[Enzymologic characterization of adenosine nucleosidase of medicinal plants (Medicago sativa)].
Adenosine nucleosidase (adenosine ribohydrolase, E C 3.2.2.7) was purified from alfalfa leaf juice. The final preparation shows a single band on polyacrylamide gel electrophoresis; the enzyme activity is stable for 12 hrs between pH 5.5 and pH 8.5, but is completely lost on heating at 55 degrees C for 10 min. Optimal pH for the hydrolysis of adenosine is between pH 5 and pH 6. Among nine purine nucleosides tested, only adenosine, 2'-deoxyadenosine and purine riboside were hydrolyzed by the enzyme preparation. A Km value of 7 x 10(-6) M was found with adenosine as substrate at pH 7.4. Of the two reaction products, adenine exerted a weak inhibitory effect, while D-ribose was without effect on the initial rate of adenosine hydrolysis. The data reported are compared with those obtained on the enzymes from other plant sources.
D000241:Adenosine; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D000455:Medicago sativa; D009699:N-Glycosyl Hydrolases / Q000032:analysis*; D010946:Plants, Medicinal / Q000201:enzymology; D013696:Temperature
D009699:N-Glycosyl Hydrolases; C019599:adenosine nucleosidase; D000241:Adenosine
Caratterizzazione enzimologica dell'adenosina nucleosidasi di erba medica (Medicago sativa).