1. The molecular weight of a protein can be determined by SDS-PAGE or by sedimen
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Question
1. The molecular weight of a protein can be determined by SDS-PAGE or by sedimentation equilibrium. Which method would you use to determine the molecular weight of a protein containing four subunit, each consisting of two polypeptide chains cross-linked by two disulfide bridges? Explain your answer.
2. A) What treatments could you apply to the following hemoglobin fragment to determin the amino-terminal residue and to obtain two sets of peptides with overlaps so that the complete amino acid sequence can be established? B) Give the sequences of the peptids obtained.
a. VAl-Leu-Ser-Pro-Ala-Lys-Thr-Asn-Val-Lys-Ala-Ala-Trp-Gly-Lys-Val-Gly-Ala-His-Ala-Gly-Glu-Tyr-Gly-Ala-Glu-Ala-Thr-Glu
3. The production of a small acidic protein, Human Chorionic Gonadotropin, during pregnancy is the basis of most pregnancy test kits. What method makes the most sense for detecting a known protein like this?
Explanation / Answer
1.SDS PAGE can be used to determine the molecular weight, as we are not reducing the disulphide bonds in this case,hence we can get the weight of the entire protein as a whole i.e in the native state. 2] for sequencing we can use sangers method or edman degradation, to obtain overlapping fragments or peptides, we can use mass spectrometry,peaks will be obtained for fragments after proteolytic digestion. now it depends which enzyme u will use, enzymes used to cut after proline n-terminal,
3] use anti chorionic gonadotropin antibody to detect the presence of a known protein
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