"The native structure of h[a]emoglobin (Hb) comprises of two α and two β subunits, each of which carries a h[a]eme group. There appear to be no previous studies that report the in-vitro folding and assembly of Hb from highly unfolded α and β globin in a 'one-pot' reaction. One difficulty that has to be overcome for studies of this kind is the tendency of Hb to aggregate during refolding. This work demonstrates that denaturation of Hb in 40% acetonitrile at pH 10.0 is reversible." (J Am Soc Mass Spectrum 2007, 18, 8-16)
-Haemoglobin, when subjected to 40% acetonitrile at pH 10.0, loses its quaternary structure, which means the ________.
A) four α and β polypeptides dissociate
B) peptide bonds between amino acids break
C) α and β polypeptides lose their 3-D structure
D) four α and β polypeptides dissociate, peptide bonds between amino acids, and α and β polypeptides lose their 3-D structure

Question

Quizplus · Accepted Answer

The quaternary structure of hemoglobin involves the assembly of its four subunits (two α and two β). When it loses this structure, the subunits dissociate, but the peptide bonds and the 3-D structure of individual polypeptides remain intact.

"The Native Structure of H[a]emoglobin (Hb) Comprises of Two α