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PROTEIN FOLDINGProteins | Protein Structure | Protein folding | Movies All the information for synthesizing the primary structure of a protein encoded in the genetic material of the chromosomes, which is a double-stranded DNA in humans. A specific region of DNA or RNA codes for the primary structure of every protein that is synthesized are called genes. The first step in expressing the information in a gene is transcription of the nucleotide sequence into a complete messenger RNA (mRNA). mRNA molecules are translated into polypeptide chains in the cytoplasm by a complex apparatus of ribosomes.
Initially proteins are long extended molecules. However, they soon begin to fold because of many different type of forces acting upon them. In molecular modeling these forces are computed to simulate the folding of proteins. Proteins do not operate in vacuum but in aqueous solution. Water is a polar molecule. Generally speaking polar substances like aqueous solutions (Hydrophilic) and non-polar substances (hydrophobic) try to stay away from water, (due to energy and entropy considerations). So in the folding process the main driving force is for the hydrophobic portions of the protein chain to fold away from the outside water environment.
A) The folding of the polypeptide chain typically creates
a crevice or cavity on the protein surface. This crevice contains a set
of amino acid side chains disposed in such a way that they can make noncovalent
bonds only with certain ligands. (B) Close-up view of an actual binding
site showing the hydrogen bonds and ionic interactions formed between
a protein and its ligand (in this example, cyclic AMP is the bound ligand).
NEXTSee also: http://folding.stanford.edu/science.html Author: Tug Sezen Reference:Thomas E. Creighton (1993); Proteins; Freeman.
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