Heme proteins perform a large array of biological functions, with the heme group bound non-covalently or covalently. To probe the stabilization role of conserved tyrosine residue in the secondary sphere of heme site in heme proteins, we herein used cytochrome b(5) (Cyt b(5)) as a model protein, and mutated Tyr30 to Phe or His by removal of Tyr30 associated H-bond network and hydrophobic interaction. We performed thermal-induced unfolding studies for the two mutants, Y30F Cyt b(5) and Y30H Cyt b(5), as monitored by both UV-Vis and CD spectroscopy, as well as heme transfer studies from these pro...
