Design of a five-coordinate heme protein maquette: a spectroscopic model of deoxymyoglobin.
The substitution of 1-methyl-l-histidine for the histidine heme ligands in a de novo designed four-alpha-helix bundle scaffold results in conversion of a six-coordinate cytochrome maquette into a self-assembled five-coordinate mono-(1-methyl-histidine)-ligated heme as an initial maquette for the dioxygen carrier protein myoglobin. UV-vis, magnetic circular dichroism, and resonance Raman spectroscopies demonstrate the presence of five-coordinate mono-(1-methyl-histidine) ligated ferrous heme spectroscopically similar to deoxymyoglobin. Thermodynamic analysis of the ferric and ferrous heme dissociation constants indicates greater destabilization of the ferric state than the ferrous state. The ferrous heme protein reacts with carbon monoxide to form a (1-methyl-histidine)-Fe(II)(heme)-CO complex; however, reaction with dioxygen leads to autoxidation and ferric heme dissociation. These results indicate that negative protein design can be used to generate a five-coordinate heme within a maquette scaffold.
Zhuang
Jinyou
J
Department of Chemistry, Columbia University, New York, New York 10027, USA.
Amoroso
Jennifer H
JH
Kinloch
Ryan
R
Dawson
John H
JH
Baldwin
Michael J
MJ
Gibney
Brian R
BR
D002248:Carbon Monoxide / Q000737:chemistry; D002942:Circular Dichroism; D006420:Hemeproteins / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008762:Methylhistidines / Q000737:chemistry; D008958:Models, Molecular; D009211:Myoglobin / Q000031:analogs & derivatives* / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D013816:Thermodynamics
D006420:Hemeproteins; D008762:Methylhistidines; D009211:Myoglobin; C055547:deoxymyoglobin; C028120:1-methylhistidine; D006639:Histidine; D002248:Carbon Monoxide; D007501:Iron