Answer to Question #328547 in Biochemistry for Andrew the god

Question

Study the polypeptide structuresequence of a β-strand shown below

b)Calculate the weight of the protein in KDa

Lys-Gly-Asp-Trp-Ser-Glu

a)Draw the chemical structure of the polypeptide. Indicate on the structure the

backbone and peptide bonds

c)Calculate the length of the protein.

Answer 1

To calculate the weight of the protein we should add together all the molecular weights of the amino acids present in the sequence and subtract the molecular weight of water for every bond created.( the average weight of amino acid is 110 Da and molecular weight of water is 18)

So we have 6 amino acids and 5 peptide bonds 

(6•110)-5•18=570 Da= 0,57 kDa weight of the protein

To calculate the length we should multiply number of amino acids by 0,36nm( this is the average length of amino acid)

6•0,36nm=2,16nm