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Drug precursors, also referred to as precursor chemicals or simply precursors, are substances used to manufacture illicit drugs. Most precursors also have legitimate commercial uses and are legally used in a wide variety of industrial processes and consumer products, such as medicines, flavourings, and fragrances.
In chemistry, a precursor is a compound that participates in a chemical reaction that produces another compound. In biochemistry , the term "precursor" often refers more specifically to a chemical compound preceding another in a metabolic pathway , such as a protein precursor .
Examples are mustard and nerve agents, and substances which are solely used as precursor chemicals in their manufacture. A few of these chemicals have very small-scale non-military applications; for example, minute quantities of nitrogen mustard are used to treat certain cancers. The Schedule 1 list is one of three lists.
It may be used as a precursor in one of the chemical reactions at the final stage of formation of a chemical listed in Schedule 1 or Schedule 2, part b It poses a significant risk to the object and purpose of this Convention by virtue of its importance in the production of a chemical listed in Schedule 1 or Schedule 2, part A;
The term 'listed precursor chemical' means a chemical specified by regulation of the Attorney General as a chemical that is used in manufacturing a controlled substance in violation of this title and is critical to the creation of the controlled substances, and such term includes (until otherwise specified by regulation of the Attorney General ...
In biochemistry, a zymogen (/ ˈ z aɪ m ə dʒ ən,-m oʊ-/ [1] [2]), also called a proenzyme (/ ˌ p r oʊ ˈ ɛ n z aɪ m / [3] [4]), is an inactive precursor of an enzyme.A zymogen requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site) for it to become an active enzyme.
From glycolysis, glucose 6-phosphate is a precursor for histidine; 3-phosphoglycerate is a precursor for glycine and cysteine; phosphoenol pyruvate, combined with the 3-phosphoglycerate-derivative erythrose 4-phosphate, forms tryptophan, phenylalanine, and tyrosine; and pyruvate is a precursor for alanine, valine, leucine, and isoleucine.
Precursors in the Halo series, an extremely advanced race that preceded and were destroyed by The Forerunners; Precursor, a 1999 novel set in C. J. Cherryh's Foreigner universe; Precursors, a fictional race (now extinct) of ancient beings in the board game Cosmic Encounter; Precursors, a fictional alien race in the Star Control video game series