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EC 6.3.4.21 Details
show Brenda entryEC number
6.3.4.21
Accepted name
nicotinate phosphoribosyltransferase
Reaction
nicotinate + 5-phospho-α-D-ribose 1-diphosphate + ATP + H2O = β-nicotinate D-ribonucleotide + diphosphate + ADP + phosphate
Other name(s)
niacin ribonucleotidase,
nicotinic acid mononucleotide glycohydrolase,
nicotinic acid mononucleotide pyrophosphorylase,
nicotinic acid phosphoribosyltransferase,
nicotinate-nucleotide:diphosphate phospho-α-D-ribosyltransferase
Systematic name
5-phospho-α-D-ribose 1-diphosphate:nicotinate ligase (ADP, diphosphate-forming)
CAS registry number
9030-26-6
Comment
The enzyme, which is involved in pyridine nucleotide recycling, can form β-nicotinate D-ribonucleotide and diphosphate from nicotinate and 5-phospho-α-D-ribose 1-diphosphate (PRPP) in the absence of ATP. However, when ATP is available the enzyme is phosphorylated resulting in a much lower Km for nicotinate. The phospho-enzyme is hydrolysed during the transferase reaction, regenerating the low affinity form. The presence of ATP shifts the products/substrates equilibrium from 0.67 to 1100 [4].
History
created 1961 as EC 2.4.2.11, transferred 2013 to EC 6.3.4.21
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1 Oxidoreductases
1.1 Acting on the CH-OH group of donors
1.14.13.45 created 1992, deleted 2003
