Map sapling learning oligomeric protein has a molecular weight of 343000. A 780
ID: 875491 • Letter: M
Question
Map sapling learning oligomeric protein has a molecular weight of 343000. A 780 mg sample was treated with an excess of I-Tluoro-2,4-dinitrobenzene (Sanger's reagent) until the reaction was complete. Next the peptide bonds were hydrolyzed by heating with Concentrated HCI. The product of the complete hydrolysis contained 2.0 mg of the compound shown below, and no other 2,4-dinitrophenyl derivatives of the a-amino groups of other amino acids could be found. NO2 How many polypeptide chains are in this protein? (Enter your answer as a whole number). O2N NH-C-COOH HC-CH Number CH CHExplanation / Answer
The number of polypeptide chain the the structure will be as follows.
780 mg (0.780 g) of sample gave = 2.0 mg (0.002 g) of the hydrolyzed product.
The mass of amino acid in 1 mole of hydrolyzed product = 1 mole
or,
297 g of hydrolyzed product contains 131 g of amino acid
i.e. 2.0 mg (0.002 g) will have = 0.002 x 131 / 297
= 0.0009 g
Thus 0.780 g sample has 0.0009 g of amino acid.
thus,
343000 g of oligomer will have = 343000 x 0.0009 / 0.780
= 396 chains of polypeptide chains in the protein
thus, the number of polypeptide chains in the protein is 396.