Bioinformatics assignment Example | Topics and Well Written Essays - 1000 words

Bioin coiffeics - Assignment Example taxs 1-7 are related to the material in Section B. Task 8 is to be found in Section C and uses the peptide sequence that was allocated to you. Marks are shown in parentheses. Task 1 (no marks) Write down the peptide sequence (near the start of section B) in single letter format (put a space between each letter) C G L V P V L A E N Y N K S Task 2 (8 marks) What do you conclude about the top seven matches for the peptide sequence? The results show that the matches are all peptide sequences which economy for transferrin protein, except for one match, ICA, which codes for an inhibitor of carbonic anhydrase in pigs. The sequence matches code for different forms of transferrin proteins in various species. For example the 14 amino pane of glass sequence is codes for serotransferrin in humans while it forms partition of the protein code for lactotransferrin in horse. This shows that the same peptide sequence codes for the same protein in different spe cies. Task 3 (1 + 1 marks) Write down a) The get along of amino acid residues 698 b) The relative molecular mass (Mr) 77,064 Task 4 (2 marks) What are the details against TITLE? Protein Chain A 329 residues Ligands CO3 338(A) Metal FE 339(A) Water ?138 Task 5 (1 + 2 + 1 + 4 marks) a) What is the number of cleavages for pepsin (at pH 1.3)? 214 b) Why is the pH quoted? The pH can take up the catalyst activity of an enzyme. Extreme pH can denature the active site of the enzyme. pH also gives an idea of the optimum temperature at which the enzyme is able to work. Changes in pH affect the follow ups of the enzyme. Therefore, at different pH, the hydrolytic action of the pepsin differs. Therefore, it is important to quote the pH. c) What is the number of cleavages for trypsin? 79 d) By reference to average peptide fragment lengths, which of the above both enzymes would be better for producing peptides for amino acid sequencing (and why)? Pepsin can mystify at a greater number of sit es than trypsin. This means that cleavage by pepsin can produce much shorter peptide fragments compared to cleavage by trypsin. For amino acid sequencing, usually if the peptide is less than 50 amino acid residues, there is no need to further cleave the peptide. The peptides which are 50 AA residues or less can be sequenced by a cyclic procedure, where the AA is primary labelled, cleaved and indentified the process is then repeated on the shortened fragment. However if the peptide is longer than 50 residues, there is a need to first shorten the protein chain before the cyclic procedure is carried out. This means that the enzyme which makes smaller fragments is able for sequencing in this case. Calculating the length of the peptide fragments Pepsin 698/214? 3 AA Trypsin 698/79?8 AA In this case, pepsin makes a fragment which is fitting to a single AA. This means that pepsin is more suitable. Task 6 (1 + 1 + 4 marks) a) What is the name of the amino acid residue to which carbohydra te is attached? Asparagine b) What is the position number of this amino acid in the proteins amino acid sequence? 432 c) How are sugars attached to proteins? Via glycosidic bonds Task 7 (1 + 1 + 1 + 4 marks) a) Number of disulphide tie 8 b) Number of strands 13 c) Number of helices 15 d) Why are disulphide bridges important for those proteins that have them? Disulphide bonds have an important role in the stability of proteins. They also help to meet about folding in the proteins. The disulphide bond lowers the entropy of the unfolded form of the protein, thus lowering its