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1. Chem a substance added in small amounts to a catalyst to increase its activity
2. Genetics a sequence of nucleotides, associated with a structural gene, that must bind with messenger RNA polymerase before transcription can proceed



a substance added to a catalyst in order to increase its activity, selectivity, or stability. A promoted catalyst is usually a catalyst containing a small amount of a promoter that by itself is catalytically inactive or only slightly active. In the case where the promoter is not inactive, the addition creates a mixed catalyst. Often an additive, given certain external conditions, concentrations, and methods of addition, acts as a promoter, whereas under different conditions the same additive serves as a catalyst poison. Most commercial catalysts belong to the promoted category. For example, V2Os, the catalyst which speeds up the oxidation of SO2 into SO3, is promoted by the oxides of alkali metals; metallic Fe, which catalyzes the synthesis of ammonia, is promoted by the oxides of aluminum, calcium, potassium, and other metals. The mechanism involved in the activity of promoters is explained by modern theories of catalysis.


A chemical which itself is a feeble catalyst, but greatly increases the activity of a given catalyst.
The site on deoxyribonucleic acid to which ribonucleic acid polymerase binds preparatory to initiating transcription of a gene or an operon.


1. A substance which accelerates a chemical reaction but appears to remain unchanged itself.
2. A hardener that accelerates cure of adhesives either with or without heat. Used primarily with synthetic resins.
References in periodicals archive ?
The P1c1 repressor binds to specific phage DNA operator sites adjacent to promotor sites.
His aim is to strengthen the Chamber's links with other city promotors to get the message across to the outside world.
I wanted to talk to my wife about it, and also speak to Chris Van Straaten (the British Speedway Promotors Association chairman) to clear it with regard to my position as manager of Great Britain Under 21s.
Generally, the promotors used to express genes in animal and plant cells do not work well in algae.
We have teamed up with the British Speedway Promotors Association to offer TWO pairs of tickets to the semi-final at Peterborough on August 8 and TWO pairs of terrace tickets for the final at Peterborough on August 10.
Cowboys & Indians' promotors believe that it could be as successful as recent British movies like The Full Monty, Four Weddings and a Funeral and Bend it Like Beckham.