Myoglobin evolution

Many examples of recurring domain or motif structures are available, and these reveal that protein tertiary structure is more reliably conserved than primary sequence. The comparison of protein structures can thus provide much information about evolution. Proteins with significant primary sequence similarity, and/or with demonstrably similar structure and function, are said to be in the same protein family. A strong evolutionary relationship is usually evident within a protein family. For example, the globin family has many different proteins with both structural and sequence similarity to myoglobin (as seen in the proteins used as examples in Box 4-4 and again in the next chapter). Two or more families with little primary sequence similarity sometimes make use of the same major structural... 

Figure 3.8. A simplified phylogenetic tree indicating the evolution of novel myoglobins in archeogastro-pod molluscs. Phylogenetic relationships of indoleamine 2,3-dioxygenases or IDOs, IDO-like myglobins, and a shrimp homolog are indicated. (Summary modified from Suzuki et al., 1998.)...

Wan L, Twitchett MB, Eltis LD, Mauk AG, Smith M (1998) In vitro evolution of horse heart myoglobin to increase peroxidase activity. Proc Natl Acad Sci USA 95 12825-12831... 

Comparison of the amino acid sequences of hemoglobin and myoglobin chains from different species of animals shows that the chains from related species are similar. The number of differences increases with phylogenetically more separated species. On the assumption that proteins evolve at a constant rate, the number of differences between two homologous proteins will be proportional to the time of divergence in evolution of the species. 

The evolution of cytochrome c and protein molecules in general has been the subject of many papers and reviews, and can be treated relatively briefly here. The starting points must be Anfinson s Molecular Basis of Evolution (57), based on the early amino acid sequence work, and the discovery that same year by Kendrew and Perutz of the identity of three-dimensional folding of the related proteins myoglobin and hemoglobin (98,99). These illustrate the two components of any study of mac-romolecular evolution the chemical sequence of the polymer and the folding of the polymer in three dimensions. 

See also Evolution of Myoglobin/Hemoglobin Proteins, Hemoglobin Variants, Thalassemias, Generation of Antibody Diversity... 

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