Fig. 5.
Bactericidal activity of ubiquitin and ubiquitin-derived peptides. (A) Bactericidal activity against M. smegmatis of purified ubiquitin and cathepsin-treated ubiquitin. Bacteria were incubated with 25 μM purified ubiquitin or 25 μM preincubated with cathepsin B, D, or L overnight. (B) Bactericidal activity against M. smegmatis of purified ubiquitin and SF-treated ubiquitin. Bacteria were incubated overnight with 100 μM purified ubiquitin or 25 μM preincubated with 25 μg/ml SF (SF25). Statistical significance between SF25 and SF25+Ub100 treatment was determined by Student's t test (∗∗∗∗, P < 0.005). (C) M. tuberculosis viability in the presence of varying concentrations of Ub2 peptide over the indicated time course was determined by plating cfu.