TRYPSIN INHIBITOR AND TRYPSIN-LIKE PROTEASE ACTIVITY IN AIR OR SUBMERGENCE-GROWN RICE (ORYZA SATIVA L) COLEOPTILES

摘要

Changes of trypsin inhibitor (TI) and trypsin-like protease activities of rice (Oryza sativa L.) coleoptiles grown under air or submergence conditions were investigated. Activity staining of TIs on a 15% SDS-PAGE gel showed that there were two TI bands (33.6 and 21.4 kDa) in Tainung 67 (TNG.67, a Japonica cultivar) and three bands (33.6, 21.4 and 12.8 kDa) in Taichung Native 1 (TN.1, an Indica cultivar). Each TNG.67 or TN.1 TI that was eluted from SDS-PAGE gels could inhibit trypsin-like proteinase activity in coleoptile crude extract. In air-grown coleoptiles, TI activity determined by the inhibition of trypsin-catalyzed casein or N-alpha-benzoyl-L-arginine-4-nitroanilide (Bz-L-Arg-4-NA) hydrolysis decreased 6 days after imbibition; and strength of TI bands on SDS-PAGE gels also decreased 7 days after imbibition. In contrast, proteinase activity determined by casein hydrolysis and trypsin-like protease activity determined by Bz-L-Arg-4-NA hydrolysis both reached maxima 6 days after imbibition in air-grown coleoptiles. Soluble protein contents in air-grown coleoptiles decreased but free amino acid contents increased 7 days after imbibition. When seedlings at 3 days after imbibition were exposed to submergence for 2 days, TI activity and strength of TI bands decreased. Soluble protein contents in submergence-grown coleoptiles also decreased but free amino acid contents increased, These submergence effects were inhibited by 10(-6) M ABA. [References: 35]