scholarly journals CHARACTERIZATION OF PYRIMIDINE NUCLEOSIDE PHOSPHORYLASE ACTIVITY IN GASTRIC CARCINOMA

1999 ◽  
Vol 60 (2) ◽  
pp. 316-319
Author(s):  
Shin KOYAMA ◽  
Shinya TERASHIMA ◽  
Yutaka HOSHINO ◽  
Tomoyuki KANNO ◽  
Atai SATOH ◽  
...  
Keyword(s):  
Gastric Carcinoma ◽  
Pyrimidine Nucleoside ◽  
Phosphorylase Activity ◽  
Nucleoside Phosphorylase ◽  
Pyrimidine Nucleoside Phosphorylase

scholarly journals Characterization of pyrimidine nucleoside phosphorylase of Mycoplasma hyorhinis: implications for the clinical efficacy of nucleoside analogues

2012 ◽  
Vol 445 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Johan Vande Voorde ◽  
Federico Gago ◽  
Kristof Vrancken ◽  
Sandra Liekens ◽  
Jan Balzarini
Keyword(s):  
Nucleoside Analogues ◽  
Kinetic Properties ◽  
Virus Infections ◽  
Pyrimidine Nucleoside ◽  
Mycoplasma Hyorhinis ◽  
Nucleoside Phosphorylase ◽  
Secondary Infections ◽  
Pyrimidine Nucleoside Phosphorylase ◽  
In Silico Analyses

In the present paper we demonstrate that the cytostatic and antiviral activity of pyrimidine nucleoside analogues is markedly decreased by a Mycoplasma hyorhinis infection and show that the phosphorolytic activity of the mycoplasmas is responsible for this. Since mycoplasmas are (i) an important cause of secondary infections in immunocompromised (e.g. HIV infected) patients and (ii) known to preferentially colonize tumour tissue in cancer patients, catabolic mycoplasma enzymes may compromise efficient chemotherapy of virus infections and cancer. In the genome of M. hyorhinis, a TP (thymidine phosphorylase) gene has been annotated. This gene was cloned, expressed in Escherichia coli and kinetically characterized. Whereas the mycoplasma TP efficiently catalyses the phosphorolysis of thymidine (Km=473 μM) and deoxyuridine (Km=578 μM), it prefers uridine (Km=92 μM) as a substrate. Our kinetic data and sequence analysis revealed that the annotated M. hyorhinis TP belongs to the NP (nucleoside phosphorylase)-II class PyNPs (pyrimidine NPs), and is distinct from the NP-II class TP and NP-I class UPs (uridine phosphorylases). M. hyorhinis PyNP also markedly differs from TP and UP in its substrate specificity towards therapeutic nucleoside analogues and susceptibility to clinically relevant drugs. Several kinetic properties of mycoplasma PyNP were explained by in silico analyses.

Sign in / Sign up

Export Citation Format

Share Document