D-tyrosine

β-Cyclodextrin (β-CD) modified silver nanoparticles (AgNPs), denoted as β-CD/AgNPs, were prepared by a simple one-pot method. Due to the inherent chirality of β-CD, the developed β-CD/AgNPs exhibited higher affinity toward l-tyrosine (l-Tyr) than d-tyrosine (d-Tyr), leading to serious aggregation of AgNPs in the presence of l-Tyr. Consequently, the l-Tyr induced aggregation of AgNPs can result in signal amplification in the differential pulse voltammograms (DPVs) of l-Tyr, which can be applied for the electrochemical chiral discrimination of the Tyr enantiomers...

An analytical method for the simultaneous determination of chiral thyroxine and the related iodinated chiral compounds using LC-MS/MS is introduced in this study. D-Thyroid hormones (THs), which are not commercially available, were produced through the racemization reaction of the L-THs in acetic acid solution containing salicylaldehyde. The solution containing D- and L-THs after the reaction was used for optimizing the chiral separation. The D- and L-THs were well separated enantiomerically under isocratic conditions in 70 % acetonitrile containing 0...

Control over the photophysical properties and molecular organization of π-conjugated oligothiophenes is essential to their use in organic electronics. Herein we synthesized and characterized a variety of anionic pentameric oligothiophenes with different substitution patterns of L- or D-tyrosine at distinct positions along the thiophene backbone. Spectroscopic, microscopic, and theoretical studies of L- or D-tyrosine substituted pentameric oligothiophene conjugates revealed the formation of optically active π-stacked self-assembled aggregates under acid conditions...

OBJECTIVE: Our aim was to assess the anti-biofilm ability of previously unverified individual D-amino acids (DAAs), to produce plasma polymer encapsulated DAAs (PPEDAAs), to measure the shell thickness and subsequent release of DAAs, and to assess the effects of PPEDAAs on Enterococcus faecalis biofilms. MATERIALS AND METHODS: Microtitre tray assays were used to evaluate the effect of individual DAAs (D-leucine, D-methionine, D-tryptophan, and D-tyrosine) on E. faecalis biofilms of different maturity...

Biocides are widely used for the mitigation of microbial contamination, especially in the field of the aviation fuel industry. However, the long-term use of biocide has raised the concerns regarding the environmental contamination and microbial drug resistance. In this study, the effect of a mixture of D-amino acids (D-tyrosine and D-methionine) on the enhancement of the bactericidal effect of 5-Chloro-2-Methyl-4-isothiazolin-3-one/2-Methyl-2H-isothiazole-3-one (CMIT/MIT) against corrosive Vibrio harveyi biofilm was evaluated...

Tyrosinase starts melanogenesis and determines its course, catalyzing the oxidation by molecular oxygen of tyrosine to dopa, and that of dopa to dopaquinone. Then, nonenzymatic coupling reactions lead to dopachrome, which evolves toward melanin. Recently, it has been reported that d-tyrosine acts as tyrosinase inhibitor and depigmenting agent. The action of tyrosinase on the enantiomers of tyrosine (l-tyrosine and d-tyrosine) and dopa (l-dopa and d-dopa) was studied for the first time focusing on quantitative transient phase kinetics...

Terrestrial plants have C-to-U RNA editing in the transcripts of plastids and mitochondria. Target specificity for more than several hundred editing sites are governed by PLS (PPR, Long and Short) class Pentatricopeptide repeat (PPR) proteins with additional C-terminal domains. Half of these PPR proteins have DYW (Aspartate (D), Tyrosine (Y) and Tryptophan (W)) domains, which most likely harbour cytidine deaminase activity. The other half of them, E subclass and E+ subclass proteins, contain no or only a part of the DYW domain...

D-tyrosine is known to negatively regulate melanin synthesis by inhibiting tyrosinase activity. Here, we further reveal that peptides containing terminal D-tyrosine can reduce the melanin contents of human melanocytes. The addition of D-tyrosine to the terminus of the commercial anti-wrinkle peptide, pentapeptide-18 endowed the peptide with the ability to reduce the melanin content and tyrosinase activity in human MNT-1 melanoma cells and primary melanocytes. Consistently, terminal D-tyrosine-containing pentapeptide-18 inhibited the melanogenesis induced by α-MSH treatment or UV irradiation of MNT-1 cells and reduced melanin synthesis in the epidermal basal layer of a 3D human skin model...

Nanoscale biological assemblies exemplified by exosomes, endosomes and capsids, play crucial roles in all living systems. Supraparticles (SP) from inorganic nanoparticles (NPs) replicate structural characteristics of these bioassemblies, but it is unknown whether they can mimic their biochemical functions. Here, we show that chiral ZnS NPs self-assemble into 70-100 nm SPs that display sub-nanoscale porosity associated with interstitial spaces between constituent NPs. Similarly to photosynthetic bacterial organelles, these SPs can serve as photocatalysts, enantioselectively converting L- or D-tyrosine (Tyr) into dityrosine (diTyr)...

The work describes a voltammetric method for the recognition of tryptophan (Trp) enantiomers. A glassy carbon electrode (GCE) was modified with polydopamine-coated multiwalled carbon nanotubes and subsequently loaded with copper(II) ions. The morphology and structure of the material were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and electrochemical methods. The recognition of Trp enantiomers by the modified GCE was investigated by differential pulse voltammetry...

Neurotensin (NT) (pGlu-Leu-Tyr-Glu-Asn-Lys-Pro-Arg-Arg-Pro-Tyr-Ile-Leu) exerts a dual function as a neurotransmitter/neuromodulator in the central nervous system and as a hormone/cellular mediator in periphery. This dual function of NT establishes a connection between brain and peripheral tissues that renders this peptide a central player in energy homeostasis. Many biological actions of NT are mediated through its interaction with three types of NT receptors (NTS receptors). Despite its role in energy homeostasis, NT has a short half-life that hampers further determination of the biological actions of this peptide and its receptors in brain and periphery...

Biofilms formed by pathogenic bacteria are one of the most important reasons for multidrug resistance. One of the major limitations in the biofilm treatment is the existence of intensive matrices, which greatly block the diffusion of antimicrobial agents. In the current study, we designed poly(aspartamide)-derived micelles self-assembled from cationic copolymers with azithromycin-conjugated and pH-sensitive copolymers, followed by loading cis-aconityl-d-tyrosine (CA-Tyr) via electrostatic interactions. In response to the acidic microenvironment of the biofilm matrix, the hydrophilic transition of the pH-sensitive copolymers and the removal of CA-Tyr led to a sharp decrease in micelle size from 107 nm to 54 nm and a rapid shift in their zeta potential from -11...

Sorption of l- and d-Tyrosine (Tyr) from aqueous solutions on chiral membranes of chitosan (CH) was studied. A high adsorption in the membrane, with a marked enantioselectivity to l-Tyr, was found. Computational calculations carried out by docking and molecular dynamics (MD) showed a difference in the affinity of the enantiomers and two regions of adsorption in the polymer matrix. The interactions of the enantiomers with the polymer matrix were studied by using FTIR, DRx, DSC and TG measurements. These results indicate that adsorption of Tyr reduces the crystallinity of the membrane and generates a rearrangement of the chains, decreasing the intercatenary spacing...

Electrochemical enantiorecognition has attracted much interest due to its advantages of low cost and simple equipment. In this work, a new chiral ionic liquid is prepared and applied as an electrolyte for the one-step synthesis of functional graphene sheets (GO-(S,S)-CIL). More importantly, an electrode is modified by the material for the construction of an electrochemical sensor (GO-(S,S)-CIL-GCE). Enantiomers including L/D-tryptophan, (R)-/(S)-mandelic acid, (R)-/(S)-malic acid, and L/D-tyrosine are successfully distinguished by GO-(S,S)-CIL-GCE in the response of peak currents to different forms...

Cryptophycins are naturally occurring cytotoxins with great potential for chemotherapy. Since targeted therapy provides new perspectives for treatment of cancer, new potent analogues of cytotoxic agents containing functional groups for conjugation to homing devices are required. We describe the design, synthesis and biological evaluation of three new unit B cryptophycin analogues. The O -methyl group of the unit B D-tyrosine analogue was replaced by an O- (allyloxyethyl) moiety, an O- (hydroxyethyl) group, or an O- (((azidoethoxy)ethoxy)ethoyxethyl) substituent...

Aminoacyl-tRNA-synthetases are crucial enzymes for initiation step of translation. Possessing editing activity, they protect living cells from misincorporation of non-cognate and non-proteinogenic amino acids into proteins. Tyrosyl-tRNA synthetase (TyrRS) does not have such editing properties, but it shares weak stereospecificity in recognition of d-/l-tyrosine (Tyr). Nevertheless, an additional enzyme, d-aminoacyl-tRNA-deacylase (DTD), exists to overcome these deficiencies. The precise catalytic role of hydroxyl groups of the tRNATyr A76 in the catalysis by TyrRS and DTD remained unknown...

BACKGROUND: Photodynamic therapy (PDT) has been determined to be a promising treatment modality in the most resistant tumors such as malignant melanoma. However, the key cytotoxic agent of PDT, -singlet oxygen (1 O2 ) - represents a high risk of photodynamic-associated side effects e.g. skin photosensitization. Recently, controllable photosensitization, where 1 O2 is produced on demand, has received increasing attention. In our study, this could be achieved via loading the photosensitizer (PS) in nanoparticles (NPs) decorated with target-specific moieties characterized by 1 O2 quenching abilities to specifically locate the PS in the targeted cells and assure that 1 O2 is only produced where desired after cellular processing...

INTRODUCTION: Radiolabeled, low-molecular-weight prostate-specific membrane antigen (PSMA) inhibitors based on the Glu-ureido pharmacophore show promise for the detection and treatment of castration-resistant prostate cancer; however, high renal retention of activity, related in part to overexpression of PSMA in kidneys can be problematic. The goal of the current study was to investigate the use of brush border enzyme-cleavable linkers as a strategy for reducing kidney activity levels from radiolabeled PSMA inhibitors...

AIM AND PURPOSE: Biofilms in dental unit waterlines (DUWLs) are extremely difficult to eliminate. Aim of this study is to evaluate the efficacy of a mixture of four D-amino acids on biofilm dispersion in DUWLs. MATERIALS AND METHODS: A mixture of four D-amino acids (D-methionine, D-tryptophan, D-leucine, and D-tyrosine, 10 mM each), distilled water (control), and 0.1 M hydrochloric acid (HCl) was used in the experiment. In laboratory, pieces of DUWLs covered with biofilms were submerged in different solutions for 5 days, flushed, and measured OD600 of the dispersed biofilms...

The α- and β-class carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae, VchCAα, and VchCAβ, were investigated for their activation with natural and non-natural amino acids and amines. The most effective VchCAα activators were L-tyrosine, histamine, serotonin, and 4-aminoethyl-morpholine, which had KA s in the range of 8.21-12.0 µM. The most effective VchCAβ activators were D-tyrosine, dopamine, serotonin, 2-pyridyl-methylamine, 2-aminoethylpyridine, and 2-aminoethylpiperazine, which had KA s in the submicromolar - low micromolar range (0...