Heterogeneity and molecular weight inter-relationships of the esterase isoenzymes of several invertebrate species

Abstract

1. 1. The multiple forms of esterase activity have been studied in the tissues of eight representative invertebrate species: the sea anemone, the liver fluke, the round worm, the segmented worm, the king prawn, the garden snail, the chiton and the sea cucumber. 2. 2. These esterases have been characterized in terms of their relative mobilities on polyacrylamide gel electrophoresis, substrate and inhibitor specificity, molecular weights and physicochemical properties. 3. 3. In the representative of the phylum Coelenterata, the sea anemone, eleven esterase multiple forms were characterized and included carboxylesterases and cholinesterases. In the liver fluke (phylum Platyhelminthes) eight esterases were distinguishable. All of these were again carboxylesterases and cholinesterases. 4. 4. Thirteen multiple forms of esterases were found in the round worm of the phylum Nematoda, while only ten were present in the representative of the phylum Annelida, the earth worm. Both these species contained carboxylesterase, cholinesterase and arylesterase forms. 5. 5. The most complex system was found in the tissues of the king prawn (phylum Arthropoda) with twenty-nine isoenzymes. In the garden snail, eighteen isoenzymes were found, but in the marine mollusc, the chiton, only eleven forms were distinguishable. All these species contain the three types of esterases classified in the round worm and the earth worm. 6. 6. In the sea cucumber, from the phylum Echinodermata, only five carboxylesterases were found. 7. 7. These results have been discussed in relation to the phylogenetic variability of the esterases, and the complex structural and genetic inter-relationships of these multiple enzyme forms.