Mode and extent of degradation of adenosine and guanosine by extracts of Aspergillus terricola

Elshafei, Ali M.; Abu-Shady, M. R.; El-Beih, Fawkia M.; Mohamed, Latifa A.

doi:10.1016/s0944-5013(11)80008-x

Cited by 5 publications

(5 citation statements)

References 16 publications

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“…The present research study indicates the presence of adenosine deaminase in cell-free extracts of a filamentous fungus namely P. politans NRC-510. (MOHAMED 1993) in that the latter does not contain deaminating activity of adenosine and differs from Aspergillus terricola DSM 853 (ELSHAFEI et al 1995) in that extracts of P. politans NRC-510 does not contain any hydrolytic activities for the cleavage N-glycosidic bond of adenosine. The results also show that optimal activity of P. politans NRC-510 adenosine deaminase takes place at pH 6.0 and 45 °C, this pH and temperature is slightly lower than that obtained in case of Asp.…”

Section: Discussionmentioning

confidence: 99%

Deamination of adenosine by extracts of Penicillium politans NRC‐510

Elshafei

Mohamed

Ali

2005

J. Basic Microbiol.

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Cell-free extracts of nitrate-grown Penicillium politans NRC-510 could catalyze the hydrolytic deamination of adenosine to inosine maximally at pH 6.0 and 45 degrees C. However the same extracts could not catalyze the N-glycosidic bond cleavage of adenosine at pH 4.0, 6.0 and 8.0. Incubation of the extracts at 55 degrees C for 30 minutes caused about 31% loss in activity whereas incubation of the extracts at 60 degrees C for 15 minutes caused a complete loss of enzyme activity. Results indicated the absence of the involvement of sulfhydryl groups in the catalytic site of adenosine deaminase. The enzyme is inhibited by ethylene diamine tetraacetate indicating that adenosine deaminase is a metalloenzyme. MnCl2 and MgCl2 had a remarkable activating effect, whereas HgCl2, CaCl2 and ZnSO4 showed an inhibitory effect on enzyme activity. Dialyzing the extracts for 24 hours significantly increase deaminase activity by about 33%. The apparent K(m) value was calculated for adenosine and found to be 3.63 x 10(-3) M, which indicates high affinity of adenosine deaminase for its substrate adenosine.

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Section: Discussionmentioning

confidence: 99%

Deamination of adenosine by extracts of Penicillium politans NRC‐510

Elshafei

Mohamed

Ali

2005

J. Basic Microbiol.

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“…In the case of other eukaryotes, nucleoside hydrolases have been found in yeast [ 28 ], fungi [ 29 , 30 , 31 , 32 , 33 ], nematodes [ 34 , 35 ], insects [ 36 ], and fish [ 37 ]. In addition, genes homologous to various Rih hydrolases have been found in other eukaryotes, but the enzymes encoded by these genes have not been studied.…”

Section: Physiological Role Of Rih Family Proteinsmentioning

confidence: 99%

Ribonucleoside Hydrolases–Structure, Functions, Physiological Role and Practical Uses

Shaposhnikov,

Savin,

Tishkov

et al. 2023

Biomolecules

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Ribonucleoside hydrolases are enzymes that catalyze the cleavage of ribonucleosides to nitrogenous bases and ribose. These enzymes are found in many organisms: bacteria, archaea, protozoa, metazoans, yeasts, fungi and plants. Despite the simple reaction catalyzed by these enzymes, their physiological role in most organisms remains unclear. In this review, we compare the structure, kinetic parameters, physiological role, and potential applications of different types of ribonucleoside hydrolases discovered and isolated from different organisms.

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“…Addition of EDTA at a concentration of 5 × 10 -3 M caused an inhibition of about 50%, however a complete inhibition for enzyme activity was obtained at 10 -2 M EDTA. MgSO 4 , CoSO 4 and ZnSO 4 at a final concentration of 5 × 10 -3 M showed activation of ribonucleoside hydrolase.Enzymes which cleave the N-glycosidic bonds of purine and pyrimidine ribonucleosides fall into three general classes (GHANEM 1982) namely phosphorylases (WEST 1995), transferases (CHAWDHRI et al 1991) and hydrolases (ELZAINY et al 1990, ELSHAFEI et al 1995. Ribonucleoside hydrolases catalyze the hydrolytic cleavage of ribonucleosides into their respective bases and free pentose.…”

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confidence: 99%

“…Enzymes which cleave the N-glycosidic bonds of purine and pyrimidine ribonucleosides fall into three general classes (GHANEM 1982) namely phosphorylases (WEST 1995), transferases (CHAWDHRI et al 1991) and hydrolases (ELZAINY et al 1990, ELSHAFEI et al 1995. Ribonucleoside hydrolases catalyze the hydrolytic cleavage of ribonucleosides into their respective bases and free pentose.…”

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confidence: 99%

“…In the literature few studies on purine ribonucleoside cleavage by extracts of filamentous fungi were reported. The cleavage of the N-glycosidic bond of nucleosides by enzymes from organisms belonging to the filamentous fungi were reported in extracts of Penicillium chrysogenum (ELZAINY and ALLAM 1973), Aspergillus niger (ELZAINY et al 1978, HASSAN et al 1979, Neurospora crassa (TRIVEDI and MATTO 1979), Penicillium oxalicum (ALLAM et al 1981, HASSAN et al 1982, HASSAN et al 1983, P. citrinum (ELZAINY et al 1990, ALLAM et al 1991, Fusarium moniliforme (ELZAINY et al 1984) and A. terricola (ABU-SHADY et al 1994, ELSHAFEI et al 1995. This ribonucleoside hydrolase catalyzes the formation of free ribose from adenosine, guanosine and inosine.…”

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confidence: 99%

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Hydrolytic cleavage of purine ribonucleosides in Aspergillus phoenicis

Abdel‐Fatah

Elsayed²,

Elshafei

2003

J. Basic Microbiol.

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Cell-free extracts of nitrate-grown Aspergillus phoenicis could catalyze the hydrolytic cleavage of the N-glycosidic bond of inosine, guanosine and adenosine to the corresponding base and ribose by the nucleoside hydrolase. No evidence was obtained concerning the hydrolytic degradation of N-glycosidic bond of pyrimidine ribonucleosides namely cytidine and uridine by the same extracts. Optimum pH and temperature for adenosine, guanosine and inosine hydrolysis were the same at pH 3.5 and 55 degrees C, respectively. Citrate buffer showed the highest hydrolase activity when compared to the analogous activity obtained with the other buffers used. The rate of hydrolysis of the three nucleosides was in the order inosine > guanosine > adenosine. Incubation of extracts at 55 degrees C for 15 minutes caused about 85%, 75% and 62% loss of activity with adenosine, guanosine and inosine respectively. Dialyzing the extract caused a decrease in enzyme activity. Addition of inorganic arsenate to the reaction mixture (containing adenosine, guanosine or inosine) did not affect the amount of ribose liberated. Addition of EDTA at a concentration of 5 x 10(-3) M caused an inhibition of about 50%, however a complete inhibition for enzyme activity was obtained at 10(-2) M EDTA. MgSO4, CoSO4 and ZnSO4 at a final concentration of 5 x 10(-3) M showed activation of ribonucleoside hydrolase.

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Mode and extent of degradation of adenosine and guanosine by extracts of Aspergillus terricola

Cited by 5 publications

References 16 publications

Deamination of adenosine by extracts of Penicillium politans NRC‐510

Deamination of adenosine by extracts of Penicillium politans NRC‐510

Ribonucleoside Hydrolases–Structure, Functions, Physiological Role and Practical Uses

Hydrolytic cleavage of purine ribonucleosides in Aspergillus phoenicis

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