It is possible to distinguish different structural levels in the structure of proteins:
a) Primary Structure
b) Secondary Structure
c) Suprasecondary structure
d) Tertiary Structure
e) Quaternary Structure
(P-09) This structural level refers to the non covalent association of discrete polypeptide subunits into a multi subunit protein. (Not all proteins have this structural level)
(P-10) It can be defined as the sequence of amino acids in a polypeptide chain, read from the amino terminal amino acid to the carboxyl terminal amino acid.
(P-11) This structural level is not affected during the denaturation of proteins.
(P-12) In Sickle Cell anemia, the amino acid glutamic acid, in the position 6 of the beta chains of Hemoglobin is changed by valine. This disorder is an example of an alteration in this structural level
(P-13) Pr P c (normal protein) and Pr PSc (abnormal) Prions proteins are very similar proteins. Pr PSc, related with Creudtzfel-Jacob Disease, fatal insomnia and other human and animal diseases (as mad cow disease), can induce changes in the structure of Normal Pr Pc protein. One striking difference between both proteins, that share the same amino acid sequence, is the fact that Pr PSc shows high Beta strand content and low alpha-helix content, while Pr Pc shows high alpha-helix content and low beta strand content. Beta strand and alpha helix are types of this structural level