Biochemistry - Amino Acids and Protein Structure

Vocabulary-style flashcards covering the overview of proteins, the structure of amino acids, and the properties of nonpolar side chains based on the provided biochemistry lecture notes.

Proteins

The most abundant and functionally diverse molecules in living systems, consisting of linear polymers of amino acids.

Enzymes and polypeptide hormones

Molecules that direct and regulate metabolism in the body.

Contractile proteins

Proteins in muscle that permit movement.

Collagen

A protein that forms a framework for the deposition of calcium phosphate crystals in bone, acting like steel cables in reinforced concrete.

Hemoglobin and plasma albumin

Proteins in the bloodstream that shuttle molecules essential to life.

Immunoglobulins

Proteins that fight infectious bacteria and viruses.

20

The number of amino acids commonly found as constituents of mammalian proteins and coded for by DNA.

Secondary amino group

The unique structural feature of proline, which distinguishes it from the primary amino groups found in other common amino acids.

̑̑\alphȃ̑-carbon atom

The central atom to which the carboxyl group, primary amino group, and distinctive side chain (R-group) are bonded in an amino acid.

Physiologic pH

Approximately $pH\,7.4$, at which the carboxyl group is dissociated into a carboxylate ion ($-COO^-$) and the amino group is protonated ($-NH_3^+$).

Peptide linkage

The chemical connection through which carboxyl and amino groups are combined in proteins, generally making them unavailable for chemical reaction except for hydrogen bond formation.

Nonpolar side chains

Side chains with an even distribution of electrons that do not gain or lose protons or participate in hydrogen or ionic bonds.

Hydrophobic interactions

Interactions promoted by the ̑̑oily̑̑ or lipid-like properties of nonpolar side chains.

Interior of the protein

The location where side chains of nonpolar amino acids tend to cluster when the protein is in an aqueous solution.

Glycine $pK_1$

The dissociation constant for the carboxyl group of glycine, valued at $2.3$.

Glycine $pK_2$

The dissociation constant for the amino group of glycine, valued at $9.6$.

Polar side chains

Side chains that have an uneven distribution of electrons, such as those found in acids and bases.