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.

Concanavalin A-mediated agglutination of plant plastids.

Cucumber (Cucumis sativus L.) and pear (Pyrus domestica Medik.) fruit proplastids, and pea (Pisum sativum L., cv. Meteor) leaf chloroplasts, extracted by osmotic rupture of protoplasts isolated after degradation of the cell walls by cellulase and pectinase, agglutinated in the presence of Con A. Agglutination of cucumber proplastids was inhibited by anti-Con A and by methyl α D-gluco/manno pyranosides but not by methyl α D-galactopyranoside. Fluorescein isothiocyanate-conjugated Con A (FITC-Con A) rendered agglutinated clumps fluorescent. If cellulase was omitted from the macerating medium, Con A-mediated agglutination did not occur even if proplatids were subsequently incubated with cellulase. Proplastids and chloroplasts extracted by conventional mechanical disruption methods were not agglutinated by Con A and did not acquire fluorescence with FITC-Con A. However, cucumber proplastids so extracted could be agglutinated by Con A if incubated with cellulase after preparation.