We demonstrate here that a nitrile-derivatized phenylalanine residue, p-cyanophenylalanine (PheCN), and tryptophan (Trp) constitute novel donor−acceptor pair for fluorescence resonance energy transfer (FRET). The Förster distance of this FRET was determined to be ∼16 Å hence is well suited determining relatively short separation distances. To validate the applicability in conformational studies, we studied heterogeneity 14-residue amphipathic peptide, Mastoparan X (MPx peptide), water 7 M...

The thermal stability and folding kinetics of a 15-residue β-hairpin (SESYINPDGTWTVTE) have been studied by using infrared (IR) spectroscopy coupled with laser-induced temperature-jump (T-jump) technique for rapid folding−unfolding initiation. An alternative method based on analyzing IR difference spectra was also introduced to obtain thermodynamic properties β-sheets, which complements the commonly used circular dichroism (CD) fluorescence techniques. Equilibrium measurements indicate that...

Abstract Recently, it is has been shown that the CN stretching vibration of a non‐natural amino acid, p ‐cyano‐phenylalanine (Phe CN ), could be used as an infrared reporter local environment. Here, we further showed fluorescence emission Phe also sensitive to solvent and, therefore, novel optical probe for protein binding and folding studies. Moreover, found quantum yield nearly five times larger than phenylalanine more importantly, can selectively excited even when other aromatic acids...

The photophysical properties of several 2-substituted, 10-alkylated phenothiazines were measured in solvents to investigate the relevance molecular structure their photophysics and consequent photochemistry. Because interaction modes each drug its corresponding species strongly depend on variety microenvironments cells, one these must also be determined separately understand fully mechanism action side effects. Information chemical interactions different at cellular level can inferred from...

Distinct local dynamics of Aβ_1–23 amyloid formation are characterized using an unnatural amino acid <italic>p</italic>-cyanophenylalanine as a spectroscopic probe.

α1-Antitrypsin (AT) is the most abundantly circulating human proteinase inhibitor in serpin family. The polymerization of AT, leading to α1-antitrypsin deficiency, has been studied extensively vitro by a variety ensemble methods. Here we report use fluorescence correlation spectroscopy gain further insight into this process. Measurements distributions diffusion times polymerizing carried out at 45, 50, and 55 °C, clearly show existence kinetic lag phase, during which short oligomers are...

Imipramine (IPA) and its derivatives are used widely for the treatment of depression other mental disorders. Although there more than 20 FDA-approved antidepressant drugs, search continues better compounds with fewer deleterious side effects higher efficacy. Over past decade, several classes antipsychotic drugs have been developed, whichin spite their structural diversityshare an ability to modulate neurotransmission produce undesirable effects. Phototoxicity is one most important noted in...

2-chlorothioxanthone (CTX) is used as photoinitiator for the reticulation of synthetic resins and preparation pharmaceuticals. It was previously determined that CTX primary photoproduct z-chlorprothixene (CPTX) when irradiated at 313 nm formed in an autocatalyzed reaction through energy-transfer mechanism (Piñero et al. [2009] Photochem. Photobiol., 85, 895-900). In this work, photophysical properties were measured acetonitrile/water solutions to determine if their magnitude can affect side...

Protein and peptide aggregation is an important issue both in vivo vitro. Herein, we examine the behaviors of two well-studied β-hairpins, Trpzip1 Trpzip2. Previous studies suggested that Trpzip2 remains monomeric up to a concentration ~15 mM whereas readily aggregates at micromolar concentrations acidic or neutral pH. This disparity puzzling considering these peptides differ only their turn sequences (i.e., GN vs NG). We hypothesize can aggregate from folded states via native edge-to-edge...

The electrical characterization and ammonia vapor (NH 3 ) response of a p‐Si/n‐poly[benzimidazobenzophenanthroline] (n‐BBL) thin‐film junction diode are reported. presence depletion layer at the n‐BBL/p‐Si interface is verified via capacitance–voltage measurements, built‐in potential ≈1.8 V. Using standard equation for data analysis, turn‐on voltage, rectification ratio, ideality parameter found to be 2 V, 16, 6, respectively. also tested in NH where it retained its asymmetric J – V behavior...

Abstract The mechanisms that trigger the phototoxic response to 2‐chlorophenothiazine derivatives are still unknown. To better understand relationship between molecular structure of halogenated phenothiazines and their activity, photophysics photochemistry were studied in several alcohols. photodestruction quantum yields determined under anaerobic conditions using monochromatic light (313 nm). Absorption‐ emission‐spectroscopy, 1 H‐ 13 C‐NMR GC‐MS used characterize photoproducts reference...

Abstract— Absorption and emission techniques were used to characterize the ground (S 0 ), singlet (S|) triplet states (T 1 ) of gilvocarcin V (GV) M (GM) in different solvents. Aggregation GV with dimerization constant equal 7800 −1 is observed 10% dimethyl‐sulfoxide (DMSO)/water. The photophysical properties S, state these molecules are more sensitive changes solvent characteristics than corresponding states. absorption visible light by GM results a higher dipole moment excited causing red...

The thermal stability and folding kinetics of a series 15-residue β-hairpins with common Type I [3:5] NPDG turn were studied using Fourier transform infrared spectroscopy (FTIR) laser-induced temperature jump (T-jump) detection, respectively. Mutations at positions 3, 5, or 13 in the peptide sequence SEXYXNPDGTWTXTE, where X represents position mutation, performed to study roles hydrophobic interactions determining thermodynamic kinetic properties β-hairpin folding. studies show broad...

The role of base sequence and conformation on the photochemistry photophysics thymidylyl (3'−5')-2'-deoxyadenosine sodium salt (TpdA) 2-deoxyadenylyl (3'−5')-thymidine ammonium (dApT) was studied. To this end, nanosecond transient absorption at 266 nm, steady-state irradiation 254 quantum chemical calculations were used. spectra show solvated electron broad band in visible region for each dinucleotide. In addition, low-intensity bands are observed UV region, which attributed to deprotonated...

Abstract Chlorprothixene (CPTX, Taractan ® ) is a low potency antipsychotic mainly used for the treatment of psychotic disorders ( e.g. schizophrenia) and acute mania occurring as part bipolar disorders. As in case other numerous drugs psychiatric disorders, CPTX presents geometric isomerism. Therefore, vitro irradiation induces rapid Z/E isomerization, which can affect its pharmacokinetic properties. This photoisomerization not dependent on oxygen concentration. The quantum yields...

Photophysical and electrochemical properties of protriptyline hydrochloride (PTL-HCl) its free base were measured in different solvents. Ground-state remain unchanged as a function solvent or protonation state. The fluorescence quantum yield lifetime, on the other hand, are solvent-dependent. Fluorescence lifetimes results obtained from monoexponential decay fittings. Characterization 266 nm nanosecond laser flash photolysis species reveals presence triplet−triplet transient intermediate at...

The transient absorption spectra of the intermediates produced by 355 nm laser excitation gilvocarcin derivatives have been investigated in various solvents. consist a triplet-triplet visible region and residual observed between 340 700 due to long-lived species, assigned radical cation. A broad-fast decaying band with maximum at around attributed solvated electron is also seen solutions containing low DMSO/water volume ratio 266 irradiation 50% methanol/water solvent mixture. molar...

Unwanted photoinduced responses are well-known adverse effects of most promazine drugs, including levomepromazine (LPZ, Levoprome(®) or Nozinan(®)). This drug is indicated in psychiatry primarily for the treatment schizophrenia and other schizoaffective disorders. Levomepromazine's particular sedative properties make it especially fit use psychiatric intensive care. Nevertheless, photolabile under UV-A UV-B light aerobic conditions resulting formation its sulfoxide. The LPZ photochemistry...