Kinetic Properties of Digestive Carbohydrases and Proteases of Zooplankton

Abstract

Copepod carbohydrases and proteases obtained from acetone-dried powder were tested for the effects of various physical–chemical factors. Influences of pH, temperature, substrate concentration, and time of incubation were studied to establish the optimal enzyme assay conditions. Enzyme activities were found that catabolyzed most sugars assayed (amylose, laminarin, cellulose, maltose, cellobiose, lactose, trehalose, α-mannoside, etc.) as well as those catabolyzing most proteins (hemoglobin, albumin, azocoll, cowhide azur). The spectrum of digestive enzymes found is discussed in terms of natural substrate availability. Certain enzymes, such as mannosidase or the chitobiases could be related to the bacterial component in the copepod intestinal flora or diet. From direct and indirect evidences it was possible partially to identify the amylase as an α-amylase, the acid protease as a cathepsin-like enzyme, and one of the alkaline proteases as a trypsin-like enzyme.Key words: kinetic properties, carbohydrases, proteases, zooplankton