Question

13. Heme is an achiral molecule that binds to the protein myoglobin. However, a 30 micromolar solution of myoglobin (containing heme) in 5 mM sodium phosphate buffer at pH 7 exhibits a positive circular dichroism signal near 400 nm (where heme absorbs). Since chirality is a requirement for circular dichroism, what is responsible for the CD signal?

Answer 1

The near-UV CD range (>250 nm) of proteins delivers info on the define configuration. The indications found within the 250–300 nm section are because of the engagement, dipole alignment and also the environment of the encircling atmosphere of the essential amino acid, tyrosine, aminoalkanoic acid (or S-S disulfide associations) and essential amino acids. In contrast to far-UV CD, the near-UV CD variation can't be allotted to any specific 3D configuration. Relatively, near-UV CD varieties offer essential info on the character of the prosthetic teams in proteins, e.g., the pigment teams in hemoprotein and cytochrome.