Related Experiment Video
Updated: Aug 25, 2026

Intra-cardiac Side-Firing Light Catheter for Monitoring Cellular Metabolism using Transmural Absorbance Spectroscopy of Perfused Mammalian Hearts
Published on: May 12, 2019
Unusually weak oxygen binding, physical properties, partial sequence, autoxidation rate and a potential
J M Stewart1, J A Blakely, P A Karpowicz
1Biochemistry Programme, Department of Biology, Mount Allison University, Flemington Bldg, 63B York St. Sackville, NB, Canada E4L 1G7. jstewart@mta.ca
Abstract:
We purified myoglobin from beluga whale (Delphinapterus leucas) muscle (longissimus dorsi) with size exclusion and cation exchange chromatographies. The molecular mass was determined by mass spectrometry (17,081 Da) and the isoelectric pH (9.4) by capillary isoelectric focusing. The near-complete amino acid sequence was determined and a phylogeny indicated that beluga was in the same clad as Dall's and harbor porpoises. There were consensus motifs for a phosphorylation site on the protein surface with the most likely site at serine-117. This motif was common to all cetacean myoglobins examined. Two oxygen-binding studies at 37 degrees C indicated dissociation constants (20.5 and 23.6 microM) 5.7-6.6 times larger than horse myoglobin (3.6 microM). The autoxidation rate of beluga myoglobin at 37 degrees C, pH 7.2 was 0.218+/-0.028 h(-1), 1/3 larger than reported for myoglobin of terrestrial mammals. There was no clear sequence change to explain the difference in oxygen binding or autoxidation although substitutions (N66 and T67) in an invariant rich sequence (HGNTV) distal to the heme may play a role. Structural models based on the protein sequence and constructed on topologies of known templates (horse and sperm whale crystal structures) were not adequate to assess perturbation of the heme pocket.
More Related Videos
Related Concept Videos
Gene Families
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Globular and Fibrous Proteins
Globular proteins are also known as spheroproteins and typically are approximately round in shape. They contain a mix of amino acid types and contain differing sequences in their primary structures. Globular proteins have many different functions, such as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be...
Oxygen Transport in the Blood
Protein and Protein Structure
A protein's shape is critical to its function. For example, an enzyme can...
Protein Denaturation
Protein Families

