The linear sequence of amino acids in a small protein is sufficient to code for its folding into its functional tertiary structure. However, scientists have not yet managed to unscramble this code, and as a consequence the folded structure of a protein cannot be predicted from its known sequence of amino acids. The cracking of this code is therefore one of the great challenges of contemporary science and is the subject of much current research activity.
We plan to make a contribution to the solution of this problem by studying the foldings of the proteins ubiquitin and ferredoxin. The former is a protein which is found in every cell, and is physiologically important in the destruction of defective proteins. The latter is involved in the process of photosynthesis.
Both the chosen proteins are believed to be excellent models because as proteins go, they are relatively small and simple. The N-terminus of each of these proteins is involved in the formation of a loop structure, which is commonly described as a B-hairpin. These hairpin loops, each of about 17 amino acids, are to be synthesised by solid phase peptide synthesis, and the technique of proton nuclear magnetic resonance then used to determine if these fragments of the whole proteins take up structures analogous to those found in the proteins themselves.
Synthesis of modified hairpins, will allow us to probe those features which are important in the determination of loop structures.