Bovine brain purine-nucleoside phosphorylase purification, characterization, and catalytic mechanism

Biochemistry ◽  
1976 ◽  
Vol 15 (20) ◽  
pp. 4451-4457 ◽  
Author(s):  
Arthur S. Lewis ◽  
Morton D. Glantz
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Bovine Brain ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase

Linear Free Energy Relationships for N(7)-Substituted Guanosines as Substrates of Calf Spleen Purine Nucleoside Phosphorylase. Possible Role of N(7)-Protonation as an Intermediary in Phosphorolysis

1993 ◽  
Vol 48 (9-10) ◽  
pp. 803-811 ◽  
Author(s):  
Agnieszka Bzowska ◽  
Ewa Kulikowska ◽  
David Shugar
Keyword(s):  
Acid Hydrolysis ◽  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Enzymatic Reaction ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase ◽  
Linear Free Energy ◽  
Repair Enzymes ◽  
Substrate Properties ◽  
Energy Relationships

Abstract Quantitative structure-activity relationships (QSAR) for a series of N(7)-substituted guanosines as substrates for calf spleen purine nucleoside phosphorylase (PNP) were developed, and compared with those for acid hydrolysis of these analogues. There is no correlation between the rates for enzymatic phosphorolysis and acid hydrolysis, indicating that for the enzymatic reaction labilization of the glycosidic bond is not the only, nor the predominant, effect of N(7)-substitution. Multiple regression analysis of the enzymatic process revealed that optimal substrate properties (minimal Michaelis constant) are associated with the Taft electronic constant equal zero and a substituent size, parametrized by the Taft steric constant, smaller than that for a methyl group. These results support the hypothesis of protonation of the N(7)-position of the base by the enzyme as a catalytic mechanism for calf spleen PNP. Attention is drawn to the postulated similar mechanism of action of other purine N-glycosidases, including plant antiviral proteins which function as RNAN-glycosidases, and possibly some DNA N-glycosidases which function as repair enzymes

Purine Nucleoside Phosphorylase. 2. Catalytic Mechanism†

Biochemistry ◽  
1997 ◽  
Vol 36 (39) ◽  
pp. 11735-11748 ◽  
Author(s):  
Mark D. Erion ◽  
Johanna D. Stoeckler ◽  
Wayne C. Guida ◽  
Richard L. Walter
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase

Purification and characterization of purine nucleoside phosphorylase from developing embryos of Hyalomma dromedarii

1991 ◽  
Vol 69 (4) ◽  
pp. 223-231 ◽  
Author(s):  
Mamdouh Y. Kamel ◽  
Afaf S. Fahmy ◽  
Abdel H. Ghazy ◽  
Magda A. Mohamed
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Kinetic Studies ◽  
Purine Nucleoside ◽  
Hyalomma Dromedarii ◽  
Ph Optimum ◽  
Nucleoside Phosphorylase ◽  
Apparent Homogeneity ◽  
Camel Tick

Purine nucleoside phosphorylase from Hyalomma dromedarii, the camel tick, was purified to apparent homogeneity. A molecular weight of 56 000 – 58 000 was estimated for both the native and denatured enzyme, suggesting that the enzyme is monomeric. Unlike purine nucleoside phosphorylase preparations from other tissues, the H. dromedarii enzyme was unstable in the presence of β-mercaptoethanol. The enzyme had a sharp pH optimum at pH 6.5. It catalyzed the phosphorolysis and arsenolysis of ribo- and deoxyribo-nucleosides of hypoxanthine and guanine, but not of adenine or pyrimidine nucleosides. The Km values of the enzyme at the optimal pH for inosine, deoxyinosine, guanosine, and deoxyguanosine were 0.31, 0.67, 0.55, and 0.33 mM, respectively. Inactivation and kinetic studies suggested that histidine and cysteine residues were essential for activity. The pKa values determined for catalytic ionizable groups were 6–7 and 8–9. The enzyme was completely inactivated by thiol reagents and reactivated by excess β-mercaptoethanol. The enzyme was also susceptible to pH-dependent photooxidation in the presence of methylene blue, implicating histidine. Initial velocity studies showed an intersecting pattern of double-reciprocal plots of the data, consistent with a sequential mechanism.Key words: Acarina, Hyalomma dromedarii, purine nucleoside phosphorylase, kinetics, active site, catalytic mechanism.

Open and closed conformation of the E. coli purine nucleoside phosphorylase active center and implications for the catalytic mechanism

2002 ◽  
Vol 315 (3) ◽  
pp. 351-371 ◽  
Author(s):  
Gertraud Koellner ◽  
Agnieszka Bzowska ◽  
Beata Wielgus-Kutrowska ◽  
Marija Luić ◽  
Thomas Steiner ◽  
...  
Keyword(s):  
Active Center ◽  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase ◽  
E Coli ◽  
Closed Conformation

Validation of the catalytic mechanism of Escherichia coli purine nucleoside phosphorylase by structural and kinetic studies

Biochimie ◽  
2011 ◽  
Vol 93 (9) ◽  
pp. 1610-1622 ◽  
Author(s):  
Goran Mikleušević ◽  
Zoran Štefanić ◽  
Marta Narczyk ◽  
Beata Wielgus-Kutrowska ◽  
Agnieszka Bzowska ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Kinetic Studies ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase

New catalytic mechanism for human purine nucleoside phosphorylase

2005 ◽  
Vol 327 (3) ◽  
pp. 646-649 ◽  
Author(s):  
Fernanda Canduri ◽  
Valmir Fadel ◽  
Luiz Augusto Basso ◽  
Mário Sérgio Palma ◽  
Diógenes Santiago Santos ◽  
...  
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Catalytic Mechanism ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase
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