Abstract
Rainbow trout myoglobin (Mb) is characterized by an unusually low affinity for oxygen, having a P50 of 4.92±0.29mmHg at 25°C which is the highest ever reported for any vertebrate Mb at the same temperature (Helbo and Fago, (2011) Am. J. Physiol. Regul. Integr. Comp. Physiol. 300, R101-R108). In order to gain insight into the structural factors of the heme pocket that may be important determinants for this atypical oxygen affinity, we have carried out an electronic absorption and resonance Raman characterization of the ferric and ferrous protein with and without exogenous ligands (O2, CO, F−) and compared the results with those of other Mbs. While the ν(Fe–His) stretch appears at a frequency similar to other vertebrate Mbs, the resonance Raman frequencies of the Fe-ligand stretching modes reveal significant variations in the interaction of iron-bound ligands with distal residues. In particular, the spectroscopic characterization highlights two exceptional properties of rainbow trout Mb, a significantly higher level of reversed heme and reduced hydrogen bonding interactions between ligands and the distal HisE7 residue compared with other Mbs. The weakening of the hydrogen bond interaction is proposed to be the primary cause of the significantly reduced oxygen affinity.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
