Effects of some modulators on purine nucleoside phosphorylase activity in myocardial tissue

Abstract

Purine nucleoside phosphorylase (PNP) in mammalian tissue is an enzyme responsible for formation of purine bases in DNA. It is also believed that PNP is crucial under energy-deprived conditions for the cell to metabolise adenosine during ATP degradation. This work describes a new method for determination of PNP activity in myocardial tissue using a commercially available substrate, 2-amino-6-mercapto-7-methylpurine riboside (MESG). The method involves the photometric assessment of the reaction between PNP (extracted from myocardial tissue) and MESG. Quantification as well as temperature- and pH-dependency for myocardial PNP activity is described. Also, the effect of some modulators has been studied. We have established the presence of PNP activity in pig myocardial tissue. Further, the results indicate a pH tolerance under slightly acid conditions and a calcium ion dependence of the enzyme.

Key Words::

• Analytical chemistry
• myocardium
• purine-nucleoside phosphorylase
• enzyme activity
• myocardial ischemia

Acknowledgments

Financial support from the Swedish Heart and Lung Foundation is gratefully acknowledged.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of this paper.