Abstract: With the primers designed basing on the terminal amino acid sequences of rice proteinase inhibitors and the preferred codons of rice genes, a new gene coding for a rice proteinase inhibitor has been amplified and cloned from Oryza sativa var. japonica (cv. Zhonghua 8) using PCR technique. The gene contains 408 basepairs and encodes 133 amino acid residues. The deduced amino acid sequence with duplicated Bowman-Birk type structure and active sites specific to trypsin has relatively high homology with that of proteinase inhibitors from wheats, beans etc. As for rice, the new gene shares 74.8% homology with a rice bran trypsin inhibitor reported previously. The evolutionary characteristics of the proteinase inhibitor family has also been discussed.

Key words: Bowman-Birk, Proteinase inhibitor, Evolution