Chelidocystatin, a novel phytocystatin from Chelidonium majus.
Greater celandine (Chelidonium majus L.) has traditional uses in European and Chinese herbal medicine. In the plant sap significant inhibitory activity against papain was observed. A cysteine proteinase inhibitor, named chelidocystatin, was isolated from the plant using papain Sepharose affinity chromatography followed by gel filtration and ion-exchange chromatography. Chelidocystatin showed a M(r) of 10,000 on SDS-PAGE with the pI of 9.3, and was a strong inhibitor of cathepsin L (Ki = 5.6 x 10(-11) M), papain (Ki = 1.1 x 10(-10) M) and cathepsin H (Ki = 7.5 x 10(-9) M). The complete amino acid sequence of the protein was obtained with N-terminal sequencing and sequencing of the peptides after digestion of the protein. Moreover, a major part of the sequence was verified by molecular cloning. The conserved glycine residue at the N-terminal region and the QVVAG motif, which are both believed to be involved in the inhibitory activity, indicate that it is a member of the cystatin superfamily. The amino acid sequence of chelidocystatin shows a high degree of homology with cysteine proteinase inhibitors belonging to the phytocystatin group, especially with the recently described carrot and sunflower phytocystatins with which it shares 57% and 54% homology, respectively.
Rogelj
B
B
Department of Biochemistry and Molecular Biology, Institute Jozef Stefan, Jamova, Ljubljana, Slovenia.
Popovic
T
T
Ritonja
A
A
Strukelj
B
B
Brzin
J
J
D000595:Amino Acid Sequence; D056655:Cathepsin H; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000737:chemistry; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D015891:Cystatins / Q000737:chemistry / Q000302:isolation & purification*; D003546:Cysteine Endopeptidases / Q000737:chemistry; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases; D006801:Humans; D008969:Molecular Sequence Data; D010946:Plants, Medicinal / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; C116553:chelidocystatin; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; C534126:CTSH protein, human; D056655:Cathepsin H