In ancient China, it was also used as a powerful tool to remove negative energies and drive away the hazards of daily life. Synthetic amethyst
Synthetic (laboratory-grown) amethyst is produced by a synthesis method called hydrothermal growth, which grows the crystals inside a high-pressure autoclave. Synthetic amethyst is made to imitate the best quality amethyst. Its chemical and physical properties are the same as that of natural amethyst and it can not be differentiated with absolute certainty without advanced gemmological testing (which is often cost-prohibitive). One test based on "Brazil law twinning" (a form of quartz twinning where right and left hand quartz structures are combined in a single crystal) can be used to identify most synthetic amethyst rather easily. Synthesizing twinned amethyst is possible, but this type is not available in large quantities in the market.Treated amethyst is produced by gamma ray, X-ray, or electron-beam irradiation of clear quartz (rock crystal), which has been first doped with ferric impurities. Exposure to heat partially cancels the irradiation effects and amethyst generally becomes yellow or even green. Much of the citrine, cairngorm, or yellow quartz of jewelry is said to be merely "burnt amethyst". Cultural history
Ancient Greece
The Greek word "amethystos" may be translated as "not drunken", from Greek a-, "not" + methustos, "intoxicated". Amethyst was considered to be a strong antidote against drunkenness, which is why wine goblets were often carved from it.
Biochemical studies of the enzyme have focused on proteins of ADSL from nonhuman species, the ADSL structure from the crystallized protein of Thermotoga maritime has been used, along with DNA sequencing data, to construct homology models for a variety of other organisms, including human ADSL. A variety of studies have been done using the equivalent enzyme from Bacillus subtilis, which shares a significant percentage of identity along with about some percentage of similarity in amino acid sequence with the human enzyme. Homology models overlaid on each other show a high degree of overlap between the enzymes.The family of enzymes to which ADSL belongs and that catalyze β-eliminations in which fumarate is one of the products are homotetramers with four active sites composed of amino acid residues from three distinct subunits. Much is known about the active site of human ADSL due to studies of the active site in the B. subtilis ADSL through affinity labeling and site-directed mutagenesis. While there is some variability among species in the sequencing of ADSL, the active site of the enzyme contains many residues that are conserved across species and have been shown to be critical to the enzymes function. His68 and His141 seem to serve as the general acid and base catalysts, and are critical to the catalyzing reaction of the substrate. His89 seems to enhance the binding of the substrates phosphoryl group and orient adenylosuccinate for catalysis. All three histidines are conserved throughout the 28 species for which the structure of ADSL is known.