F. Padillavaca et F. Anayavelazquez, BIOCHEMICAL-PROPERTIES OF A NEURAMINIDASE OF TRICHOMONAS-VAGINALIS, The Journal of parasitology, 83(6), 1997, pp. 1001-1006
Trichomonas vaginalis possesses a membrane-associated neuraminidase ac
tivity that is released into culture medium during its growth in vitro
. The neuraminidase shows an optimum pH of 4.5 and a K-m, of 0.15 mM f
or (4-methylumbelliferyl)-alpha-D-N-acetyl-neuraminic acid as a substr
ate. This enzyme releases mainly alpha-2,3-linked sialic acid because
it is able to liberate sialic acid from sialyllactose (mainly (alpha-2
,3) but not from mucin (alpha-2,6) or fixed erythrocytes (mainly alpha
-2,6). The neuraminidase activity is strongly inhibited by 2,3-dehydro
-2-deoxy-N-acetyl neuraminic acid, whereas EGTA and Ca2+ do not affect
the activity. Gel filtration-fast protein liquid chromatography of cu
lture supernatant displays a single peak of neuraminidase activity wit
h molecular weight 52,000. The levels of neuraminidase activity are va
riable in fresh and long-term grown isolates of T. vaginalis, regardle
ss of time in culture. However, there are 2 kinds of isolates, 1 group
with high neuraminidase activity and able to secrete the enzyme durin
g growth and the other with low neuraminidase activity. The results su
ggest that T. vaginalis possesses a membrane-associated neuraminidase
that is present to a variable degree in different isolates.