The myoglobin of primates

The myoglobin of primates: the Night Monkey, Aotes trivirgatus (Cebidae, Platyrrhini, Anthropoidea)

The amino acid sequence of the myoglobin of the South American Night Monkey, Aotes trivirgatus, is identical to that of the marmoset (Callithrix jacchus [1]) except for residue 21 which is isoleucine in the marmoset, like in all other anthropoids, but valine in Aotes. Analysis of a possible pathway of the evolution of Aotes myoglobin using 18 known primate myoglobin sequences [2-5] supports the classification of the Night Monkey within Anthropoidea and Platyrrhini but it indicates that this species might be more closely related to the marmoset (family Callitrichidae) than to the family Cebidae as a member of which it is commonly classified.

The myoglobin of primates X

The amino acid sequences of skeletal muscle myoglobins from two old-world monkeys, Presbytis entellus and Erythrocebus patas, as well as one new-world monkey, Cebus apella wer inferred by homology of the tryptic and peptic peptides with the known sequence of human myoglobin and by selective dansyl-Edman degradation. These new sequences were examined phylogentically in conjunction with the 15 primate sequences already reported. It is clear that myoglobin evolution has been extremely conservative among cercopithecoid primates, so much so that the two surviving subfamilies cannot be distinguished using this protein.

Evolution of the amino acid substitution in the mammalian myoglobin gene

Multivariate statistical analyses were applied to 16 physical and chemical properties of amino acids. Four of these properties; volume, polarity, isoelectric point (charge), and hydrophobicity were found to explain adequately 96% of the total variance of amino acid attributes. Using these four quantitative measures of amino acid properties, a structural discriminate function in the form of a weighted difference sum of squares equation was developed. The discriminate function is weighted by the location of each particular residue within a given tertiary structure and yields a numerical discriminate or difference value for the replacement of these residues by different amino acids. This resulting discriminate value represents an expression of the perturbation in the local positional environment of a protein when an amino acid substitution occurs. With the use of this structural discriminate function, a residue by residue comparison of the known mammalian myoglobin sequences was carried out in an attempt to elucidate the positions of possible deviations from the known tertiary structure of sperm whale myoglobin. Only 11 of the 153 residue positions in myoglobin demonstrated possible structural deviations. From this analysis, indices of difference were calculated for all amino acid exchanges between the various myoglobins. All comparisons yielded indices of difference that were considerably lower than would be expected if mutations had been fixed at random, even if the organization of the genetic code is taken into consideration. On the basis of these results, it is inferred that some form of selection has acted in the evolution of mammalian myoglobins to favor amino acid substitutions that are compatible with the retention of the original conformation of the protein.

Complete amino acid sequence of the myoglobin from the Pacific sei whale, Balaenoptera borealis

The complete amino acid sequence of the major component myoglobin from Pacific sei whale, Balaenoptera borealis, was determined by specific cleavage of the protein to obtain large peptides which are readily degraded by the automatic sequencer. The acetimidated apomyoglobin was selectively cleaved at its two methionyl residues with cyanogen bromide and at its three arginyl residues by trypsin. From the sequence analysis of four of these peptides and the apomyoglobin, over 75% of the covalent structure of the protein was obtained. The remainder of the primary structure was determined by the sequence analysis of peptides that resulted from further digestion of the amino-terminal and central cyanogen bromide fragments. The amino-terminal fragment was specifically cleaved at its two tryptophanyl residues with N-chlorosuccinimide and the central cyanogen bromide fragment was cleaved at its glutamyl residues with staphylococcal protease and at its single tyrosyl residue with N-bromosuccinimide. The primary structure of this myoglobin proved identical with that from the gray whale but differs from that of the finback whale at four positions, from that of the minke whale at three positions and from the myoglobin of the humpback whale at one position. The above sequence identities and differences reflect the close taxonomic relationship of these five species of Cetacea.

The myoglobin of the fruit-bat (Rousettus aegyptiacus)

The myoglobin of the fruit-bat (Rousettus aegyptiacus) has been investigated. It has 153 amino acid residues. When the possible therian ancestral myoglobin is taken into consideration, the myoglobin of the fruit-bat resembles most closely that of the hedgehog.

The covalent structure of dog myoglobin

The primary structure of the myoglobin of the domestic dog (German shepherd) was studied. Tryptic and thermolytic peptides were compared with the sequence of other known myoglobins; the stepwise automatic Edman's degradation of the whole globin and also the chymotryptic digestion of the median fragment obtained by CNBr cleavage completed this sequence. Comparison of the established dog myoglobin structure with those from other carnivora shows 16 differences versus badger, 20 versus harbour seal and 15 versus California sea lion.

The myoglobin of primates. VIII. Gorilla gorilla beringei (eastern highland gorilla)

On aligning the tryptic peptides of the myoglobin from a gorilla with the homologous human peptides, one amino acid difference was found. By dansyl-Edman degradation this was shown to be at position 22, i.e. at a position other than those where man, chimpanzee and gibbon differ from one another.

The myoglobin of primates. VII. Perodicticus potto edwarsi (potto)

The primary structure of the myoglobin of the prosimian Lorisidae Perodictius potto edwarsi (potto) was studied. Tryptic, chymotryptic, peptic, subtilisin and thermolysin peptides were aligned against the sequence of human myoglobin. Sixteen differences were found which were confirmed by sequential analysis. On comparison of the West African potto with two other prosimian myoglobins known so far, there were 12 differences between the potto and the galago (East African) and 18 differences between the potto and the sportive lemur (Madagascar).