Trypanosome identification by electrophoresis of soluble enzymes.

IT is now generally accepted that interspecific differences are the result of inherited variations, developed during the course of evolution, in the structures (and amounts) of the proteins of the species concerned. Thus, although organisms of many diverse types possess cytochrome c, the cytochrome c molecules differ in structure, from organism to organism, to an extent which is related to the time that has elapsed since divergence from a common ancestor1, and the same is true for the haemoglobins of animals2. Intraspecies differences are the outward manifestations of less profound modifications affecting only a few of the proteins. Thus some human racial groups differ in the incidence of certain of the variant forms of plasma proteins and red cell enzymes, and also in the incidence of some of the blood group types (which are now recognized as resulting from the activities of variant enzymes)3. Clearly, if analogous proteins in different strains of a species could be characterized in some way, such as by electrophoresis, which shows up small structural differences, biochemical classification of the different strains would be possible, and this could be of some value as a taxonomic tool. Some advances along these lines have already been made : in the field of protozoology for instance, different strains as well as different species of the malarial parasite were recently reported to differ, to a lesser and greater degree respectively, in electrophoretic characteristics4.