kvaternaarstruktuuride

Kvaternaarstruktuuride refer to the arrangement of multiple polypeptide subunits within a protein. This level of protein organization describes how individual protein chains, known as subunits, associate with each other to form a functional, multi-subunit complex. The forces that hold these subunits together are typically non-covalent, including hydrogen bonds, ionic interactions, hydrophobic interactions, and van der Waals forces. Some quaternary structures are also stabilized by disulfide bonds between subunits. Not all proteins exhibit quaternary structure; proteins composed of a single polypeptide chain do not have this level of organization. The specific spatial arrangement of these subunits is crucial for the protein's overall shape, stability, and biological function. Examples of proteins with quaternary structures include hemoglobin, which consists of four globin subunits, and antibodies, which are typically composed of two heavy and two light chains. The assembly and disassembly of these quaternary structures can be a regulated process, playing a role in signal transduction and cellular responses.