Fig. 8.

Characterization of the highly purified activities and comparison with T. cruzi microsomal transferase activity. (A) Highly purified preparation of TcOGNT2cat (fraction 22 in Figure 7D and E) was analyzed for dependence of its transferase and hydrolase activities on the concentration of T16 peptide. The standard assay was conducted for 30 min in the presence of 50 μM UDP-GlcNAc. (B) Double-reciprocal plot of similar reactions conducted over a series of UDP-GlcNAc concentrations in the presence of 0.2 mM T16 peptide. (C) Microsomes from T. cruzi epimastigotes or TcOGNT2cat concentrated from L. tarentolae culture supernatants (as in Figure 4) were assayed for transferase activity in the absence (none) or presence of 0.2 mM T2, T16, or T29 peptides, at pH 8.0. (D) Independent samples were assayed for pH dependence in the 0.1 M Tris-maleate buffer using 0.2 mM T16.