The word protein comes from the Greek ‘proteios’ which means ‘of the first rank or importance’.
Nearly half of the dry weight of a typical animal cell is protein. 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.
Protein are essential components of muscle, skin, cell membranes, blood, hormones, antibodies, enzymes and genetic material and almost all other body tissues and components.
The protein molecule is a polymer of amino acids joined in peptide linkages. Nitrogen molecules are combined with hydrogen molecules to make what is called an amino group.
Although the molecular weight is usually high, there is a vast range in both structure and complexity of protein molecules.
Hemoglobin for example, has a molecular weight of about 64,500; myosin, a muscle protein is estimated to have a molecular weight of about 489,000.
On the average, about 20 different amino acids occur in most proteins, the amino acids present, their position in the molecule, and the spatial arrangement of the molecule all determine the proteins and characteristics of the proteins. In turn the function of a protein depends, in large measure, on its structure.
Proteins play a critical role in virtually every physiological and biochemical process in the body.
Protein serves as cell communicators through the action of neurotransmitters. They are also essential for blood clotting, immune system development and formation of milk during lactation.
Proteins and amino acids
