Question

"The native structure of hemoglobin (Hb) comprises of two α and two β subunits, each of which carries a heme 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) Hemoglobin, when subjected to 40% acetonitrile at pH 10.0, loses its quaternary structure, which means the ________.

Answer 1

Answer: Three-dimensional structure/folding of the subunits is lost.

Explanation: Proteins can be categorized in 4 by the type of structure they have.

The Primary Structure is based on the plain sequence order of amino acids.

The Secondary Structure depends on the hydrogen bonds that amino acids form (α-helix or β-sheets)

The Tertiary Structure is based on the three-dimensional foldings that a single protein (monomeric protein) or polypeptide chain can acquire.

The Quaternary Structure is the one that a group of monomeric proteins or a multimer protein can acquire, by adding two or more subunits.

In this case, it means that the 4 subunits and the heme group that form Hemoglobin were disaggregated or denaturalized in 40% acetonitrile at pH 10.0