Sahlcheng4215

Photocleavable protecting groups (PPGs) play a pivotal role in numerous studies. They enable controlled release of small effector molecules to induce biochemical function. The number of PPGs attached to a variety of effector molecules has grown rapidly in recent years satisfying the high demand for new applications. However, until now molecules carrying PPGs have been designed to activate function only in a single direction, namely the release of the effector molecule. Herein, we present the new approach Two-PPGs-One-Molecule (TPOM) that exploits the orthogonal photolysis of two photoprotecting groups to first release the effector molecule and then to modify it to suppress its induced effect. The moiety resembling the tyrosyl side chain of the translation inhibitor puromycin was synthetically modified to the photosensitive ortho-nitrophenylalanine that cyclizes upon near UV-irradiation to an inactive puromycin cinnoline derivative. Additionally, the modified puromycin analog was protected by the thio-coumarylmethyl group as the second PPG. This TPOM strategy allows an initial wavelength-selective activation followed by a second light-induced deactivation. Both photolysis processes were spectroscopically studied in the UV/vis- and IR-region. In combination with quantum-chemical calculations and time-resolved NMR spectroscopy, the photoproducts of both activation and deactivation steps upon illumination were characterized. We further probed the translation inhibition effect of the new synthesized puromycin analog upon light activation/deactivation in a cell-free GFP translation assay. TPOM as a new method for precise triggering activation/deactivation of effector molecules represents a valuable addition for the control of biological processes with light.Although current LC-MS technology permits scientists to efficiently screen clinical samples in translational research, e.g., steroids, biogenic amines, and even plasma or serum proteomes, in a daily routine, maintaining the balance between throughput and analytical depth is still a limiting factor. A typical approach to enhance the proteome depth is employing offline two-dimensional (2D) fractionation techniques before reversed-phase nanoLC-MS/MS analysis (1D-nanoLC-MS). These additional sample preparation steps usually require extensive sample manipulation, which could result in sample alteration and sample loss. Here, we present and compare 1D-nanoLC-MS with an automated online-2D high-pH RP × low pH RP separation method for deep proteome profiling using a nanoLC system coupled to a high-resolution accurate-mass mass spectrometer. The proof-of-principle study permitted the identification of ca. 500 proteins with ∼10,000 peptides in 15 enzymatically digested crude serum samples collected from healthy donors in 3 laboratories across Europe. The developed method identified 60% more peptides in comparison with conventional 1D nanoLC-MS/MS analysis with ca. 4 times lower throughput while retaining the quantitative information. Serum sample preparation related changes were revealed by applying unsupervised classification techniques and, therefore, must be taken into account while planning multicentric biomarker discovery and validation studies. Overall, this novel method reduces sample complexity and boosts the number of peptide and protein identifications without the need for extra sample handling procedures for samples equivalent to less than 1 μL of blood, which expands the space for potential biomarker discovery by looking deeper into the composition of biofluids.We report on robust silk fibroin (SF) gels fabricated by incorporating cellulose nanocrystals (SF/CNC) as a "tough" unit and photopolymerization of acrylamide as an "elastic" segment. The addition of CNC affects the refolding process of SF molecules controlled by nucleation via templating, resulting in a stable mesoscopic structure. The gel shows robust mechanical stability (88.8% of initial stress after 1000 compression cycles) and excellent adhesion to various materials. The connected gel can recover its ionic conductivity within 20 s and be stretched to a maximum strain of 498% after healing for 10 h with an efficiency of 95.2%. This multifunctional gel sensor can sensitively detect different toxic gases and small-scale and large-scale human motions in real-time. Its sensitivity is calculated as GF = 3.84 at 0-200% strain. LY303366 Especially, the gel with 5 wt % thermochromic pigments as a visual temperature indicator can quickly reflect abnormal human body temperature according to the color change. Therefore, the strategy shows potential applications in flexible electrodes, biomimetic sensors, and visual biosensors.Methionine (Met) plays an important role in the metabolism of cisplatin anticancer drug. Yet, methionine platination in aqueous solution presents a highly complex pattern of interconnected paths and intermediates. This study reports on the reaction of methionine with the active aqua form of cisplatin, cis-[PtCl(NH3)2(H2O)]+, isolating the encounter complex of the reactant pair, cis-[PtCl(NH3)2(H2O)]+·Met, by electrospray ionization. In the unsolvated state, charged intermediates are characterized for their structure and photofragmentation behavior by IR ion spectroscopy combined with quantum-chemical calculations, obtaining an outline of the cisplatin-methionine reaction at a molecular level. To summarize the major findings (i) the cis-[PtCl(NH3)2(H2O)]+·Met encounter complex, lying on the reaction coordinate of the Eigen-Wilkins preassociation mechanism for ligand substitution, is delivered in the gas phase and characterized by IR ion spectroscopy; (ii) upon vibrational excitation, ligand exchange occurs within cis-[PtCl(NH3)2(H2O)]+·Met, releasing water and cis-[PtCl(NH3)2(Met)]+, along the calculated energy profile; (iii) activated cis-[PtCl(NH3)2(Met)]+ ions undergo NH3 departure, forming a chelate complex, [PtCl(NH3)(Met)]+, whose structure is congruent with overwhelming S-Met ligation as the primary coordination step. The latter process involving ammonia loss marks a difference with the prevailing chloride replacement in protic solvent, pointing to the effect of a low-polarity environment.