... proteinaceous substances where ...
- the difference in structure between them is due to post-translational events (such as different glycosylation patterns) or different tertiary structures ...
Because the physiological activity of most proteins is closely linked to their three-dimensional architecture, specific terms are used to refer to different aspects of protein structure. The term primary structure denotes the precise linear sequence of amino acids that constitutes the polypeptide chain of the protein molecule. Automated techniques for amino-acid sequencing have made possible the determination of the primary structure of hundreds of proteins.
The physical interaction of sequential amino-acid subunits results in a so-called secondary structure, which often can either be a twisting of the polypeptide chain approximating a linear helix (-configuration), or a zigzag pattern (-configuration). Most globular proteins also undergo extensive folding of the chain into a complex three-dimensional geometry designated as tertiary structure.
