>mbernhar at facstaff.wisc.edu wrote:
>To: parasite at net.bio.net>From: mbernhar at facstaff.wisc.edu (mat bernhardt)
>Subject: crypto question
>Date: 25 Mar 1995 01:49:38 GMT
>>does anyone know whether the oocyst walls of crypto possess any
>electrical
>charges?
>mbernhar at facstaff.wisc.edu>-----------------------------------------------------------
I don't know the answer for the intact wall, but part of the oocyst
antigen reported in the literature is highly charged (Lally,N.C.,
Baird,G.D., McQuay,S.J., Wright,F. and Oliver,J.J. (1992) A 2359-base
pair DNA fragment from Cryptosporidium parvum encoding a repetitive oocyst
protein. Mol. Biochem. Parasitol. 56, 69-78; Genebank M95743).
This gene fragment contains an ORF encoding 786 amino acids, containing 31
D, 45 E, 32 H, 39K, 58 Q & 22 R residues, roughly 10% negative charges and
19% positive changes. Plenty of charges, but does this represent the
general oocyst surface? I suspect much of the surface may be
oligosaccharides.
Has any one measured the charge on the oocyst surface? Obviously it would
infuence its ability to stick to surfaces (eg clay particles, humus) and
rate of sedimentation. Perhaps Alan Champion can comment?
Cheers, Martin Slade
Martin Slade,
School of Biological Sciences,
Macquarie University,
NSW 2109,
Australia
FAX (61 2) 850 8174
Phone(61 2) 850 8210
