Protein structure

The building blocks of life constitute carbohydrates, fats, nucleic acids and protein. About 45 percent of the human body is composed of protein. Protein is a vital macromolecule and without it, the human body would not be able to regulate, function or repair itself. Proteins are involved in the most basic functions of life. Proteins are molecules in the cells of the body and are involved in all cellular functions.

The different types of proteins include antibodies, which are distinctive proteins that protect the body from foreign invaders, called antigens. These proteins immobilize the antigens so that the white blood cells can destroy them. Contractile proteins are involved in bodily movement. Examples of contractile proteins are myosin and actin. They regulate the contraction and movement of the muscles.  Enzymes are proteins which aid in biochemical reactions. They are also known as catalysts and examples include pepsin and lactase.  These catalysts work by initiating a reaction with another protein and themselves and in the process change the other molecule in some manner. The enzymes themselves remain unchanged. Enzymes are known to be part of about 4,000 reactions taking place within the body. Lactase is involved in the breakdown of the lactose contained in milk, while pepsin functions in the stomach and regulates the breakdown of proteins contained in food. Enzymes play an important role in the reactions that occur during digestion, metabolism and DNA replication. Hormonal proteins are referred to as messenger proteins and these help in coordinating certain activities of the body. Examples include oxytocin and insulin. Insulin controls the metabolism of sugar by regulating the concentration of sugar in the blood. Oxytocin promotes contractions in women during childbirth. Structural proteins include keratin which strengthens the hair, and elastin which strengthens the connective tissues in the body such as ligaments and tendons. Storage proteins are used for storing amino acids. Examples include casein and ovalbumin. Transport proteins help to carry molecules from place to place within the body. These include hemoglobin and cytochromes. Hemoglobin is involved in the binding of iron molecules and transporting them from the lungs to the other parts of the body through the blood stream.

Protein Structure Database -

Protein structure can be divided into primary, secondary, ternary and quaternary. Primary protein structure is defined by the protein or amino acid sequence in the polypeptide chain. Secondary protein structure refers to the specific geometric shape resulting from the intermolecular and intramolecular hydrogen bonding of the amide groups. Ternary structure completely defines the three dimensional structural organization of the molecule. Quaternary structure is the defined structure resulting from the interaction between different protein molecules. Protein structure prediction is the prediction of the tertiary structure of a protein molecule from its primary structure. It is one of the most important tasks carried out in the fields of medicine, especially biotechnology and drug design. A protein structure database consists of the different protein structures that have been experimentally determined. The aim of these databases is to explain and organize the protein structure and provide access to the experimental data for the biological community. The study of protein structure is constantly breaking new ground and this allows for breakthroughs in the treatment of many diseases.