Binding of Cd(II), Pb(II), and Zn(II) to a type 1 metallothionein from maize (Zea mays).

Metallothioneins (MTs) are a family of ubiquitous, low-molecular-mass, cysteine-rich proteins that play a significant role in maintaining intracellular metal homeostasis, eliminating metal toxification, and protecting cells against oxidative damages. Research activity on plant MTs, although known for 30 years, has only moderately increased in the past few years. In this study, a type 1 MT from maize (Zea mays) (ZmMT1) was successfully expressed in Escherichia coli strain BL21 (DE3). The UV absorption spectra recorded after the reconstitution of apo-ZmMT1 with different metals demonstrated that ZmMT1 can coordinate up to six Zn(II) ions, six Cd(II) ions, and even higher amounts of Pb(II). In addition, the general metal ion coordination abilities of ZmMT1 characterized by pH-dependent zinc-, lead- and cadmium-binding stability and by the competitive reaction with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) were evaluated. Results showed that the affinity of metal ions for the recombinant form of ZmMT1 can be arranged as follows: Cd(II) > Pb(II) > Zn(II). The observation revealed that chelating agents, such as ethylene diamine tetraacetic acid (EDTA) and ATP, accelerate the oxidation of ZmMT1 in the following order: EDTA ≫ L-histidine > ATP ≈ citrate. Meanwhile, commonly used buffers increase the reactivity of ZmMT1 with DTNB in the following order: PBS > Tris-HCl > HEPES.

Centrin: another target of monastrol, an inhibitor of mitotic spindle.

Monastrol, a cell-permeable inhibitor, considered to specifically inhibit kinesin Eg5, can cause mitotic arrest and monopolar spindle formation, thus exhibiting antitumor properties. Centrin, a ubiquitous protein associated with centrosome, plays a critical role in centrosome duplication. Moreover, a correlation between centrosome amplification and cancer has been reported. In this study, it is proposed for the first time that centrin may be another target of the anticancer drug monastrol since monastrol can effectively inhibit not only the growth of the transformed Escherichia coli cells in vivo, but also the Lu(3+)-dependent self-assembly of EoCen in vitro. The two closely related compounds (Compounds 1 and 2) could not take the same effect. Fluorescence titration experiments suggest that four monastrols per protein is the optimum binding pattern, and the binding constants at different temperatures were obtained. Detailed thermodynamic analysis indicates that hydrophobic force is the main acting force between monastrol and centrin, and the extent of monastrol inhibition of centrin self-assembly is highly dependent upon the hydrophobic region of the protein, which is largely exposed by the binding of metal ions.

[Modified Bazhengsan for urination symptoms of chronic prostatis with damp-heat accumulated in the lower jiao].

OBJECTIVE: To study the clinical effects of the modified formula of Bazhengsan on the urination symptoms of chronic prostatis with damp-heat accumulated in the lower jiao. METHODS: A total of 72 chronic prostatitis patients with damp-heat accumulated in the lower jiao were equally randomized to receive the modified formula of Bazhengsan (the trial group) and the primal Bazhengsan (the control group), both for a course of 28 days. Then we observed the changes in the NIH-CPSI scores, scores on Traditional Chinese Medicine (TCM) syndrome, maximum flow rate of urine (MFR) and results of the expressed prostatic secretion test (EPS). RESULTS: Among the 31 patients of the trial group, 6 were cured, 10 achieved excellent results, 9 got improved, and 6 failed to respond, with a total efficacy rate of 80.6%. While in the control group, 4 were cured, 10 achieved excellent results, 11 got improved, and 7 failed to respond, with a total efficacy rate of 78.1%. Significant improvement was observed in NIH-CPSI scores, TCM syndrome and EPS results in both of the groups (P < 0.05), and the trial group showed significant difference from the control in the improvement of urination symptoms (P < 0.05). CONCLUSION: Modified Bazhengsan is effective in the treatment of chronic prostatis with damp-heat in the lower jiao. It can significantly improve its clinical symptoms, especially urination symptoms.