Protein was the first substance to be recognized as an essential part of health. Major structural parts of the body’s cells that are made of nitrogen-containing amino acids assembled in chains. About 20% of human body mass is protein.
The word protein was coined by the Dutch chemist Gerardus Mulder in 1838 and comes from the Greek word protos, meaning ‘of first importance’.
Structural components of the cell, antibodies, and many of the hormones are proteins but as much as 90% of cellular proteins are the enzymes upon which fundamental cellular function depends. They may be as many as 1000 different enzymes in a single cell.
The function of a dietary protein is to supply the nitrogen for the synthesis of a a variety of nitrogen-containing compounds such as heme, creatine, hexosamine, dispensable amino acids and to provide those amino acids that cannot be synthesized in adequate amounts.
Proteins catalyze virtually all chemical reactions in the body, regulate gene expression, comprise the major structural elements of all cells, regulate the immune system and form the major constituents of muscle.
Proteins are considered to be organic matter because they are made up of carbon, oxygen and hydrogen molecules. Proteins are unique that they are also made of up of a nitrogen molecules. The protein molecule is a polymer of amino acids joined in peptide linkages. Although the molecular weight is usually high, there is a vast range in both structure and complexity of protein molecules.
A peptide is a strand of amino acids. A strand of between 4 to 10 amino acids is called an oligopeptide.
When a person eats food proteins, whether from cereal, vegetables, beef, fish, or cheese. The body must first alter them by breaking them down into amino acids; only the can it rearrange them into specific human body proteins.
Hemoglobin for example is one of the proteins with quaternary structure, It consist of four globulin molecules held together by hydrogen bonds.
It has a molecular weight of about 64,500; myosin, a muscle protein is estimated to have a molecular weight of about 489,000.
Proteins and Amino Acid
