Multimeric proteins with 4 identical subunits need which procedure prior to edman degradation ?
Answers
Answer:
Frederic Sanger first time achieved complete sequence of protein (bovine insulin) in
1953. For his work, he was awarded the Nobel Prize of Chemistry in (1958).
Protein sequencing refers to the techniques employed to determine the amino acid
sequence of a protein. There are several applications of protein sequencing, which are:-
a) Identification of the protein family to which a particular protein belongs and
finding the evolutionary history of that protein. Function prediction.
b) Prediction of the cellular localization of the protein based on its target sequence
(sequence of amino acids at the N terminal end of the protein which determines
the location of the protein inside the cell).
c) Prediction of the sequence of the gene encoding the particular protein.
d) Discovering the structure and function of a protein through various computational
methods and experimental methods.
Till date several methods have been utilized for protein sequencing. Two main methods
include Edman degradation and Mass Spectrometry. Protein sequence can also be
generated from the DNA/mRNA sequence that codes for the protein, which has been
explained in details in the recombinant DNA section. Here, we have discussed the most
important methods used for protein sequencing and the pros and cons of each method.
Edman degradation
Before sequncing procss is initiated, it is necessary to break all non-covalent interation by
denaturants (like high concentration of urea or GuHCl). This process will also separate
subunits, incase of oligomeric proteins. Ocassionally, subunits of a oligomeric protein are
connected by covalent interations. In that case special treatments are required to separate
subunits. The protein is treated with Edman’s reagent (phenyl isothiocyanate) which
reacts with the N-terminal amino acid and under mild acidic condition forms a cyclic