ABSTRACT
The comparative study of the cholinesterase activity in some crab species was carried out for the first time with use of a set of thiocholine substrates. The substrate specificity was studied in stellar nerve, heart, and hemolymph of three crab species. The crab hemolymph was shown to be characterized by the highest enzyme activity. The enzyme from various crab organs has different structure o substrate specificity. Properties of crab enzymes was compared with acetylcholinesterase (AChE) of human blood erythrocytes, butyrylcholinesterase (BuChE) of horse blood serum, enzyme o squids and bivalve molluscs. The obtained data allow the conclusion to be made on differences in properties of enzymes both at the interspecies and at the tissue levels.
Subject(s)
Cholinesterases/chemistry , Crustacea/enzymology , Animals , Cattle , Hemolymph/enzymology , Horses , Kinetics , Myocardium/enzymology , Nerve Tissue/enzymology , Substrate Specificity , Thiocholine/chemistry , Tissue DistributionABSTRACT
The effects of environmental conditions on cholinesterase activity and kinetic parameters of substrate hydrolysis in the hemolymph of the mussel Crenomytilus grayanus were studied. Under seasonal upwellings, the cholinergic system efficiency is provided for by a wide range of efficient concentrations of the substrate, i.e., under such conditions the mussels at the molecular level have a quantitative adaptation strategy of the enzyme. In mussels from the stationary upwelling zone (at a steady low temperature of water) for efficiency of the cholinergic system, the quantitative strategy of enzyme adaptation is realized. In mussels from a highly contaminated site, irreversible damages to the cholinergic process were observed. The affinity of the substrate to the enzyme is highly informative and an appropriate biomarker for the load level and the adaptation capacity of the organism. The affinity of the substrate to the enzyme is recommended as a new biomarker.
