Demonstration of 5'-methylthioadenosine phosphorylase activity in various rat tissues. Some properties of the enzyme from rat lung

Biochim Biophys Acta. 1978 Mar 14;523(1):82-93. doi: 10.1016/0005-2744(78)90011-6.


An enzyme (5'-methylthioadenosine phosphorylase) that catalyzes the phosphorolytic cleavage of 5'-methylthioadenosine to 5-methylthioadenosine to 5-methylthioribose-1-phosphate and adenine was found in various rat tissues. Liver and lung had the highest enzyme activities and heart the lowest, most of the activity (greater than 90%) was recovered in soluble tissue fractions. The enzyme from rat lung was purified about 30-fold by pH treatment (NH4)2SO4 fractionation, and gel filtration. The enzyme did not require an added metal-ion for activity, and was not inhibited by EDTA. Many compounds were tested for their inhibitory effects; of these, ribose 1-phosphate, 2-deoxyribose 1-phosphate, fructose 1-phosphate, adenine and guanine were shown to inhibit. Kinetic patterns on reciprocal plots were linear as a function of the concentration of either 5'-methylthioadenosine or phosphate. More detailed kinetic studies suggested that the rat lung 5'-methylioadenosine phosphorylase catalyzes an equilibrium-ordered reaction, and that 5'-methylthioadenosine is the first substrate to bind and 5-methylthioribose-1-phosphate is the first product to be released.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine / analogs & derivatives
  • Animals
  • Kinetics
  • Liver / enzymology
  • Lung / enzymology*
  • Male
  • Pentosyltransferases / metabolism*
  • Purine-Nucleoside Phosphorylase / isolation & purification
  • Purine-Nucleoside Phosphorylase / metabolism*
  • Rats
  • Tissue Distribution


  • Pentosyltransferases
  • Purine-Nucleoside Phosphorylase
  • 5'-methylthioadenosine phosphorylase
  • Adenosine