R. Perezmontfort et al., PROTEOLYTIC ACTIVITY IN EXTRACTS OF ENTAMOEBA-INVADENS AND ENTAMOEBA-HISTOLYTICA - A COMPARATIVE-STUDY, Acta protozoologica, 33(4), 1994, pp. 213-218
Two species of amoebae: Entamoeba invadens and Entamoeba histolytica a
re potentially invasive in reptiles and certain primates, respectively
. Since proteinases may be involved in pathogenic mechanisms (tissue n
ecrosis), at least in E. histolytica, it was of interest to compare th
eir proteases. We compared the sensitivity of proteolytic activity in
extracts of both species of amoebae to pH, temperature, and proteinase
inhibitors of different catalytic classes. Proteinases in extracts of
E. invadens were mainly inhibited in the presence of chelating agents
, in contrast to the partial or complete activation for proteinases of
E. histolytica. The pH-dependence curves for both types of extracts w
ere also different. When hide powder azure was used as a substrate, ex
tracts of E. histolytica showed a maximum of activity at pH 7 and a sh
oulder at pH 5, while extracts of E. invadens only showed a maximum at
pH 7.4. With azocasein as substrate, extracts of E. invadens had two
maxima of activity at pH 6 and 7.4, while extracts of E. histolytica h
ad a maximum at pH 6 and a shoulder at pH 7.4. The temperature optimum
for the digestion of azocasein was 60 degrees C for extracts of E. in
vadens and E. histolytica, but proteolytic activity in the latter was
more resistant to temperature. Analysis of lysates from both species o
f amoebae by substrate-gel electrophoresis, also showed marked differe
nces in the observed lysis zones. E. histolytica showed six hydrolysis
zones at with relative molecular masses of 66, 58, 42, 31, 28, and 23
kDa; and E. invadens showed only two zones, with relative molecular m
asses of 52 and 45 kDa. We conclude that although both species of amoe
bae contain mainly cysteine proteinases, the enzymes contained in both
types of cells are different.