The nature of the phosphatases associated with nucleotide metabolism in <i>Tetrahymena pyriformis</i>

Conner, Robert L.; MacDonald, L. A.

doi:10.1002/jcp.1030640210

Cited by 19 publications

(4 citation statements)

References 27 publications

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“…) (4, 7, 12). The degradation of 5'-mononucleotides has not been studied extensively, altho the activity of acid phosphatase toward some 5'-nucleotides has been noted (6,7,12). Conner and Macdonald (6) were unable to find evidence for a specific soluble 5'nucleotidase with a neutral or alkaline pH optimum, or for a distinct alkaline phosphatase in Tetrahymena.…”

Section: '-mentioning

confidence: 99%

“…Parallel experiments were run in 70 mM tris acetate, pH 4.5, and 70 mM tris chloride, pH 7.5. The reaction, which has been shown to be linear over a period of 30 min under these conditions ( 6 ) , was initiated by addition of enzyme and stopped by addition of 2 ml cold 12% perchloric acid. After standing 1.0-1.5 hr in an ice bath, the samples were centrifuged at 25,000 X g for 20 min.…”

Section: Substrate3mentioning

confidence: 99%

“…Aliquots of thc clear supernate were assayed for orthophosphate using a modification of the method of Fiske and SubbaRow ( 9 ) . All values were corrected for the initial orthophosphate content and for orthophosphate release in the absence of substrate ( 6 ) .…”

Section: Substrate3mentioning

confidence: 99%

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Purine and Pyrimidine 5′‐Nucleotide Catabolism in Tetrahymena pyriformis W1

Conner¹,

Linden²

1970

The Journal of Protozoology

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SYNOPSIS Deamination at pH 7.5 of adenosine, deoxyadenosine, cytidine and deoxycytidine by cell‐free preparations of Tetrahymena pyriformis W was observed both in the presence and absence of fluoride. Deamination of 5′‐AMP, 5′‐dAMP, 5′‐CMP, and 5′‐dCMP was found only in the absence of fluoride. Dephosphorylation of the above nucleotides by acid phosphatases occurred at pH 4.5; reduced activity was noted at pH 7.5. Fluoride effectively blocked acid phosphatase activity at both pH values. This correlation of phosphatase and deaminase activities suggests a catabolic pathway for 5′‐AMP and 5′‐CMP whereby dephosphorylation precedes deamination. Radiolabelled substrates were used to test this hypothesis. The experiments were designed so that conversion of as little at 1.0% of the radiolabelled substrate to the deaminated product could be detected. No 5′‐IMP or 5′‐UMP, the expected deamination products of 5′‐AMP and 5′‐CMP, respectively, was recovered after incubation of the radiolabelled substrates with cell‐free enzyme preparations. Thus, it appears that Tetrahymena has no 5′‐AMP or 5′‐CMP deaminases and that these compounds are deaminated only after conversion to nucleosides. Acid phosphatase activity toward 5′‐GMP, 5′‐dGMP, 5′‐TMP, 5′‐UMP, and 5′‐XMP was also found.

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Section: '-mentioning

confidence: 99%

Section: Substrate3mentioning

confidence: 99%

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Purine and Pyrimidine 5′‐Nucleotide Catabolism in Tetrahymena pyriformis W1

Conner¹,

Linden²

1970

The Journal of Protozoology

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“…In Tetrahymena, true AMPase has been reported to be absent (10) as has G6Pase activity in Tetrahymena, strain ST. which stores little glycogen (2 1). However, G6Pase activity has been enriched 4-fold in the microsomal fractions of Tetrahymena (27), and it has also been suggested that this activity may be active during gluconeogenesis in this cell under certain nutritional conditions (18).…”

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confidence: 99%

An Inhibition and Kinetic Study of Acid Phosphatase in Paramecium caudatum and Paramecium tetraurelia¹

Fok

1983

The Journal of Protozoology

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ABSTRACT. Inhibition, inactivation, pH, and kinetic studies using both homogenates and purified lysosomal fractions of Paramecium caudalum and of P. tetraurelia were carried out to examine the lysosomal acid phosphatase (AcPase) and its relationship to p‐nitrophenylphosphatase (pNPPase), glucose‐6‐phosphatase (G6Pase), and 5′‐nucleotidase (AMPase). The results generally support the idea that Paramecium cells contain a distinct lysosomal AcPase with a broad substrate specificity. The hydrolysis of glucose‐6‐phosphate (G6P) and adenosine 5′‐monophosphate (AMP) was shown to be due to this enzyme, suggesting that true G6Pase and AMPase may be lacking in these two species; however, some hydrolysis of AMP at pH 7.5 catalyzed by an unknown soluble enzyme distinct from alkaline phosphatase and Na+‐K+‐ATPase was observed. Since the hydrolysis of p‐nitrophenylphosphate (pNPP) at acid pH was also shown to be due to AcPase alone, pNPPase could be used as a rapid assay for Paramecium AcPase. At an alkaline pH, however, this activity was catalyzed by an alkaline phosphatase located in the cytosol fraction. P. caudatum AcPase was shown to have kinetic properties similar to those of purified rat liver and human prostatic AcPase and to have relative substrate affinities in the order of G6P < β‐glycerophosphate < pNPP < AMP. These different substrate affinities might account for the observed differences in the inhibition of the four lysosomal activities by NaF, L(+)‐tartrate, and molybdate, all of which inhibited the hydrolysis of G6P, β‐glycerophosphate, and pNPP competitively, but which exhibited a noncompetitive inhibition of a mixed type with the hydrolysis of AMP.

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Orthophosphate excretion as related to RNA metabolism in Tetrahymena

Cline

Conner

1966

Journal Cellular Physiology

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Log phase cultures of Tetrahymenu pyriformis W excrete orthophosphate, a purine, and a pyrimidine when suspended in a non-nutrient buffered medium. Ribonucleic acid has been established as the primary source of these catabolic products. Thirty per cent of the total cellular RNA was degraded in three hours under the conditions of growth and suspension employed. The size of the phosphorus pools of these ciliates was determined during the period of RNA degradation; the internal acidsoluble organic phosphate and the cellular orthophosphate pools remained constant for five hours at 20% and 5% of the total cell phosphorus respectively. The ultraviolet-absorbing materials excreted with the orthophosphate were identified as hypoxanthine and uracil. A pentose, presumably ribose, was excreted in small quantities, but was not equivalent in amount to the orthophosphate and did not parallel the pattern of release of the anion. The excretion of orthophosphate, hypoxanthine, and uracil is correlated with the catabolism of RNA as it has been demonstrated in these cells.

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The nature of the phosphatases associated with nucleotide metabolism in Tetrahymena pyriformis

Cited by 19 publications

References 27 publications

Purine and Pyrimidine 5′‐Nucleotide Catabolism in Tetrahymena pyriformis W1

Purine and Pyrimidine 5′‐Nucleotide Catabolism in Tetrahymena pyriformis W1

An Inhibition and Kinetic Study of Acid Phosphatase in Paramecium caudatum and Paramecium tetraurelia¹

Orthophosphate excretion as related to RNA metabolism in Tetrahymena

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The nature of the phosphatases associated with nucleotide metabolism in Tetrahymena pyriformis

Cited by 19 publications

References 27 publications

Purine and Pyrimidine 5′‐Nucleotide Catabolism in Tetrahymena pyriformis W1

Purine and Pyrimidine 5′‐Nucleotide Catabolism in Tetrahymena pyriformis W1

An Inhibition and Kinetic Study of Acid Phosphatase in Paramecium caudatum and Paramecium tetraurelia1

Orthophosphate excretion as related to RNA metabolism in Tetrahymena

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An Inhibition and Kinetic Study of Acid Phosphatase in Paramecium caudatum and Paramecium tetraurelia¹