The Effects of Metal Ions in Euphorbia cf. lactea Latex on the Fibrinogenolytic Activity of a Plant Protease

Abstract

Two synchrotron-based techniques, synchrotron X-ray fluorescence (SXRF) and X-ray absorption spectroscopy (XAS), have demonstrated that Ca(2+) and Zn(2+) were the major metal ions distributed in the natural latex of Euphorbia cf. lactea. Both metal ions were found to affect the fibrinogenolytic activity of a homodimeric protease purified from the latex of this plant. The dimeric protein had an estimated molecular mass of about 82 kDa analyzed by SDS-PAGE. Therefore this protein was called as EuP-82. Based on the results of circular dichroism (CD) spectroscopy and the fibrinolytic activity measurement, it was found that Ca(2+) could activate the proteolytic activity of the enzyme by stabilizing its backbone structure. The intact conformation of EuP-82 was predicted from CD spectrum, which consisted of 51 % α-helix and 9 % β-sheet. Zn(2+) (10 mM) could decrease the fibrinolytic activity of EuP-82 to 30 ± 1 %. CD spectrum also supported that the inhibitory effect of Zn(2+) on the enzyme activity occurred by the drastic change of the enzyme structure with increasing the random coil conformation and by switching between α-helix and β-sheet structure. These results could be of first importance for further application to use EuP-82, the natural source protease as a potential drug for the thrombosis treatment. The fibrinolytic activity of EuP-82 may be enhanced by plasma Ca(2+) which generally involves in human hemostasis system.

Deciphering the Solvent Effect for the Solvation Structure of Ca2+ in Polar Molecular Liquids

“…Peak D is related to the transition from Ca 1s to Ca–O hybrid orbitals, which is supported by XAFS of CaO and another study . There are 33% p characters from Ca and 58.5% s and p characters from O in peak D shown in TD-DFT-calculated transitions, which verifies the transition to Ca–O hybrid orbitals.…”

Characterization of the binding of a glycosylated serine protease from Euphorbia cf. lactea latex to human fibrinogen

“…The thermodynamic profiles of the fibrinogen−EuP-82 binding (Fig. 4) and the previous study in the role of calcium in the secondary structure of EuP-82 [13] demonstrated that Ca 2+ could increase the fibrinogenolytic activity of the enzyme by stabilizing the secondary structure of enzyme and activating the binding of two molecules through hydrophobic interactions and hydrogen bond or van der Waals interactions. In addition, Ca 2+ also processed the interaction of fibrinogen and EuP-82 through the favorable reaction (G < 0 and H < 0).…”

“…The enzyme could cleave all chains of human fibrinogen . The fibrinogenolytic activity of the enzyme could be increased by the activator Ca 2+ and decreased by the inhibitor Zn 2+ . In this study, we further characterized the biochemical properties of EuP‐82, such as the binding of the enzyme with human fibrinogen, the functional role of glycosylation on its proteolytic activity.…”

“…A protease (designated as EuP-82) from Euphorbia cf. lactea latex was previously purified and was reported as a homodimeric serine protease [13,14]. The enzyme could cleave all chains of human fibrinogen [14].…”

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

“…Other workers also exploited synchrotron mapping techniques to show effects on plants; Cd in Arbuscular mycorrhizas, 261 Mn in the algae Chara coralline, 262 Zn in tomato and citrus, 263 Ce in cucumber 264 and Ca and Zn in Euphorbia. 265 The impact of engineered nanomaterials on plants, which act as a major point of entry of contaminants into trophic chains, was reported by Larue et al 266 The uptake of Ag-NPs in the lettuce crop, Lactuca sativa, aer foliar exposure and the possible biotransformation and phytotoxic effects was studied using m-SRXRF spectrometry and m-AS, TOF-SIMS and electron microscopy. Silver was found to be trapped on the lettuce leaves despite thorough washing; crucial information for those assessing the risk associated with products containing NPs.…”