Protein Folding

Protein Folding

Protein folding is the process by which a protein is folded and held together by several forms of molecular interactions into its native three-dimensional shape. All protein molecules are heterogeneous unbranched chains of amino acids which then fold into a specific three-dimensional shape of a functional protein. Amino acids interact with each other to produce a well-defined three-dimensional structure. The molecular interactions between amino acid include the thermodynamic stability of the complex, the hydrophobic interactions and the disulfide bonds formed in the proteins.

One of the most key factor in a proteins ability to fold is the thermodynamics of the structure. The thermodynamics are a main stabilizing force in which a protein will continue to fold and adjust until it is in the most stable state. The most stable form has the lowest energy conformation.

Hydrophobic interactions are the tendency of nonpolar side chain to interact with another hydrophobic amino acid. In contrast, amino acid with polar side chain tend to be located on the surface of the molecule in contact with the polar solvent.

Another type of interaction seen when the protein is folding is the disulfide linkages that form in the protein. A disulfide bond is covalent linkage formed from the sulfhydryl group (-SH) of each two cysteine residues to produce a cystine residue. A disulfide bond contributes to the stability of the three-dimensional shape of the protein molecule and prevents it from becoming denatured in the extracellular environment.

References

1. Garrett, R.H., and Grisham, C.M. Biochemistry fourth edition; Brooks/Cole. Australia, 2010.
2. Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walters P (2002). "The Shape and Structure of Proteins". Molecular Biology of the Cell; Fourth Edition. New York and London: Garland Science.