741677-99-6Relevant academic research and scientific papers
Synthesis and characterization of a cell-permeable bimodal contrast agent targeting β-galactosidase
Keliris, Aneta,Ziegler, Thomas,Mishra, Ritu,Pohmann, Rolf,Sauer, Martin G.,Ugurbil, Kamil,Engelmann, J?rn
, p. 2529 - 2540 (2011/06/17)
Noninvasive monitoring of intracellular targets such as enzymes, receptors, or mRNA by means of magnetic resonance imaging (MRI) is increasingly gaining relevance in various research areas. A vital prerequisite for their visualization is the development of cell-permeable imaging probes, which can specifically interact with the target that characterizes the cellular or molecular process of interest. Here, we describe a dual-labeled probe, Gd-DOTA-k(FR)-Gal-CPP, designed to report the presence of intracellular β-galactosidase (β-gal) enzyme by MRI. This conjugate consists of a galactose based core serving as cleavable spacer, incorporated between the cell-penetrating peptide D-Tat49-57 and reporter moieties (Gd-DOTA, fluorescein (FR)). We employed a facile building block approach to obtain our bimodal probe, Gd-DOTA-k(FR)-Gal-CPP. This strategy involved the preparation of the building blocks and their subsequent assembly using Fmoc-mediated solid phase synthesis, followed by the complexation of ligand 14 with GdCl 3. Gd-DOTA-k(FR)-Gal-CPP showed a considerably higher relaxivity enhancement (16.8 ± 0.6 mM-1 s-1, 123 MHz, ～21 °C) relative to the commercial Gd-DOTA (4.0 ± 0.12 mM-1 s-1, 123 MHz, ～21 °C). The activation of Gd-DOTA-k(FR)-Gal- CPP was based on a cellular retention strategy that required enzymatic cleavage of the delivery vector from galactose moiety following the cell internalization to achieve a prolonged accumulation of the reporter components (Gd-DOTA/FR) in the β-gal expressing cells. Cellular uptake of Gd-DOTA-k(FR)-Gal-CPP in β-gal expressing C6/LacZ and enzyme deficient parental C6 rat glioma cells was confirmed by fluorescence spectroscopy, MR imaging and ICP-AES measurements. All methods showed higher accumulation of measured reporters in C6/LacZ cells compared to enzyme deficient parental C6 cells. Fluorescence microscopy of cells labeled with Gd-DOTA-k(FR)-Gal-CPP indicated a predominantly vesicular localization of the green fluorescent conjugate around cell nuclei. This cellular distribution was most likely responsible for the observed non-specific background signal in the enzyme deficient C6 cells. Even though the specific accumulation of our bimodal probe has to be further improved, it could be already used for cell imaging by MRI and optical modalities.
Rational design, synthesis, and characterization of novel inhibitors for human β1,4-galactosyltransferase
Takaya, Kenji,Nagahori, Noriko,Kurogochi, Masaki,Furuike, Tetsuya,Miura, Nobuaki,Monde, Kenji,Lee, Yuan Chuan,Nishimura, Shin-Ichiro
, p. 6054 - 6065 (2007/10/03)
An affinity labeling reagent, uridine 5′-(6-amino-{2-[(7-bromomethyl- 2-naphthyl)methoxycarbonylmethoxy]ethoxy}acetyl-6-deoxy-α-D- galactopyranosyl) diphosphate (1a), was designed on the basis of 3D docking simulation and synthesized to investigate the functional role of Trp310 residue located in the small loop near the active site of human recombinant galactosyltransferase (βGalT-1). Mass spectrometric analysis revealed that the Trp310 residue of βGalT1 can be selectively modified with the naphthylmethyl group of compound 1a at the C-3 position of the indole ring. This result motivated us to synthesize novel uridine-5′-diphosphogalactose (UDP-Gal) analogues as candidates for mechanism-based inhibitors for βGalT-1. We found that uridine 5′-(6-O-[10-(2-naphthyl)-3,6,9- trioxadecanyl]-α-D-galactopyranosyl) diphosphate (2) is the strongest inhibitor (Ki = 1.86 μM) against UDP-Gal (Km, = 4.91 μM) among compounds reported previously. A cold spray ionization time-of-flight mass spectrometry study demonstrated that the complex of this inhibitor and βGalT-1 cannot interact with an acceptor substrate in the presence of Mn2+.
