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[en] Coordination compounds of α- and β-alanines with U(VI) and Th(IV) ions have been isolated. The formation of 1:1 and 1:2 (metal:ligand) complexes was identified in the case of uranyl ion while only 1:1 complexes were isolated with thorium ion. Elemental analysis, electrical conductance measurements, spectral measurements and IR spectral analysis were performed. The IR spectra showed that the ligands coordinate via the carboxylate and amino groups and revealed the presence of coordinated water molecules. (Auth.)
[en] To understand the role of cysteine (SH) residues in the folding of hen ovalbumin (OVA), SH-mutated OVAs, in which each SH residue was replaced by alanine (C11A, C30A, C367A, and C382A), were prepared. SDS-PAGE analysis under non-reducing conditions showed that the C11A and C30A mutants produced a disulfide (SS) isomer in addition to a protein with a native SS bond (Cys73–Cys120). The susceptibility to elastase digestion suggested that the Cys73 residue in the SS isomer participates as a counterpart of the SS bond. Upon refolding of the SH-mutated OVAs under the denatured and SS-reduced states, only C30A failed to refold into an intact form. This indicated that the Cys30 residue plays an important role in correct refolding. To confirm this, each of the four SH-mutated OVAs, in which the original SS-forming sites (C11/73/120A, C30/73/120A, C73/120/367A, and C73/120/382A) were deleted, was constructed and expressed. The C11/73/120A and C30/73/120A mutants formed no SS form, in contrast to C73/120A as a control. Thus, we concluded that Cys30 participates in the correct folding of OVA, and that its SS bond (Cys11–Cys30) is transiently generated during the early folding stage to avoid misfolding, and then the native SS form of OVA is regenerated through SH–SS exchanges.
[en] Ternary complexes of cadmium(II) with oxalate as primary ligand and α- and β-alanines as secondary ligands have been studied polarographically. Formation of three mixed complex species, [Cd(amino acid) (oxalate)], [Cd(amino acid) (oxalate)2] and [Cd(anino acid)2(oxalate)], is observed in each case. The reduction is reversible and diffusion-controlled. The stability constants have been evaluated usino the method of McMasters. The α-alanine complexes are found to be more stable than the corresponding β-alanine complexes. (author)
[en] A procedure for the asymmetric conversion of 2-deutero-3-fluoro-L-alanine into the corresponding D-isomer is given. The L-isomer is dissolved in an aqueous solution of a hydrogen halogenide and treated with sodium-nitrite. The then formed L-2-deutero-2-halo-3-fluoropropionic acid is heated with either NH3 or sodiumazide, and the 2-halogen is substituted by a 2-azido group which is catalytically hydrogenated to form the 2-deutero-3-fluoro-D-alanine. The compound has strong antibacterial properties
[en] A number of stable chemical radicals result following irradiation with ionizing rays of α-β-alanine and 4-hydroxyproline. They could be put into evidence using post-irradiation EPR technique. Analysis and inter-comparison of spectra signals become important for a correct assignment of structure and, subsequently of generating mechanisms in amino acids irradiated samples. (author)
[en] Highlights: • Amino-terminal 40 amino acids of HPIV3 P restrict and regulate N0-P interaction. • PA28P fails to support RNA synthesis of HPIV3 minigenome replicon. • Recombinant HPIV3 with mutation of A28P in P failed to be rescued. The phosphoprotein (P) of human parainfluenza virus type 3 (HPIV3) plays a pivotal role in viral RNA synthesis, which interacts with the nucleoprotein (N) to form a soluble N0-P complex (N0, free of RNAs) to prevent the nonspecific RNA binding and illegitimate aggregation of N. Functional regions within P have been studied intensively. However, the precise site (s) within P directly involved in N0-P interaction still remains unclear. In this study, using a series of deleted and truncated mutants of P of HPIV3, we demonstrate that amino-terminal 40 amino acids (aa) of P restrict and regulate N0-P interaction. Furthermore, using in vivo HPIV3 minigenome replicon assay, we identify a critical P mutant (PA28P) located in amino-terminal 40 aa, which fails to support RNA synthesis of HPIV3 minigenome replicon. Although PA28P maintains an enhanced N-P interaction, it is unable to form N0-P complex and keep N soluble, thus, resulting in aggregation and functional abolishment of N-P complex. Moreover, we found that recombinant HPIV3 with mutation of A28P in P failed to be rescued. Taken together, we identified a residue within the extreme amino-terminus of P, which plays a critical role in restricting the excessively N-P interaction and keeping a functional N0-P complex formation.
[en] CH3 C HCOOH is commonly accepted as the free radical responsible for the ESR signal detected in alanine after irradiation. The aim of this study is to find out the number of transient species leading to this radical and their kinetics of reaction. To do so, we follow the evolution of the ESR/alanine spectrum shape and correlate the response estimated from the central peak height to the absorbed dose. We use the theory of transformation systems. The first step is to make hypothesis on the number of equivalence classes and their content. From these hypotheses, we model the kinetics of free radical concentrations and check their fitting with experiment. We present comments on these different models, and their consequences on the evolution of the ESR signal on the first days after irradiation. The two successive reaction mechanisms (creation of free radicals and recombination reaction) are compared with the results obtained from a multiparametric study (experimental design) of combined effects (temperature and humidity before and after irradiation) which influence the reaction kinetics. (author)
[en] The proton ligand stability constants and stability constants of simple and mixed ligand chelates of uranyl ion with glycine, glycyl-glycine, mercaptopropionyl glycine, α-alanine, β-alanine, aspartic acid, glutamic acid, picolinic, nicotinic and isonicotinic acids have been studied potentiometrically at 25 ± 0.5 degC and μ = 0.1 M (NaClO4) in aqueous medium. Uranyl forms 1:1 and 1:2 complexes with all the chelating agents except in aspartic acid. The mixed ligand chelates are shown to have formed in simultaneous equilibria. The lower values of stability constants of mixed ligand chelates than the sum of the individual log stability constants of the first and second ligand are discussed. The values of the log KMLA for the systems nicotinic/isonicotinic-amino acids have been ascribed to their differences in the position of the carboxylic group to the pyridine ring, steric hindrance between the ions, size of the chelating agent and electron density of the ring. (author)
[en] The alanine-electron spin resonance (EPR) readout system is well known as a reference and transfer dosimetry system for the evaluation of high doses in radiation processing. The high cost of an EPR/alanine dosimetry system is a serious handicap for large-scale routine application in irradiation facilities. In this study, the use of a complex produced by dissolving irradiated L-alanine in 1,4-phenyl diammonium dichloride solution was investigated for dosimetry purposes. This complex--having a purple colour--has an increasing absorbance with increasing dose in the range of 1-20 kGy. The applicability of spectrophotometric evaluation was studied by measuring the absorbance intensity of this complex at 360 and 505 nm, respectively. Fluorimetric evaluation was also investigated by measuring the emission of the complex at 435 nm as a function of dose. The present method is easy for routine application. The effect of the dye concentration as well as the suitable amount of irradiated alanine has been studied. With respect to routine application, the stability of the product complex after its formation was also investigated