Protein (Biology)

Proteins

Proteins are macromolecules. They are constructed from one or more unbranched chains of amino acids, which is polymers. Proteins are the most diverse group of biologically important substances and are often considered to be the central compound necessary for life. In fact, the translation from the Greek root word means “first place.”

Amino Acids

Amino acids bonded together by the dehydration synthesis. By continually adding amino acids, called peptides, two amino acids join together to form dipeptides; as more peptides join together, they form polypeptides. Proteins vary in length and complexity based on the number and type of amino acids that compose the chain. There are about 20 different amino acids, each with a different chemical structure and characteristics. For instance, some are polar, others are non-polar.

Protein Structure

The first level, or primary structure, is the linear sequence of amino acids that creates the peptide chain. In the secondary structure, hydrogen bonding between different amino acids creates a three-dimensional geometry like an alpha helix or pleated sheet. An alpha helix is simply a spiral or coiled molecule, whereas a pleated sheet looks like a ribbon with regular peaks and valleys as part of the fabric. The tertiary structure describes the overall shape of the protein. Most tertiary structures are either globular or fibrous. Generally, nonstructural proteins such as enzymes are globular, which means they look spherical. The enzyme amylase is a good example of a globular protein. Structural proteins are typically long and thin, and hence the name, fibrous.