Читать книгу Bioinformatics and Medical Applications - Группа авторов - Страница 74

Proteins are formed by amino acids; they are the fundamental units of every living organism; they are transformed into tissues, muscles, skin, or nails, but they can also be converted into accelerators or retardants of chemical or physiological processes. Life could not be understood without them.

The first representation of a protein is a succession of amino acids; it is like placing one amino acid after another, this representation is called linear representation or sequence. Then, three representations take place in the three-dimensional space that are related to the form the amino acids settle.

When protein amino acids cluster, they take forms like alpha helices and beta sheets, this is called a secondary representation. When these small structures bind together, the protein has a tertiary representation. Finally, if the protein is so large that it is made up of two or more tertiary structures, then it is said to be a protein with a quaternary structure.

A protein may be made up of few amino acids or thousands of them; however, their number has nothing to do with the size it adopts but with its regulation. Suffice it to say that as an example the SARS-CoV-2 structural protein (Spike) has 1283aa and yet it only has few microns.

Note 3.1 Here, it is important to mention that viruses are formed by proteins, and although at the time being, it is still discussed whether they are living organisms or not, they are also formed by proteins.