ABSTRACT
The primary structure of proteins depends on sequence of nucleotides at the genetic code. Proteins can be composed solely of an alpha helix or a beta sheet, but usually globular proteins are composed of a bundle of beta strands inside the molecule covered on their surface with alpha helices. The description of the dynamic state of protein molecules came from many sources, the most important were: experimental techniques, X-ray crystallography and computer simulations. Important to the understanding of physiology and especially pathology of some proteins is the knowledge of their evolutionary origin. The concept of the common origin of proteins may be important to the explanation of certain pathological disturbances. Recent biochemical and genetic data suggest that in eukaryotes covalent conjugation of ubiquitin to short-living intracellular proteins determines their selective degradation. Ubiquitin bound to the N-terminal ends of protein molecules does not designate these proteins for degradation.
