Proteins

Primary Structure

The sequence of amino acids in a polypeptide chain determined by the DNA of the gene that encodes the protein

Secondary Structure

Local folded structures that form within a polypeptide due to interactions between atoms of the backbone Ex. alpha helix and beta pleated sheet (hydrogen bonds)

Alpha helix

When the carbonyl of one amino acid is hydrogen-bonded to the amino H of an amino acid

Beta pleated sheet

When two or more segments of a polypeptide chain line up next to each other, forming a sheet-like structure held together by hydrogen bonds between carbonyl and amino groups, while R groups extend above and below the plane of the sheet. (Tryptophan, tyrosine, phenylalanine)

“Helix Breaker”

Proline

Tertiary Structure

Overall three-dimensional structure (Non-covalent bonds, hydrophobic interactions, disulfide bonds)

Quaternary Structure

Proteins made up of multiple polypeptide chains (subunits)

Denaturation

A protein that loses its higher-order structure but keeps the same primary sequence (usually non-functional)

Conformational Entropy

protein folding resulting in a more ordered structure

Solvent Entropy

Hydrophobic side chains cluster together in the interior of the protein, water molecules are released into the bulk solvent, increasing the entropy of the surrounding water molecules.

Chaperones

Stabilize proteins, prevent aggregation, and provide an optimal enviornment for protein folding

Molecular Chaperones

Bind to nascent or partially folded polypeptides preventing improper interactions

Chaperonins

Cylindrical complexes that provide a protected enviornment for protein folding