What Makes One Protein Different From Another?

Protein Structure

• A protein's structure comes from what elements compose it. Proteins are complex organic molecules made up of smaller organic molecules known as amino acids. Twenty different amino acids exist in nature. A protein is made from a combination of between two and 100 amino acids. The chemical composition of the protein molecule determines the varieties of each protein's unique shape, folds and bends, like a string or ribbon.

Primary Protein Structure

• When chemists refer to a protein's primary structure, they are talking about which small organic molecules -- amino acid base pairs -- come together to make a chain that forms the protein. All 20 amino acids come from combinations of four base pairs, which are guanine, thyamine, cytosine and adenine. One way to determine which protein you are looking at is to look at the sequence of its base pairs.

Secondary Protein Structure

• The secondary structure of proteins describes how the protein folds to form either a helix shape, or a shape like a pleat. The hydrogen atoms on different parts of a protein's molecular structure interact and bond, which causes the protein to fold or twist in its own particular shape.

Tertiary Protein Structure

• Looking at the overall shape of a protein is another way to determine which protein it is. Chemists referring to the tertiary structure of a protein look at the shape, structure, and constituent base pairs as a three-dimensional form held together by ionic bonds, hydrogen bonds, and other weak intermolecular forces.

Protein Function

• Organic chemists categorize proteins by the functions they perform within the body. Proteins perform an array of tasks depending on which organ system they associate with. Some proteins, immunoglobulin or antibodies, function with the immune system and assist the body with neutralizing foreign agents that may cause harm or damage to the body. Myosin and actin are proteins deriving from the motor system of the body, which help our bodies turn the sugar and minerals in our food into our ability to move. Other functions of proteins are to regulate chemical reactions in our bodies, maintain the shape of our tissues and organs, send and receive signals from the nervous system, and store energy.