- Cadmium(II)-stimulated enzyme activation of Arabidopsis thaliana phytochelatin synthase 1
-
Phytochelatin (PC), a class of heavy metal-binding peptides, is synthesized from the tripeptide glutathione (GSH) and/or previously synthesized PC in a reaction mediated by PC synthase (PCS). In the present study, the PC production rate catalyzed by recombinant Arabidopsis PCS1 (rAtPCS1) in the presence of a constant free Cd(II) level increased steadily and the kinetic parameters were approximated using a substituted-enzyme mechanism in which GSH and bis(glutathionato)cadmium acted as co-substrates. In contrast, the PC production rate as a function of GSH concentration at a constant total Cd(II) concentration reached a maximum, which shifted toward higher GSH concentrations as the concentration of Cd(II) was increased. These observations are consistent with the suggestion that rAtPCS1 possesses a Cd(II) binding site where Cd(II) binds to activate the enzyme. The affinity constant, optimized using a one-site mathematical model, successfully simulated the experimental data for the assay system using lower concentrations of Cd(II) (5 or 10 μM) but not for the assay using higher concentrations (50 or 500 μM), where a sigmoidal increase in PCS activity was evident. Furthermore, the PCS activity determined at a constant GSH concentration as a function of Cd(II) concentration also reached a maximum. These findings demonstrate that rAtPCS1 also possesses a second Cd(II) binding site where Cd(II) binds to induce an inhibitory effect. A two-site mathematical model was applied successfully to account for the observed phenomena, supporting the suggestion that rAtPCS1 possesses two Cd(II) binding sites.
- Ogawa, Shinya,Yoshidomi, Takahiro,Yoshimura, Etsuro
-
-
Read Online
- Cosmetic Composition Comprising Phytochelatin
-
Provided are a cosmetic composition comprising phytochelatin, a product comprising the same, and a method for preparing the composition and/or product. The composition for external application for skin and/or cosmetic composition exhibits excellent antioxidant activity by containing phytochelatin, does not show skin cytotoxicity, is water-soluble, has excellent stability even when stored for a long time, and is excellent in protecting the skin from harmful substances.
- -
-
Paragraph 0042; 0053-0066
(2021/05/18)
-
- Conversion of Glutathione into Cadystins and Their Analogs Catalyzed by Carboxypeptidase Y
-
Cadystins induced in a fission yeast treated with Cd2+ are the higher homologs of glutathione. In the present work, glutathione was incubated with Carboxypeptidase Y at a high substrate concentration. The reaction afforded not only the degraded product, but also cadystins and their analogs. A possible transformation pathway for glutathione by this enzyme is proposed.
- Imai, Kunio,Obata, Hitoshi,Shimizu, Keisuke,Komiya, Takashi
-
p. 1193 - 1194
(2007/10/03)
-
- Solution Synthesis of Phytochelatins, Isopeptides from the Plant Kingdom
-
Phytochelatins which are linear peptide polymers of the γ-glutamylcysteine portion of glutathione with the general formula H-n-Gly-OH (n=2-11) are the main components for the detoxification of heavy metals in the plant kingdom.So far these peptides have been mostly obtained by isolation from cell suspension cultures.We have now prepared some of these (n=2-4) by the classical solution synthesis under mild conditions.For the protection of amino, carboxyl and thiol functions Nps, tBu and StBu protecting groups have been employed, respectively.The characterization of the peptide intermediates and final products has been achieved by mass spectrometry, 13C-NMR spectroscopy and amino acid analysis. Key Words: Phytochelatins / Isopeptide bond / Glutathione
- Zeng, Weiguang,Hemmasi, Bahram
-
p. 311 - 316
(2007/10/02)
-
- Synthesis of Metallothionein-like Peptides Cadystin A and B Occurring in a Fission Yeast, and Their Isomers
-
The unit peptides, cadystin A and B, in the cadmium-containing peptides occurring in a fission yeast were synthesized for conformation of the structure.Four possible stereoisomers of the previously proposed structure for cadystin were also synthesized.
- Kondo, Naoto,Isobe, Minoru,Imai, Kunio,Goto, Toshio
-
-
- CADYSTIN A AND B, MAJOR UNIT PEPTIDES COMPRISING CADMIUM BINDING PEPTIDES INDUCED IN A FISSION YEAST-----SEPARATION, REVISION OF STRUCTURES AND SYNTHESIS
-
The unit peptide, cadystin, of the cadmium-binding peptides occuring in a fission yeast was further separated into two major components, cadystin A and B, structures of which were determined to be 1 and 2, respectively, and confirmed by synthesis.The structure previously reported for cadystin was thus revised.
- Kondo, Naoto,Imai, Kunio,Isobe, Minoru,Goto, Toshio,Murasugi, Akira,et al.
-
p. 3869 - 3872
(2007/10/02)
-