Quinolinic acid phosphoribosyltransf erase was purified WI-fold from the endosperm of etiolated seedlings of Ricinus communis L. Sodium dodecyl sulfate disc gel electrophoresis indicated that the enzyme was homogeneous but on analytical disc gel electrophoresis at pH 7.0 and 8.3 the isolated native protein exhibited three closely migrating bands. The three proteins were of the same molecular we...