tailieunhanh - Báo cáo khoa học: Purification and characterization of cathepsin B-like cysteine protease from cotyledons of daikon radish, Raphanus sativus

Plant cathepsin B-like cysteine protease (CBCP) plays a role in disease resistance and in protein remobilization during germination. The ability of animal cathepsin B to function as a dipeptidyl carboxypeptidase has been attributed to the presence of a dihistidine (His110-His111) motif in the occluding loop, which represents a unique structure of cathepsin B. | ỊFEBS Journal Purification and characterization of cathepsin B-like cysteine protease from cotyledons of daikon radish Raphanus sativus Akihiko Tsuji Yayoi Kikuchi Kentaro Ogawa Hiroko Saika Keizo Yuasa and Masami Nagahama Department of BiologicalScience and Technology University of Tokushima Graduate School Japan Keywords cathepsin B cotyledon cysteine protease germination occluding loop Correspondence A. Tsuji Department of BiologicalScience and Technology University of Tokushima Graduate School 2-1 Minamijosanjima Tokushima 770-8506 Japan Fax 81 88 655 3161 Tel 81 88 656 7526 E-mail tsuji@ Received 29 July 2008 revised 1 September 2008 accepted 5 September 2008 doi Plant cathepsin B-like cysteine protease CBCP plays a role in disease resistance and in protein remobilization during germination. The ability of animal cathepsin B to function as a dipeptidyl carboxypeptidase has been attributed to the presence of a dihistidine His110-His111 motif in the occluding loop which represents a unique structure of cathepsin B. However a dihistidine motif is not present in the predicted sequence of the occluding loop of plant CBCP as determined from cDNA sequence analysis and the loop is shorter. In an effort to investigate the enzymatic properties of plant CBCP which possesses the unusual occluding loop we have purified CBCP from the cotyledons of daikon radish Raphanus sativus by chromatography through Sephacryl S-200 DEAE-cellulose hydroxyapatite and organomercurial-Sepharose. The molecular mass of the enzyme was estimated to be 28 kDa by SDS PAGE under reducing conditions. The best synthetic substrate for CBCP was t-butyloxycarbonyl Leu-Arg-Arg-4-methylcoumaryl 7-amide as is the case with human cathepsin B. However the endopeptidase activity of CBCP towards glucagon and adrenocorticotropic hormone showed broad cleavage specificity. Human cathepsin B preferentially cleaves model peptides via its dipeptidyl .