Biochemistry & Biophysics: Macromolecules, Bonds, and Interactions

Life

Composed almost entirely of molecules made from six types of atoms.

Atoms

Form molecules by making strong covalent bonds that have specific lengths and geometry.

Structures of macromolecules

Determine their functions.

Biological macromolecules

Long chains containing many freely-rotating single bonds, allowing tremendous conformational flexibility.

Non-covalent interactions

Four types cause macromolecules to fold into specific conformations.

Reversible binding

The same four non-covalent interactions allow macromolecules to reversibly bind specific substrates.

Chemical bonds

About 10-10 M long=1 Ångstrom.

Single bonds

Allow free rotation.

Double bonds

Do not allow free rotation.

Ionic bonds

Result from attraction between opposite charges and are nondirectional.

Ionized carboxyl group

-COO-.

Hydrogen bonds

Result when a partially positive charged H bond donor shares a proton with a partially negatively charged H bond acceptor; they are directional and have a specific length.

Hydrophobic interaction

Within a macromolecule, it is driven by maximizing H bonding of the surrounding water.

van der Waals interactions

Occur between nonpolar surfaces due to synchronized transient electric dipoles.

Single bond

A type of chemical bond that allows free rotation.

Double bond

A type of chemical bond that does not allow free rotation.

Bond rotation

The ability of a bond to rotate, applicable to single bonds.

Space-filling model

A model that represents the spatial arrangement of atoms in a molecule.

Conformation

The three-dimensional shape of a macromolecule.

Ångstrom

A unit of length equal to 10^-10 meters.

Carboxyl group

A functional group characterized by -COOH.

Amine group

A functional group characterized by -NH2.

Hydrophobic

Describes molecules that do not interact favorably with water.

Hydrophilic

Describes molecules that interact favorably with water.

Polar

Describes molecules with a distribution of electrical charge leading to partial positive and negative regions.

Non-polar

Describes molecules that do not have distinct positive and negative regions.

Substrate

The substance on which an enzyme acts.