[en] New complex compound with tryptophane of the complexes [Zn(trp)₂(H₂O)₂] were synthesized. It is shown that the composition of the complex obtained depends on the ratio of the initial components. The composition and structure of the complex were studied by elemental analysis, IR, X-ray phase analysis and thermogravimetric analysis. The method of IR spectroscopy showed that the ligand in the complex of the metal (II) complexes enter the neutral form and coordinate with the complexing agent through the nitrogen atom. The results of thermogravimetric studies have shown that the final product of the thermal decomposition of all compounds is metal oxide, respectively. The effect of the zinctryptophan complex (Zn-trf) on the biosynthesis of photosynthetic pigments and morphological parameters of seedlings of irradiated wheat seeds was studied. Initial experiments showed that, when treated seeds with the (Zn-trf) complex, their resistance to gamma rays is increased. On the basis of the data obtained, it can be concluded that the complex (Zn-trf) has radio protective properties

[en] Fluorescence studies of transthyretin (TTR) were conducted to detect structural changes associated with the environment of its two tryptophans, induced by binding of thyroxine (T₄). Non-radiative tryptophans relaxation rate has an activation energy of 6.4 kcal/mol for TTR, which is decreased to 4.4 kcal/mol for TTR-T₄ complex. The maximum fluorescence wavelength was red-shifted as the excitation wave-length was increased. T₄ changed the magnitude of this shift. T₄ binding per se changed the emission maximum reflecting different environments of the tryptophans. Double-quenching experiments also showed that T₄ produces changes in the tryptophans environments. These findings were interpreted as the result of structural alterations in the protein matrix induced by T₄ which contribute in part to explain the negative cooperativity associated with the occupancy of the second binding site. (author). 19 refs.; 3 figs.; 1 tab

[en] As a result of the reaction of tryptophan with copper (II) chloride, a complex of copper tryptophan ate was obtained. The composition of the complex was studied by elemental, thermal, Χ-ray phase analysis, IR, and UV spectroscopy. The anti radical activity of the complex was studied on irradiated wheat seeds. It was revealed that the treatment of wheat seeds before irradiation with an aqueous solution of complex leads to normalization of the biosynthesis of photosynthetic pigments.

No abstract available

[en] Highlights: • Recently reported purification scheme yields stable, unaggregated STARD1 preparations. • Interaction of STARD1 with fluorescent NBD-steroids depends on the NBD-group position. • The highest fluorescence response is detected for the cholesterol analogue 20NP. • 20NP binding stabilizes STARD1, leading to increased NBD fluorescence lifetime. • With a nM K_D, 20NP is promising for screening/identification of novel STARD1 ligands. Steroidogenic acute regulatory protein (StAR, STARD1) is a key factor of intracellular cholesterol transfer to mitochondria, necessary for adrenal and gonadal steroidogenesis, and is an archetypal member of the START protein family. Despite the common overall structural fold, START members differ in their binding selectivity toward various lipid ligands, but the lack of direct structural information hinders complete understanding of the binding process and cholesterol orientation in the STARD1 complex in particular. Cholesterol binding has been widely studied by commercially available fluorescent steroids, but the effect of the fluorescent group position on binding remained underexplored. Here, we dissect STARD1 interaction with cholesterol-like steroids bearing 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) group in different positions, namely, with 22-NBD-cholesterol (22NC), 25-NBD-cholesterol (25NC), 20-((NBDamino)-pregn-5-en-3-ol (20NP) and 3-(NBDamino)-cholestane (3NC). While being able to stoichiometrically bind 22NC and 20NP with high fluorescence yield and quantitative exhaustion of fluorescence of some protein tryptophans, STARD1 binds 25NC and 3NC with much lower affinity and poor fluorescence response. In contrast to 3NC, binding of 20NP leads to STARD1 stabilization and substantially increases the NBD fluorescence lifetime. Remarkably, in terms of fluorescence response, 20NP slightly outperforms commonly used 22NC and can thus be used for screening of various potential ligands by a competition mechanism in the future.

[en] The synthesis of selectively labeled [3-¹⁴C]-L-tryptophan and its derivative 5'-hydroxy-[3-¹⁴C]-L-tryptophan using chemical and multienzymatic methods is reported. The key intermediate for this synthesis, 3-¹⁴C]-DL-alanine was obtained from ¹⁴CH₃I as a result of its condensation with N- (diphenylmethylene)glycine tert-butyl ester. Next, the mixture containing [3-¹⁴C]-DL-alanine, indole or 5-hydroxyindole has been converted to [3-¹⁴C]-L-tryptophan or 5'-hydroxy-[3-¹⁴C]-L-tryptophan, respectively, in a one-pot multienzymatic reaction using four enzymes: -amino acid oxidase, catalase, glutamic-pyruvic transaminase and tryptophanase. (author)

[en] Highlights: • S31W and R145W introduce an extra fluorophore in βB2-crystallin. • S31W and R145W destabilize βB2-crystallin and promote thermal aggregation. • S31W accelerates but R145W retards UV-induced aggregation of βB2-crystallin. • The number of Trp fluorophores in β/γ-crystallin is evolutionarily optimized. β/γ-Crystallins are predominant structural proteins in vertebrate lens with unique properties of extremely high solubility, long-term stability and resistance to UV damage. Four conserved Trp residues in β/γ-crystallins account for UV absorbance and thereafter fluorescence quenching to avoid photodamage. Herein we found that βB2-crystallin Trp fluorescence was greatly enhanced by the introduction of an extra unquenched Trp fluorophore by cataract-associated mutations S31W and R145W. Both mutations impaired oligomerization, decreased stability and promote thermal aggregation, while S31W was more deleterious. S31W accelerated βB2-crystallin aggregation under UV damaging conditions, whereas R145W delayed. These observations suggested that the introduction of an extra Trp fluorophore had complicated effects on βB2-crystallin stability and aggregation against various stresses. Our findings highlight that the number of Trp fluorophores in β/γ-crystallin is evolutionarily optimized to exquisitely perform their structural roles in the lens.

No abstract available

[en] Eurosids basically evolved from the core Eudicots Rosids. The Rosids consist of two large assemblages, Eurosids I (Fabids) and Eurosids II (Malvids), which belong to the largest group of Angiosperms, comprising of >40,000 and ∼ 15,000 species, respectively. Although the evolutionary patterns of the largest class of disease resistance genes consisting of a nucleotide binding site (NBS) and leucine-rich repeats (LRRs) have been studied in many species, systemic research of NBS-encoding genes has not been performed in different orders of Eurosids II. Here, five Eurosids II species, Gossypium raimondii, Theobroma cacao, Carica papaya, Citrus clementina, and Arabidopsis thaliana, distributing in three orders, were used to gain insights into the evolutionary patterns of the NBS-encoding genes. Our data showed that frequent copy number variations of NBS-encoding genes were found among these species. Phylogenetic tree analysis and the numbers of the NBS-encoding genes in the common ancestor of these species showed that species-specific NBS clades, including multi-copy and single copy numbers are dominant among these genes. However, not a single clade was found with only five copies, which come from all of the five species, respectively, suggesting rapid turn-over with birth and death of the NBS-encoding genes among Eurosids II species. In addition, a strong positive correlation was observed between the Toll/interleukin receptor (TIR)) type NBS-encoding genes and species-specific genes, indicating rapid gene loss and duplication. Whereas, non- TIR type NBS-encoding genes in these five species showed two distinct evolutionary patterns. (author)

[en] Highlights: • Most Class A GPCRs contain a conserved WxFG motif. • Substitution of the W with a non-aromatic amino acid disrupts GPCR functioning. • Disrupted GPCR functioning is the due to aberrant plasma membrane localization. G protein-coupled receptors are the largest superfamily of cell surface receptors in the Metazoa and play critical roles in transducing extracellular signals into intracellular responses. This action is mediated through conformational changes in the receptor following ligand binding. A number of conserved motifs have critical roles in GPCR function, and here we focus on a highly conserved motif (WxFG) in extracellular loop one (EL1). A phylogenetic analysis documents the presence of the WxFG motif in ∼90% of Class A GPCRs and the motif is represented in 17 of the 19 Class A GPCR subfamilies. Using site-directed mutagenesis, we mutagenized the conserved tryptophan residue in eight receptors which are members of disparate class A GPCR subfamilies from different taxa. The modification of the Drosophila leucokinin receptor shows that substitution of any non-aromatic amino acid for the tryptophan leads to a loss of receptor function. Additionally, leucine substitutions at this position caused similar signaling defects in the follicle-stimulating hormone receptor (FSHR), Galanin receptor (GALR1), AKH receptor (AKHR), corazonin receptor (CRZR), and muscarinic acetylcholine receptor (mACHR1). Visualization of modified receptors through the incorporation of a fluorescent tag revealed a severe reduction in plasma membrane expression, indicating aberrant trafficking of these modified receptors. Taken together, these results suggest a novel role for the WxFG motif in GPCR trafficking and receptor function.