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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
1.1.1.70 created 1965, deleted 1978 1.1.1.74 created 1972, deleted 1976 1.1.1.89 created 1972, deleted 1976 1.1.1.109 created 1972, deleted 1976 1.1.1.139 created 1972, deleted 1978 1.1.1.155 created 1976, deleted 2004 1.1.1.171 created 1978, deleted 1984 1.1.1.180 created 1983, deleted 1984 1.1.1.182 created 1983, deleted 1990 1.1.1.204 created 1972 as EC 1.2.1.37, transferred 1984 to EC 1.1.1.204, modified 1989, deleted 2004 1.1.1.242 created 1992, deleted 2001 1.1.1.253 created 1999, deleted 2003
1.1.2 With a cytochrome as acceptor
