Question

This is for a biochemistry class. Thanks

7. How is phenyl Isothiocyanate useful in determining protein structure? 8. The absorption coefficient of bovine immunoglobulin at 280 nm is 210,000 M cm What is the absorbance of a 0.1 mg ml solution across a 1-cm path? What percentage of the incident light is transmitted by this solution? (Hint: check question 3.4 in the textbook) 9. The relative electrophoretic mobilities of a 30-kDa protein and a 92 kDa protein used as standards on an SDS-polyacrylamide gel are 0.80 and 0.41, respectively. What is the apparent mass of a protein having a mobility of 0.62 on this gel? 10. A peptide digested with trypsin produced the following three fragments: C, ASFPK, and GGRWDGdK The same peptide digested with chymotrypsin produced the following three fragments: PKGGRW, DGKC and ASF What is the primary structure of the peptide?

Answer 1

7) Phenylisothiocyanate is used in Edmans degradation reaction. At first, it reacts with N terminal aminoacid under alkaline conditions and forms phenylthiocarbamoyl compound which is a cyclical derivate. Then, under acidic environment, the cyclical compound is extracted and removed as thiazolinone derivattive which in turn forms a stable compound phenylthiohydantoin derivative of amino acid which can be identified using electrophoresis or chromatography. Then, the entire process is repeated to find the next N terminal amino acid. By this method, phenyl isothiocyanate is used in determining protein structure.

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