Proteins

From ArticleWorld

Proteins are complex, large compounds that are made up of amino acids connected by peptide bonds. They are vital to living things as they play important roles in the structure and function of cells. Some roles played by proteins include as catalyst in the form of enzymes, as structural proteins in the cytoskeleton and in the immune response. Proteins are synthesized based on a code stored in the genetic material of organisms. This is done by the processes of translation and transcription. Some amino acids necessary for protein synthesis but not synthesized by the organism are found in protein taken in by the diet and broken down into amino acids.

Structure

There are about 2o amino acids that are utilized in the synthesis of proteins. Genes are decoded and transcribed into RNA which is then modified into mRNA. This then undergoes translation into proteins. Proteins fold into a native state which is a 3D structure. There are four protein structures identified. The first is the primary structure which is basically the amino acid chain. The secondary structure is subject to hydrogen bonding and the tertiary structure is formed by hydrophobic interactions in addition to hydrogen bonds, disulfide bonds and ionic interactions. The quaternary structure results from the interaction of more than one protein chain and forms a protein complex.

Functions

Proteins are important to almost all the functions carried out by cells. They control almost all the molecular processes and regulate cell function. Some important functions that proteins carry out include in the catalysis of reactions. In this role they make up enzymes which catalyze metabolic reactions that may not occur otherwise in a manner able to sustain life. They also act as the structural proteins tubulin and collagen. Some proteins are also important hormones used in the homeostatic maintenance of organisms. In the immune system they make up defensive proteins such as antibodies which fight toxins and viruses. They also have nutritional value in the diet s not all amino acids required are synthesized by the body. Deficiencies in protein can result in problems such as fatigue, hair loss, muscle loss and many others. Protein deficiency in an extreme case, such as famine, can result in death. Some problems can arise if too much protein is consumed and these include an over-reactive immune system as well as liver dysfunction and bone loss.