title: Structure-function relationship of trichosanthin.
abstract: Trichosanthin (TCS), a 27 kDa ribosome inactivating protein extracted from the root tuber of Trichosanthes plant, was subjected to limited chymotrypsin digestion and three peptide fragments designated TCS-F1 72-247, TCS-F2 100-247, and TCS-F3 133-247 were generated. The RNA-N-glycosidase and cytotoxic activities of the TCS fragments were compared with that of inact TCS. TCS-F1 and TCS-F2 were biologically active, while TCS-F3 was completely inactive. Dose-dependent studies showed that TCS-F1 and TCS-F2 were less potent in their trophoblast cytotoxicity than intact TCS, however, full biological effect could still be obtained with a higher dosage. Based on the known three-dimensional structure of TCS, we postulate that the putative active site of TCS is located at amino acid residues 110 to 174.
authors.affiliation: Shanghai Institute of Cell Biology, Academia Sinica, China.
authors.forename: Y B
authors.initials: YB
authors.lastname: Ke
authors.forename: J K
authors.initials: JK
authors.lastname: Chen
authors.forename: H L
authors.initials: HL
authors.lastname: Nie
authors.forename: X H
authors.initials: XH
authors.lastname: He
authors.forename: X Y
authors.initials: XY
authors.lastname: Ke
authors.forename: Y H
authors.initials: YH
authors.lastname: Wang
mesh_terms: D002918:Chymotrypsin / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D010446:Peptide Fragments / Q000737:chemistry; D010449:Peptide Mapping; D013329:Structure-Activity Relationship; D015978:Trichosanthin / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D010446:Peptide Fragments; D015978:Trichosanthin; D002918:Chymotrypsin