Biology Reference
In-Depth Information
Figure 5.
Inhibition ratio of VicK' protein autophosphorylation by six lead compounds with
antibacterial effects (from the 23 compounds). The inhibitory activities of the compounds for the
ATPase activity of the VicK' protein was measured using the Kinase-Glo™ Luminescent Kinase Assay.
Briefly, purified VicK' protein(6 μg/50 μl) was pre-incubated with compounds(final concentration,
200 μM) in a reaction buffer containing 40 mM Tris-HCl (pH 7.5), 20 mM MgCl
2
and 0.1 mg/ml BSA,
at room temperature for 10 min. Then ATP (5 μM) was added for another incubation of 10 min at
room temperature, and detected the rest amount of ATP.
Table 1.
Biological effects of six potential inhibitors of the VicK histidine kinase.
Chemical inhibitor
MIC (μM)
MBC (μM)
CC50 (μM) on
Vero cell
IC50 (μM) for VicK'
protein
Compound 1
100
>200
213
542.25
Compound 2
50
200
321 .33
562.41
Compound 3
100
>200
274.22
502.63
Compound 4
200
>200
360
>1000
Compound 5
100
>200
516.17
598.11
Compound 6
0.28
25
392
32.60
Compound 7
0.02
2.0
undone
undone
A 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay
was carried out on Vero cell line to determine the CC50 (concentration that induces a
50% cytotoxicity effect) values of these compounds. As shown in Table 1, the CC50
values of all these six compounds were larger than 200 μM and than their respective
MIC values, indicating low cytotoxicity effects on Vero cell. Collectively, these com-
pounds inhibited bacterial growth with low toxic effects.
