A biuret-derived, MS-cleavable cross-linking reagent for protein structural analysis: A proof-of-principle study.

Chemical cross-linking combined with mass spectrometry (XL-MS) and computational modeling has evolved as an alternative method to derive protein 3D structures and to map protein interaction networks. Special focus has been laid recently on the development and application of cross-linkers that are cleavable by collisional activation as they yield distinct signatures in tandem mass spectra. Building on our experiences with cross-linkers containing an MS-labile urea group, we now present the biuret-based, CID-MS/MS-cleavable cross-linker imidodicarbonyl diimidazole (IDDI) and demonstrate its applicability for protein cross-linking studies based on the four model peptides angiotensin II, MRFA, substance P, and thymopentin.

In silico and in vitro comparative activity of novel experimental derivatives against Leishmania major and Leishmania infantum promastigotes.

This in silico and in vitro comparative study was designed to evaluate the effectiveness of some biurets (K1 to K8) and glucantime against Leishmania major and Leishmania infantum promastigotes. Overall, eight experimental ligands and glucantime were docked using AutoDock 4.3 program into the active sites of Leishmania major and Leishmania infantum pteridine reductase 1, which were modeled using homology modeling programs. The colorimetric MTT assay was used to find L. major and L. infantum promastigotes viability at different concentrations of biuret derivatives in a concentration and time-dependent manner and the obtained results were expressed as 50% and 90% of inhibitory concentration (IC50 and IC90). In silico method showed that out of eight experimental ligands, four compounds were more active on pteridine reductase 1. K3 was the most active against L. major promastigotes with an IC50 of 6.8 µM and an IC90 of 40.2 µM, whereas for L. infantum promastigotes was K8 with IC50 of 7.8 µM. The phenylethyl derivative (K7) showed less toxicity (IC50s>60 µM) in both Leishmania strains. Glucantime displayed less growth inhibition in concentration of about 20 µM. In silico and especially docking results in a recent study were in accordance with the in vitro activity of these compounds in presented study and compound K3, K2 and K8 showed reasonable levels of selectivity for the Leishmania pteridine reductase 1.

One pot glucose detection by [Fe(III)(biuret-amide)] immobilized on mesoporous silica nanoparticles: an efficient HRP mimic.

An [Fe(III)(biuret-amide)] complex has been immobilized onto mesoporous silica nanoparticles via Cu(I) catalyzed azide-alkyne click chemistry. This hybrid material functions as an efficient peroxidase mimic and was successfully used for the quantitative determination of hydrogen peroxide and glucose via a one-pot colorimetric assay.

Synthesis of new glycosyl biuret and urea derivatives as potential glycoenzyme inhibitors.

O-peracetylated 1-(beta-D-glucopyranosyl)-5-phenylbiuret was prepared in the reaction of O-peracetylated beta-D-glucopyranosylisocyanate and phenylurea. The reaction of O-peracetylated N-beta-D-glucopyranosylurea with phenylisocyanate furnished the corresponding 1-(beta-D-glucopyranosyl)-3,5-diphenyl- as well as 3-(beta-D-glucopyranosyl)-1,5-diphenyl biurets besides 1-(beta-D-glucopyranosyl)-3-phenylurea. O-Peracetylated 1-(beta-D-glucopyranosyl)-5-(beta-D-glycopyranosyl)biurets were obtained in one-pot reactions of O-peracetylated beta-D-glucopyranosylamine with OCNCOCl followed by a second glycopyranosylamine of beta-D-gluco, beta-D-galacto and beta-D-xylo configurations. O-Acyl protected 1-(beta-D-glucopyranosyl)-3-(beta-D-glycopyranosylcarbonyl)ureas were obtained from the reaction of beta-D-glucopyranosylisocyanate with C-(glycopyranosyl)formamides of beta-D-gluco and beta-D-galacto configurations. The O-acyl protecting groups were removed under acid- or base-catalyzed transesterification conditions, except for the N-acylurea derivatives where the cleavage of the N-acyl groups was faster than deprotection. Some of the new compounds exhibited moderate inhibition against rabbit muscle glycogen phosphorylase b and human salivary alpha-amylase.

Vibrational circular dichroism spectroscopy of a spin-triplet bis-(biuretato) cobaltate(III) coordination compound with low-lying electronic transitions.

Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy was applied in the analysis of vibrational and low lying electronic transitions of a triplet ground state cobalt(III) coordination compound. The spectroscopic measurements were performed on the tetrabutylammonium salt of (6S,7S)-1,3,5,8,10,12-hexaaza-2,4,9,11-tetraoxo-6,7-diphenyl-dodecanato(4-)cobaltate(III) in DMSO solution and in potassium bromide pellets. The chiral anion exhibits an unusual geometry for cobalt(III), being four-coordinate, planar, and paramagnetic with an intermediate spin state. The spectroscopic results were compared to measurements performed on the free ligand and to theoretical calculations using density functional theory (B3LYP/TZVP). The results of the VCD analysis of the coordination compound identified an electronic, dipole-forbidden, magnetic dipole-allowed low-lying d-d transition located in the mid infrared, as well as several amide stretch transitions located in the fingerprint region (1800-1100 cm(-1)), in both the liquid and solid phase. VCD signals were found to be 5-10 times higher than expected, indicating enhancement of the vibrational CD signals, caused by coupling of the vibrational transitions with the close-lying electronic transition.

Synthesis and biological activity of isodithiobiurets, dithiobiurets, and dithiazoles.

A series of isodithiobiurets, dithiobiurets, and dithiazoles was synthesized and tested for biological activity. Generally, the compounds potentiated the hypnosis induced by pentobarbitone (50 mg/kg ip) in albino mice and exhibited antifungal and insecticidal activity against Fusarium oxysporum and Periplanata americana, respectively. Some compounds showed anticonvulsant and analgesic activity in albino rats.

[Reproduction study of 1,1,3-trimethyl-5-phenylbiuret (ST-281): teratological study in rabbits by oral administration].

Teratogenicity of 1,1,3-trimethyl-5-phenylbiuret (ST-281), a new anti-rheumatic agent, was evaluated in rabbits. ST-281 at doses of 0, 50, 100, 200 and 400 mg/kg/day were administered orally to pregnant NZW rabbits from day 6 to day 18 of pregnancy. Body weight and food consumption at the administration and the subsequent periods were significantly decreased in 400 mg/kg/day group, and 5 dams (41.7%) affected severely were dead. No remarkable changes were investigated in findings at near-term caesarean section in any dosed group including 400 mg/kg/day. In visceral and skeletal examinations, no significant increase in incidence of abnormal fetuses were observed. This report suggests that ST-281 has no embryotoxicity or teratogenicity in rabbits.

Identification of N1-glycolylbiuret in the gamma radiolysis of aerated aqueous solution of cytosine. Influence of the pH.

N1 glycolylbiuret has been identified as a radiation product of cytosine in aerated aqueous solution at pH 4.5. When varying the pH of the solution before irradiation from acidic values towards neutral ones, G value of N1 glycolylbiuret reached a maximum at pH 4.5.

[Penicillin formation by biochemical mutants of Penicillium chrysogenum and their spontaneous revertants]. / Obazovanie penitsillina biokhimicheskimi mutantami Penicillium chrysogenum i ikh spontannymi revertantami.

The capacity for the antibiotic production in the auxotrophs of Penicillium chrysogenum with various deficiency and their revertants was studied. It was found that the capacity for penicillin synthesis was impaired to various degrees in the majority of the auxotrophs. Variants with the penicillin production levels by 13--20 per cent higher than those in the initial prototrophic strain were isolated for the first time in selection of the eukaryotes with the method of obtaining highly active revertants from auxotrophs according to the scheme "prototroph-auxotroph-prototroph".

[Ratio of the mutation spectrum to the physiological state of the Penicillium chrysogenum cell. Auxotrophic mutations induced by N-nitroso-N-methylbiuret in exposure at different stages of DNA replication]. / Zavisimost' spektra mutatsii ot fiziologicheskogo sostoianiia kletki Penicillium chrysogenum. Auksotrofnye mutatsii, indutsirovannye N-nitrozo-N-metilbiuretom pri vozdeistvii na raznye stadii replikatsii DNK.

The effect of UV light on activated conidia of Penicillium chrysogenum, strain 39 was studied. It was found that the spectrum of the auxotrophic mutations induced by UV light during replication of DNA changed with the dose of the mutagen and was specific to every dose. The schemes of predominating mutation induction during DNA replication under the effect of 2 doses of UV light were developed.

[Exclusion of propyl alcohol from the medium for culturing the erythromycin producer]. / Iskliuchenie propilovogo spirta iz sredy dlia kul'tivirovaniia produtsenta éritromitsina.

Propyl alcohol is a precursor of erythromycin. It is one of the components of the medium for production of the antibiotic. Still, this raw material has an unfavorable effect on employees and is fire hazardous. The results of the development of the erythromycin-producing organism are presented. A strain requiring no propyl alcohol as a precursor in the medium and producing the same amounts of the antibiotic was obtained by means of step-wise selection with the use of a mutagen.

[Variability of a Cephalosporium acremonium culture for 2 quantitative traits: antibiotic formation and proteolytic activity]. / Izmenchivost' kul'tury Cephalosporium acremonium po dvum kolichestvennym priznakam--antibiotikoobrazovaniiu i proteoliticheskoi aktivnosti.

Exposure of Cephalosporium acremonium, strain 1435, to N-nitrozo-N-methylbiuret resulted in a changed variation coefficient with respect to two quantitative features--the antibiotic production and proteolytic activity. Correlation between the variation coefficient and mutagen exposure time was different for every feature. Positive correlation was found in variation with respect to the antibiotic production and proteolytic activity in populations of various Cephalosporium acremonium strains chosen with regard to one or two of the above features. The level and form of the correlation in variation of the above features in populations changed during selection. Selection according to the two quantitative features resulted in an increased correlation coefficient.

[Selection of Trichoderma viride, a producer of cellulase]. / Selektsiia Trichoderma viride--produtsenta tselliulazy.

A mutant strain of Trichoderma viride producing cellulase has been obtained as a result of three-stage selection using chemical and physical factors. New variants with modified characteristics appeared after the action of nitroso compounds on a suspension of conidia at the first stage of selection and the action of temperature at the second stage. The new characteristics were intensified and became stable at the third stage of selection. The experimental mutagenesis yielded an active an active mutant of Trichoderma viride 44 which synthesized cellulase (up to 22 units/ml) four times better than the parent culture Trichoderma viride F-57.

[Biosynthesis of the antibiotic, grizin, by prototrophic revertants of Streptomyces griseus biochemical mutants]. / Biosintez antibiotika grizina prototrofnymi revertantami biokhimicheskikh mutantov Streptomyces griseus.

Spontaneous and nitrosomethylbiuret-induced prototrophic revertants of various biochemical mutants of Str. griseus producing grisin, a streptothricin antibiotic, were isolated. The antibiotic production level of the revertants was studied. It was found that most of the prototrophic revertants synthesized much higher amounts of grisin than the initial biochemical mutants. It was also shown that a number of the prototrophic revertants of the methionine- and arginine-dependent mutants synthesized 20-23% higher amounts of grisin as compared to the control.

[Lethal and mutagenic action of N-nitroso-N-methylbiuret on the producers of levorin, amphotericin and mycoheptin]. / Letal'noe i mutagennoe deistvie N-nitrozo-N-metilbiureta na produtsenty levorina, amfoteritsina i mikogeptina.

The lethal and mutagenic effect of N-nitrozo-N-methylbiuret (NMB) on the organisms producing levorin, amphotericin B and mycoheptin was studied. The mutagen effect depended on the dose, culture and physiological state of the spores. NMB had a low mutagenic effect on the levorin-producing organism characterized by high activity and genetic homogenicity with respect to the colony morphology and antibiotic production. As for the organisms producing amphotericin B and mycoheptin characterized by high genetic heterogenicity, significant variation of all the features studied was observed on their exposure to the mutagen. Inspite of diverse reaction of the organisms producing levorin, amphotericin B and mycoheptin to the effect of NMB mutants with increased antibiotic production were obtained from the three cultures. The lethal and mutagenic effect of NMB on the mycoheptin-producing organism depended on the process of the spore DNA replication. The spores during the DNA replication period were least sensitive to the lethal effect of the mutagen and most mutable with the respect to the colony morphology. For selection of highly active and stable strains exposure to NMB of the spores of the mycoheptin-producing organism during replication of DNA proved to be more effective than that of the spores during the lag-phase.

[Actinomyces streptomycini mutants blocked in the biosynthesis of the streptobiosamine portion of the streptomycin molecule]. / Mutanty Actinomyces streptomycini, blokirovannye po biosintezu streptobiozaminovoi chasti molekuly streptomitsina.

Four low active mutants of Act. streptomycini were obtained under the effect of nitrozo-methylbiuret. The mutants increased their antibiotic production level, when streptobiosamine was present in the formentation medium. It was shown that in 3 out of the 4 mutants the highest antibiotic yield was in the medium containing streptobiosamine in an amount of 1 mg/ml and in 1 strain the highest yield was in the medium with 0.5 mg/ml of streptobiosamine. When the mutants were grown in a medium containing N-methyl-L-glucosamine no increase in streptomycin production was registered.

[Dependence of the mutagenic effect of N-nitroso-N-methylbiuret on the pH index]. / Zavisimost' mutagennogo éffekta N-nitrozo-N-metilbiureta ot pokazatelia pH

The mutagenic effect of nitrosocompounds is known to be dependent on pH. The effect of N-nitrozo-N-methylbiuret on the conidia of Penicillium chrysogenum was studied within the ranges of pH from 5.0 to 7.0, the role of the buffer and distilled water being also considered. It was found that survival, morphological variation and induction of biochemical mutants depended on the value of pH. The optimal conditions for the culture treatment at the exposures tested were provided at pH 6.0 with the use of a phosphate buffer mixture as a substrate.

[Variability in Act. circulatus var. monomycini induced by N-5-nitroso-N-methylbiuret]. / Izmenchivost' Act. circulatus var. monomycini, indutsirovannaia N-5-nitrozo-N-metilbiuretom.

The effect of N-5-nitrozo-N-methylbiuret (NMB) on various features of Act. circulatus var. monomycini, an organism producing monomycin was studied. It was found that the lethal effect of NMB depended on the exposure time, prolongation of which resulted in increased numbers of the plus variants, morphological and auxotrophic mutations and reverses into the populations of the monomycin-producing organism. An increase in the temperature of the treatment had an effect on the frequency of morphological and auxotrophic mutations inducing an increase in the number of the first and some decrease in the number of the second. The fact of specificity in formation of the vitamin B6-deficient auxotrophic mutants of the same type was of special interest. This was probably associated with genetic peculiar properties of the culture. It was supposed that the genes controlling biosynthesis of vitamin B6 were localized on the actinomycete plasmids, elimination of which under the effect of NMB resulted in blocking of vitamin B6 synthesis which in its turn impaired the reactions of transaminations participating in formation of monomycin.

[Isolation and characteristics of UV-resistant revertants of recA-strains of Escherichia coli K-12]. / Vydelenie i kharakteristika UF-rezistentnykh revertantov recA-shtammov Escherichia coli K-12

The paper presents the results of a study of UV-resistant revertants of some recA strains induced by different mutagens. It is shown that some of produced revertants differ from original recA strains in some properties. It is established that all UV-resistant revertant fall into three phenotypic groups on their recombination proficiency in crosses with different donor strains (Hfr C, Hfr 3.0SO, F' W1655) and in their sensitivity to UV and gamma-rays. It is concluded that all UVr revertants are rec A+ and carried mutations either in the same recA gene (true reversion or intragenic suppression) or in genes closely linked with recA.