Journal
BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE
Volume 15, Issue -, Pages -Publisher
BIOMED CENTRAL LTD
DOI: 10.1186/s12906-015-0775-4
Keywords
Andrographolide sodium bisulphite; Urease; Inhibition; Slow-binding; Sulfhydryl group; Molecular docking
Categories
Funding
- National Science Foundation of China [81374043, 81173534]
- Ph.D. Programs Foundation of Ministry of Education of China [20134425110009]
- Science and Technology Innovation Project of Guangdong Provincial Department of Education [2013KJCX0045]
- Science and Technology Planning Project of Guangdong Province [2014A020221042]
- Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme
- Central Finance of China in Support of the Development of Local Colleges and University-Educational [276 (2014)]
Ask authors/readers for more resources
Background: The inhibitory effect of andrographolide sodium bisulphite (ASB) on jack bean urease (JBU) and Helicobacter pylori urease (HPU) was performed to elucidate the inhibitory potency, kinetics and mechanism of inhibition in 20 mM phosphate buffer, pH 7.0, 2 mM EDTA, 25 degrees C. Methods: The ammonia formations, indicator of urease activity, were examined using modified spectrophotometric Berthelot (phenol-hypochlorite) method. The inhibitory effect of ASB was characterized with IC50 values. Lineweaver-Burk and Dixon plots for JBU inhibition of ASB was constructed from the kinetic data. SH-blocking reagents and competitive active site Ni2+ binding inhibitors were employed for mechanism study. Molecular docking technique was used to provide some information on binding conformations as well as confirm the inhibition mode. Results: The IC50 of ASB against JBU and HPU was 3.28 +/- 0.13 mM and 3.17 +/- 0.34 mM, respectively. The inhibition proved to be competitive and concentration-dependent in a slow-binding progress. The rapid formation of initial ASB-JBU complex with an inhibition constant of K-i = 2.86 x 10(-3) mM was followed by a slow isomerization into the final complex with an overall inhibition constant of K-i* = 1.33 x 10(-4) mM. The protective experiment proved that the urease active site is involved in the binding of ASB. Thiol reagents (L-cysteine and dithiothreithol) strongly protect the enzyme from the loss of enzymatic activity, while boric acid and fluoride show weaker protection, indicating that the active-site sulfhydryl group of JBU was potentially involved in the blocking process. Moreover, inhibition of ASB proved to be reversible since ASB-inactivated JBU could be reactivated by dithiothreitol application. Molecular docking assay suggested that ASB made contacts with the important sulfhydryl group Cys-592 residue and restricted the mobility of the active-site flap. Conclusions: ASB was a competitive inhibitor targeting thiol groups of urease in a slow-binding manner both reversibly and concentration-dependently, serving as a promising urease inhibitor for the treatment of urease-related diseases.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available