What are some of weaknesses of BLASTP searching and Conserved Domain searching for protein annotation? Conserved Domain doesn't provide ALL the potential domains of a protein BLASTP cannot assign function to protein Conserved Domain lacks capability for complete functional annotation. Conserved Domain only gives a portion of the whole protein

4. Deducing quaternary structure via SDS-PAGE. SDS-PAGE is a convenient method for separating polypeptides solely on the basis of size. Small polypeptides travel faster than large ones; rate of migration through the gel is inversely proportional to the logarithm of molecular weight. The subunit structure of a multimeric protein often can be deduced using this technique in conjunction with a protein cross-linking agent. Cross-linking agents react with amino acid residues of two polypeptides that are in contact, thereby linking them by covalent bonds. After limited treatment with the reagent, so that some but not all subunits become cross-linked to their neighbors, the protein is subjected to SDS-PAGE and the molecular weights of the resulting proteins (bands) are estimated. The results of such experiments on two proteins (Protein A and Protein B) are shown below. What is the most likely subunit structure of each protein? Protein A SDS-PAGE cross-linking agent MW 105,000 70,000 35,000…

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A researcher has synthesized two peptides and needs to confirm whether the peptides were synthesized with the correct sequence using mass spectrometry. What is the sequence of the b4 and y7 ions for peptide GAMECHANGER?  The peptide SLISRAEFLAGVRVGV is digested with trypsin. Then the products of the digestion are subjected to ESI TOF-MS in positive ion mode with the peptides in a pH 2 solution. What peptide fragments will result and what are their m/z?