Abstract
Oryzacystatin, a proteinaceous cysteine proteinase inhibitor (cystatin) from rice seeds and probably the first well-defined cystatin superfamily member of plant origin, was immunologically investigated for its occurrence in rice seeds during maturation and germination. The enzyme-linked immunosorbent assay (ELISA) using anti-oryzacystatin Immunoglobulin G showed that all the investigated 23 cultivars of rice, Oryza sativa L. japonica, contained Oryzacystatin at 1-4 mg% in their seeds. Particularly, Oryzacystatin levels were high in precocious cultivars and low in sticky rice cultivars. The use of the ELISA method for the representative rice cultivar, Nipponbare, gave the result that in the seed maturation process, Oryzacystatin was synthesized in precedence to total seed protein. In the germination process, Oryzacystatin tended to decrease in accordance with degradation of total seed protein.
