Related Experiment Video
Updated: Aug 15, 2026

Measurement of Heme Synthesis Levels in Mammalian Cells
Published on: July 9, 2015
Heme-linked proton dissociation of carbon monoxide complexes of myoglobin and peroxidase
Abstract:
It was found from spectrophotometric titration and proton balance measurement that the pKa value of a heme-linked protonation group of horseradish ferro-peroxidase C (donor:H2O2 oxidoreductase, EC 1.11.1.7) shifted from 7.25 to 8.25 upon combination with CO. The spectrophotometric titration experiment with myoglobin also revealed the presence of a heme-linked protonation group, the pKa value being 5.57 in myoglobin and 5.67 in the CO-myoglobin complex. It was concluded that the distinct shift of the pKa value in the case of peroxidase was attributable to the presence of a hydrogen bond between the sixth ligand and the distal base. The difference in the strength of such hydrogen bonding between peroxidase and myoglobin was discussed.
More Related Videos
Related Concept Videos
Cofactors and Coenzymes
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Cofactors and Coenzymes
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
Electron Transport Chain: Complex III and IV
Hemoglobin
When all four heme groups are bound to oxygen, the resulting molecule is called oxyhemoglobin. As a result, arterial blood...
Oxygen Transport in the Blood
![Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F55858.jpg&w=3840&q=50)
