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PNPP is classified as a chromogenic substrate because of its ability to transform from a colorless compound to a colored compound through a biological mechanism, dephosphorylation. [4] PNPP is used because of its low cost and the rate of the reactions can be measured over a wide range of substrate concentrations because the concentration of the ...
n/a Ensembl n/a n/a UniProt n a n/a RefSeq (mRNA) n/a n/a RefSeq (protein) n/a n/a Location (UCSC) n/a n/a PubMed search n/a n/a Wikidata View/Edit Human Purine nucleoside phosphorylase, PNP, PNPase or inosine phosphorylase (EC 2.4.2.1) is an enzyme that in humans is encoded by the NP gene. It catalyzes the chemical reaction purine nucleoside + phosphate ⇌ {\displaystyle \rightleftharpoons ...
This ability to catalyze a reaction with a secondary substrate is known as enzyme promiscuity, [1] and may have played a role in NPP's evolutionary history. [15] NPP's promiscuity enables the enzyme to share substrates with alkaline phosphatase (AP), another member of the alkaline phosphate superfamily. Alkaline phosphatase primarily hydrolyzes ...
The enzyme is an allosteric enzyme, so it can be converted from IMP, GMP and AMP in high concentration binds the enzyme to exerts inhibition while PRPP is in large amount binds to the enzyme which causes activation. So IMP, GMP and AMP are inhibitors while PRPP is an activator.
Substrates and inhibitors [ edit ] Comparative homology modelling of this enzyme in L. donovani suggest that among all of the computationally screened compounds, pentamidine , 1,3-dinitro adamantane , acyclovir and analogs of acyclovir had higher binding affinities than the real substrate (guanosine monophosphate). [ 3 ]
Polynucleotide Phosphorylase (PNPase) is a bifunctional enzyme with a phosphorolytic 3' to 5' exoribonuclease activity and a 3'-terminal oligonucleotide polymerase activity. [2] That is, it dismantles the RNA chain starting at the 3' end and working toward the 5' end. [1] It also synthesizes long, highly heteropolymeric tails in vivo.
The enzyme is involved in the synthesis of nucleotides (purines and pyrimidines), cofactors NAD and NADP, and amino acids histidine and tryptophan, [1] [2] [3] linking these biosynthetic processes to the pentose phosphate pathway, from which the substrate ribose 5-phosphate is derived.
In de novo generation of purines, the enzyme amidophosphoribosyltransferase acts upon PRPP to create phosphoribosylamine. [2] The histidine biosynthesis pathway involves the reaction between PRPP and ATP, which activates the latter to ring cleavage. Carbon atoms from ribose in PRPP form the linear chain and part of the imidazole ring in histidine.