Synthesis and characterization of two (111)In-labeled DTPA-peptide conjugates.
This report describes the synthesis and characterization of two (111)In-labeled DTPA-peptide conjugates (DTPA-MA and DTPA-BA). It is surprising to find that (111)In(DTPA-MA) and (111)In(DTPA-BA) are more hydrophilic than their corresponding (90)Y analogues, suggesting a different coordination sphere in (111)In and(90)Y complexes of the same DTPA-peptide conjugate. By a reversed phase HPLC method, both (111)In(DTPA-MA) and (111)In(DTPA-BA) showed only one radiometric peak in their respective HPLC chromatogram due to a rapid interconversion of different isomers (particularly cis and trans isomers for (111)In(DTPA-MA); cis-cis, cis-trans, trans-cis, and trans-trans isomers for (111)In(DTPA-BA)). The interconversion of different isomers involves the "wagging" of the diethylenetriamine backbone, "shuffling" of the NO or NO(2) donor sets, and a rapid inversion at the terminal amine-nitrogen atoms.
Liu
S
S
Medical Imaging Division, DuPont Pharmaceuticals Company, 331 Treble Cove Road, North Billerica, Massachusetts 01862, USA. shuang.liu@dupontpharma.com
Edwards
D S
DS
D002851:Chromatography, High Pressure Liquid; D007205:Indium Radioisotopes / Q000737:chemistry*; D007536:Isomerism; D009942:Organometallic Compounds / Q000737:chemistry; D004369:Pentetic Acid / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry
D007205:Indium Radioisotopes; D009942:Organometallic Compounds; D010456:Peptides, Cyclic; C424782:cyclo(Arg-Gly-Asp-Phe-Lys)(2)DTPA; C424783:cyclo(Arg-Gly-Asp-Phe-Lys)DTPA; D004369:Pentetic Acid