DataSheet1.PDF

• Main Authors: Alexander Wurzer, Adrienn Vágner, Dávid Horváth, Flóra Fellegi, Hans-Jürgen Wester, Ferenc K. Kálmán, Johannes Notni
• Format: Dataset
• Language: unknown
• Published: 2018
• Subjects: Biochemistry; Environmental Chemistry; Geochemistry; Organic Chemistry; Inorganic Chemistry; Nuclear Chemistry; Medical Biochemistry: Proteins and Peptides (incl. Medical Proteomics); Medical Biochemistry and Metabolomics not elsewhere classified; Food Chemistry and Molecular Gastronomy (excl. Wine); Analytical Biochemistry; Cell Neurochemistry; Enzymes; Electroanalytical Chemistry; Analytical Chemistry not elsewhere classified; Organic Green Chemistry; Physical Organic Chemistry; Catalysis and Mechanisms of Reactions; Environmental Chemistry (incl. Atmospheric Chemistry); Huisgen-reaction; potentiometry; spectrophotometry; phosphinate; radiopharmaceuticals; endoradiotherapy; prostate-specific membrane antigen; theranostics; Carbonic acid
• Online Access: https://doi.org/10.3389/fchem.2018.00107.s001; https://figshare.com/articles/DataSheet1_PDF/6119567

Due to its 4 carbonic acid groups being available for bioconjugation, the cyclen tetraphosphinate chelator DOTPI, 1,4,7,10-tetraazacyclododecane-1,4,7, 10-tetrakis[methylene(2-carboxyethylphosphinic acid)], represents an ideal scaffold for synthesis of tetrameric bioconjugates for labeling with radiolanthanides, to be applied as endoradiotherapeuticals. We optimized a protocol for bio-orthogonal DOTPI conjugation via Cu(I)-catalyzed Huisgen-cycloaddition of terminal azides and alkynes (CuAAC), based on the building block DOTPI(azide) 4 . A detailed investigation of kinetic properties of Cu(II)-DOTPI complexes aimed at optimization of removal of DOTPI-bound copper by transchelation. Protonation and equilibrium properties of Ca(II)-, Zn(II), and Cu(II)-complexes of DOTPI and its tetra-cyclohexylamide DOTPI(Chx) 4 (a model for DOTPI conjugates) as well as kinetic inertness (transchelation challenge in the presence of 20 to 40-fold excess of EDTA) were investigated by pH-potentiometry and spectrophotometry. Similar stability constants of Ca II -, Zn II , and Cu II -complexes of DOTPI (logK (CaL) = 8.65, logK (ZnL = 15.40, logK (CuL) = 20.30) and DOTPI(Chx) 4 (logK (CaL) = 8.99, logK (ZnL) = 15.13, logK (CuL) = 20.42) were found. Transchelation of Cu(II)-complexes occurs via proton-assisted dissociation, whereafter released Cu(II) is scavenged by EDTA. The corresponding dissociation rates [k d = 25 × 10 −7 and 5 × 10 −7 s −1 for Cu(DOTPI) and Cu(DOTPI(Chx) 4 ), respectively, at pH 4 and 298 K] indicate that conjugation increases the kinetic inertness by a factor of 5. However, demetallation is completed within 4.5 and 7.2 h at pH 2 and 25°C, respectively, indicating that Cu(II) removal after formation of CuAAC can be achieved in an uncomplicated manner by addition of excess H 4 EDTA. For proof-of-principle, tetrameric DOTPI conjugates of the prostate-specific membrane antigen (PSMA) targeting motif Lys-urea-Glu (KuE) were synthesized via CuAAC as well as dibenzo-azacyclooctine (DBCO) based, strain-promoted click ...