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SUMMARYIn previous studies, it was demonstrated through immunotechniques that the Varroa resorbs the ingested hemolymph proteins of honey bees (Apis mellifera) into it's own hemolymph. These same proteins are detectable in the eggs of this parasite (T EWARSON , 1981). To check this undegraded resorption of host proteins, a study of proteolytic activity in Varroa was carried out using homogenates of whole female mites in Tris-HCl-buffer (pH 8.2). Low proteolytic activity could be detected only with the help of very sensitive methods (by using synthetic substrates) and also there were indications that a protease inhibitory factor is present in the Apis hemolymph. A possible explanation of macromolecular uptake of host proteins by Varroa due to an inhibitory factor in the host hemolymph, as well as the low proteolytic activity in the mite, is discussed.

A chymotrypsin-like endopeptidase has been purified by ion-exchange chromatography, affinity chromatography, and gel filtration. The enzyme preparation is homogeneous in the ultracentrifuge and disc electrophoresis. The enzyme is proved to be free from any other proteolytic activities. The molecular weight of the proteinase as determined with several techniques (ultracentrifugation, gel filtration and electrophoresis without dodecylsulfate) is in the range between 13 000-14000 ; however, by dodecylsulfate gel electrophoresis a molecular weight of 23 000 was obtained. The obtained physical constants of hornet chymotrypsin are : sedimentation coefficient s ; , ,~ = 1 . 9 6~ s, diffusion coefficient D:o,w = 131 pm2 s-l, partial specific volume B = 0.737 ml g-l, frictional ratio f/fmin = 1.04, and degree of hydration = 0.1 g per g protein.During our investigation of the evolution of endopeptidases from invertebrates, Sonneborn et al. [I] have characterized a prot.einase from the midgut of the larva of the hornet, Vespa orientalis. This protease is homologous with mammalian chymotrypsin by such criteria as the complete inhibition by phenylmethylsulphonyl fluoride and Nu-tosyl-Lphenylalanine chloromethane and the cleavage specificity. However, by gel filtration on Sephadex the molecular weight was found to be 12 800. This molecular weight is much lower than that of previously known chymotrypsins from vertebrates and other invertebrates. Therefore the question arises, whether it is a true molecular weight or an artefact which could be result from interactions between Sephadex gel and the protein.The present paper describes a modified purification method of the hornet chymotrypsin and reports a study of its size and shape.

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