PARACEST properties of a dinuclear neodymium(III) complex bound to DNA or carbonate.
PARACEST properties of a dinuclear neodymium(III) complex bound to DNA or carbonate.
复制标题
与 DNA 或碳酸盐结合的双核钕 (III) 复合物的 PARACEST 特性。
DOI：
10.1021/bc900146z
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发表时间：
2009
影响因子：
4.7
通讯作者：
Morrow,JanetR
中科院分区：
文献类型：
--
作者：
Nwe,Kido;Andolina,ChristopherM;Huang,Ching-Hui;Morrow,JanetR
A dinuclear Nd(III) macrocyclic complex of1(1,4-bis[1-(4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane]-p-xylene) and mononuclear complexes of 1,4,7-tris-1,4,7,10-tetraazacyclododecane,2, and 1,4,7-tris[(N-N-diethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane,3, are prepared. Complexes of1and2give rise to a PARACEST (paramagnetic chemical exchange saturation transfer) peak from exchangeable amide protons that resonate approximately 12 ppm downfield from the bulk water proton resonance. The dinuclear Nd(III) complex is promising as a PARACEST contrast agent for MRI applications, because it has an optimal pH of 7.5 and the rate constant for amide proton exchange (2700 s−1) is nearly as large as it can be within slow exchange conditions with bulk water. Dinuclear Ln2(1) complexes (Ln(III) = Nd(III), Eu(III)) bind tightly to anionic ligands including carbonate, diethyl phosphate, and DNA. The CEST amide peak of Nd2(1) is enhanced by certain DNA sequences that contain hairpin loops, but decreases in the presence of diethyl phosphate or carbonate. Direct excitation luminescence studies of Eu2(1) show that double-stranded and hairpin-loop DNA sequences displace one water ligand on each Eu(III) center. DNA displaces carbonate ion despite the low dissociation constant for the Eu2(1) carbonate complex (Kd= 15 μM). Enhancement of the CEST effect of a lanthanide complex by binding to DNA is a promising step toward the preparation of PARACEST agents containing DNA scaffolds.
