Stereoselective deamination of (5 ' RS)-5-methyl-2 ',3 '-isopropylidene adenosine catalyzed by adenosine deaminase: preparation of diastereomerically pure 5 '-methyl adenosine and inosine derivatives.

Adenosine deaminase from calf intestine catalyzes the stereoselective deamination of (5'S)-5'-methyl-2',3'-isopropylidene adenosine to the corresponding inosine derivative, so that by enzymatic deamination of (5'RS)-5'-methyl-2',3'-isopropylidene adenosine, the diastereomerically pure (5'S)-inosine and the unreacted (5'R)-adenosine derivatives can be efficiently prepared.