1995
DOI: 10.1074/jbc.270.8.3706
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Lanterns of the Firefly Photinus pyralis Contain Abundant Diadenosine 5′,5“′-P1,P4-Tetraphosphate Pyrophosphohydrolase Activity

Abstract: The enzyme diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) pyrophosphohydrolase has been purified to homogeneity from firefly lanterns. It is a single polypeptide of M(r) 16,000 with a Km for Ap4A of 1.9 microM and kcat = 3.6 s-1. It is inhibited competitively by adenosine 5'-tetraphosphate (Ki = 7.5 nM) and non-competitively by fluoride ions (Ki = 50 microM). The specific activity of the enzyme in crude extracts of at least 20 milliunits/mg protein is 10-100 times higher than in any other eukaryote so far exam… Show more

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Cited by 12 publications
(8 citation statements)
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“…In vivo overexpression of mammalian TrpRS correlates with the elevated levels of Ap 3 A, not Ap 4 A [38]. Possible participation of the luciferase in the synthesis of Ap 4 A in vivo is indirectly supported by the unusually high level of Ap 4 A hydrolase activity in firefly lanterns [68].…”
Section: Ap N a Metabolismmentioning
confidence: 94%
“…In vivo overexpression of mammalian TrpRS correlates with the elevated levels of Ap 3 A, not Ap 4 A [38]. Possible participation of the luciferase in the synthesis of Ap 4 A in vivo is indirectly supported by the unusually high level of Ap 4 A hydrolase activity in firefly lanterns [68].…”
Section: Ap N a Metabolismmentioning
confidence: 94%
“…These conditions, although far away from the ones currently used in experiments of light emission, are presumably not very different from those found in nature. Besides, Ap 4 A has been found in the lanterns of P. pyralis , indicating that their synthesis could be more than a simple artifact [13].…”
Section: Introductionmentioning
confidence: 99%
“…The K i values estimated for the human enzyme, 1.6 and 2.3 nm, respectively, were over 30-and 20-fold lower than the K i estimated for the same enzyme for p 4 A (50 nm). Moreover, these values are five and three times smaller than the lowest K i estimated yet reported (7.5 nm) for the reaction of Ap 4 A hydrolysis catalysed by the firefly enzyme [52]. Significantly, the analogue, pppCH 2 pA, with its methylene bridge in the position most distant from the reaction site, is 100-fold less potent an inhibitor than ppCH 2 ppA.…”
Section: The Methylene Analogues Of P 4 a As Inhibitors Of The (Asymmmentioning
confidence: 65%
“…Adenosine tetraphosphate itself has been known for a long time as an effective competitive inhibitor of the (asymmetrical) Ap 4 A hydrolases. Examples of the reported inhibition constants are 48 nm for the rat liver enzyme [50], 30 nm for the enzyme from Ehrlich ascites tumour cells [51] and 7.5 nm, the lowest value reported to date, for the enzyme from firefly lanterns [52]. Owing to such low K i values, this nucleotide has been used for the elution of the (asymmetrical) Ap 4 A hydrolases adsorbed to dye-ligand affinity columns as homogeneous proteins [53,54].…”
Section: The Methylene Analogues Of P 4 a As Inhibitors Of The (Asymmmentioning
confidence: 99%