zig-zag plane with side chains projecting above and below.

Tertiary structure

The complete three-dimensional folding structure of a single polypeptide chain, incorporating \text{\textalpha-helices}, \text{\textbeta-sheets}, loops, and random coils to create distinct functional domains.

Catabolite activator protein (CAP)

A bacterial protein with two domains: a small domain that binds DNA and a large domain that binds cAMP to trigger conformational changes necessary for gene expression.

Ligand

A molecule that binds non-covalently to specific amino acid side chains at a protein's binding site, inducing a conformational change that activates the protein.

Quaternary structure

The functional assembly formed by the association of two or more identical or non-identical polypeptide chains (subunits).

Globular proteins

A structural class of quaternary proteins characterized by compact, rounded shapes, such as hemoglobin which contains 4 globular subunits.

Fibrous proteins

A structural class of quaternary proteins consisting of extended strand-like structures, such as collagen which is made of 3 supercoiled helices.

Hydrophobic core region

An interior area of a folded protein in an aqueous environment where nonpolar (hydrophobic) side chains gather to stay away from water.

Protein denaturation

The loss of a protein's natural tertiary and secondary structure and corresponding biological activity due to unfolding.

Cystic Fibrosis (CF)

A disease caused by a misfolded mutant transport protein that cannot function properly.

Alzheimer's Disease

A neurodegenerative condition where misfolded amyloid protein forms large, insoluble fibers that lead to nerve cell death.

Mad Cow Disease (CJD)

A fatal neurodegenerative disease caused by incorrectly folded prion proteins that aggregate and damage nerve cells.