Preparation of Red-Emitting Copper Nanoclusters Based on Penicillamine and Copper
Long, Tengfei, et al. Nanoscale, 2016, 8(18), 9764-9770.
Based on the complexation and redox reaction between copper (II) and penicillamine (Pen) enantiomers, a pair of optically active red-emitting copper nanoclusters (CuNCs) was successfully prepared. In this work, Pen acts as both a reducing agent and a stabilizing ligand. The obtained CuNCs exhibit unique aggregation-induced emission (AIE) properties and are candidates as pH stimulus-responsive functional materials. Furthermore, CuNCs show biomarking potential due to high photoluminescence (PL) quantum yield (QY) and significant cellular uptake.
Preparation of chiral CuNCs with penicillamine
· At room temperature, 100 μL of 150 mM CuCl2 and 3 ml of 25 mM D (L)-penicillamine were combined with 1.9 ml of deionized water. The solution initially appeared brown when the two substances were mixed, but quickly changed to a blue-violet color.
· After allowing the reaction to proceed for 2 hours, a milky precipitate formed and was separated by centrifugation at 9500 rpm (8029g) for 15 minutes. The isolated precipitate was then purified through repeated centrifugation and washing steps three times.
· Finally, the resulting products were freeze-dried under vacuum. The optically active CuNCs thus obtained were found to be stable in the solid state when stored in the refrigerator.
Inhibitory Effect of L-Penicillamine on Serine Palmitoyltransferase
Lowther, Jonathan, et al. MedChemComm, 2012, 3(8), 1003-1008.
Penicillamine (Pen) is a sulfur-containing, non-protein amino acid that is a degradation product of the hydrolysis of the β-lactam ring of all penicillins. Both D-Pen and L-Pen can interact with the vitamin cofactor pyridoxal-5-phosphate (PLP), but L-Pen is generally a better inhibitor of PLP-dependent enzymes. Serine palmitoyltransferase (SPT) is a PLP-dependent homodimeric enzyme that catalyzes the first step in de novo sphingolipid biosynthesis. The study shows that aminothiols that mimic L-Ser, the natural amino acid substrate of SPT, are mechanism-based inactivators of SPT with inhibition occurring by disabling of the PLP cofactor.
SPT activity assays following inactivation by aminothiols
· SPT activity was assessed through a DTNB assay. The assay included enzyme, substrates, and DTNB at final concentrations of 0.25 mM SpSPT, 25 mM L-serine, 250 mM palmitoyl-CoA, and 0.2 mM DTNB in 20 mM HEPES buffer with a pH of 8.0.
· Because aminothiols react instantaneously with DTNB, SPT samples inactivated by L-Pen were dialysed prior to activity measurements. Control SpSPT samples without inhibitor underwent the same dialysis process, and their rates were set as 100% relative activity.
· Each activity assay was conducted in duplicate, with error bars representing standard error of the mean (SEM) values from three separate inactivation experiments (n=3).
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