Tobacco Acid Pyrophosphatase (TAP) is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
that catalyses the hydrolysis of a
phosphoric ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are ...
bond in a broad spectrum of molecules, including the 5'-end of
mRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein.
mRNA is ...
.
During mRNA maturation the 5' triphosphate of the new mRNA molecule is rapidly removed. The diphosphate 5' end then attacks the α-phosphorus atom of a methylated
GTP to form a very unusual 5'-5' triphosphate linkage, called ''cap''. In molecular biology, TAP is used to hydrolyse a phosphodiester bond of this particular structure and release a mRNA molecule with only one phosphate group in the 5'-end,
for instance in protocols for
RACE (Rapid Amplification of cDNA Ends).
References
{{reflist
Enzymes