Purification and properties of a protease from Lupinus angustifolius during germination.

A protease, present in Lupinus angustifolius cotyledons on the fifth day after germination and assayable by following the release of amino groups from gliadin has been purified to the degree that the associated protein of the extract is undetectable. The enzyme is capable, under varying conditions, of releasing amino groups from lupin alpha, beta and gamma conglutins and possesses a mean molecular weight, by dodecylsulphate/polyacrylamide gel electrophoresis and Sephadex G-75 gel filtration of 27500 +/- 450. The isoelectric point is 9.0 +/- 0.848 with a pH optimum of pH 4.0 using gliadin as substrate.