Naegleria fowleri is a free-living amoeba, known as a causative agent for a fatal disease
of the central nervous system (CNS) in man such as Primary amoebic
meningoencephalitis (PAM). Factors contributing to its pathogenicity and its distribution
in the environment have been investigated by previous researchers. In case of its
pathogenicity, several enzymes such as phospolipase A and sphingomyelinase, have been
proposed to probably act as aggressors in promoting PAM but no study so far have been
conducted to investigate the presence of proteinase enzyme in this amoeba although a
56kDa cystein proteinase enzyme has been identified in Entamoeba histolytica as an
important contributing factor in the amoeba’s virulence. In this preliminary study, a
pathogenic amoeba, Naegleria fowleri (strain NF3) was examined for the presence of
proteinases. Samples of enzymes in this amoeba were analysed by electrophoresis using
SDS-PAGE-gelatin gels. The results showed that this amoeba possesses at least two high
molecular weight proteinases on gelatin gels; their apparent molecular weights are ~128
kDa and ~170 kDa. Band of ~128 kDa enzyme is membrane-associated and its activity is
higher at alkaline pH compared wit h lower pH; at lower pH, its activity is greatly
stimulated by DTT. The ~170 kDa band enzyme appears to be inactivated at pH 8.0, atlower ph its activity is higher and DTT-dependance. The activity of this enzyme is
partially inhibited by inhibitor E-64 but markedly inhibited to antipain suggesting it
belongs to the cysteine proteinase group.