Folding of the polypeptide chain occurs via an interaction between the R groups of amino acids. This tends to be globular in shape and contains a binding site for the protein action. Tertiary protein structure is the folding of the polypeptide chain into a unique 3D structure. The sheets can be in parallel or antiparallel. Beta-pleated sheet – formed by hydrogen bonds between the carboxyl group of one amino acid on one sheet and the hydrogen molecule of an amino acid on another sheet.The strong bonds and stability of this structure give it a strong tensile strength, which allows it to form the shape seen in DNA. Alpha-helix – a coil formed by hydrogen bonds between the carbonyl group and the amino group of different amino acids.The most common examples are the alpha-helix and beta-pleated sheets. Secondary protein structure is the repetitive folding of polypeptide chains by hydrogen bonds between the hydroxyl (OH) group and the hydrogen molecule of the adjacent amino acid, leading to the unique shape of the protein. Any mutation in this amino acid sequence can affect protein folding, leading to problems with the protein’s function. These bonds form between the N terminal and C terminal of amino acids and are highly resistant to heat or chemicals. Primary protein structure is when amino acids bound are together via covalent peptide bonds to form a polypeptide chain. Protein structure can be divided into four main categories depending on the level of complexity. 12 of these can be synthesised in the body, while the other 9 must be consumed in the diet and are termed essential amino acids.ĭiagram showing the basic structure of an amino acid. There are a total of 21 amino acid types based on their different R groups. The R group gives the amino acid specific features according to its polarity and charge, which then affect the chemical and biological properties of the protein. Their structure consists of three main groups as seen in figure 1, namely the amino group or N terminus, the carboxyl group or C terminus, and the R group which contains the functional component of the amino acid. Depending on the structure of the protein they will have different functions within the body, including structural, regulatory, contractile and protective roles.Īmino acids are the basic building blocks of proteins.

Proteins are made up of amino acids which undergo various stages of folding to form their shape and structure.

Download free protein structure