The three-dimensional structure of proteinsThe covalent structure of a protein is made up of hundreds of individual bonds. Since free rotation is possible around many of these bonds, the protein can take a very large number of possible conformations. However, each protein is responsible for a particular chemical or structural function, meaning that each has a distinct three-dimensional configuration. By the early 1900s, many proteins were crystallized. Since the ordered set of molecules in a crystal can only form if all the molecular units are identical, the discovery that proteins can be crystallized proved that even the largest proteins have distinct chemical structures. This deduction has completely transformed the understanding of proteins and their respective functions. It is important to study how a series of amino acids in a polypeptide chain are translated into a three-dimensional protein structure. There are five general topics related to this process: the structure of a protein is determined by its amino acid sequence, the role of a protein depends on its unique structure, an isolated protein generally exists in a small number of stable forms , non-covalent interactions are the most important stabilizing forces in the structure of a protein, and there are structural models that help explain and understand the architecture of a protein. The conformation of a protein is the three-dimensional arrangement of its atoms. The feasible conformations of a protein include all structural states that can be achieved without breaking covalent bonds. A conformational change could occur, for example, by rotation around a single bond. Among the many possible conformations (the...... middle of paper ...... remain the same throughout the segment. A few types of secondary structures are particularly stable and are therefore widely present in proteins. The most important The secondary structures are the alpha-helix and beta conformations, as well as a structure called the beta turn. When a regular pattern cannot be determined or found, the secondary structure of the protein is naturally called undefined or even random coil. , the path of a polypeptide backbone is anything but random; it is generally unchanging and specific to the function and structure of that specific protein. The simplest arrangement a polypeptide chain can adopt is a helical structure, also. known as the alpha helix a particular structure can be described as the polypeptide backbone tightly wound around an imaginary axis with the R groups of the amino acid protruding outward..