ОПРЕДЕЛЕНИЕ СИНТЕТИЧЕСКИХ КРАСИТЕЛЕЙ Е102, Е110, Е124, Е131 В ЙОГУРТЕ МЕТОДОМ ТВЕРДОФАЗНОЙ СПЕКТРОФОТОМЕТРИИ

Tartrazine E102, Yellow "Sunset" E110, Ponso 4R E124 and the Patented Blue E131 food synthetic dyes solid-phase extraction from yoghurts and biokefirs in a transparent polymethylmethacrylate matrix as a solid extractant was studied. The analytical signal was formed due to the accumulation of the dye in the volume of the polymer matrix without violating the transparency, and this corresponded to the wavelength of the maximum absorption of the corresponding dye. The sorption mechanism was based on the protonization of the carbonyl groups of PMM in the acidic media, and, as a result, the optode surface became positively charged. Therefore, the sorption of the R± form of the E131 dye and the azo dye anions occurred by the positively charged PMM surface. The effectiveness of the proposed approach was shown for the identification and determination of the 2 food-grade synthetic dyes content using the visual and spectrophotometric methods. The optimal conditions for the analysis corresponded to pH 3, the duration of dye extraction into the polymer matrix was 20 min, the range of the detected concentrations was 0.2–40.0  mg / kg with the detection limit of 0.05 mg/kg, and an excess of sweeteners and preservatives did not significantly affect the results of the analysis. The results of the determination of the listed dyes were demonstrated in the current work for the case of individual and group presence of dyes in biokefirs and yogurts. The proposed technique is simple in execution and could be carried out using the standard spectrophotometric equipment. The advantage of the developed method for the determination of artificial dyes in comparison with the method of spectrophotometric determination with liquid extraction is a significant increase in the sensitivity of determination due to the accumulation of analyte, the exclusion of turbidity of an aliquot and the absence of dye loss due to its transition into the supernatant, and then into the solid phase of the matrix.Keywords: colorimetric sensor, solid-phase spectrophotometry, polymethylmethacrylate matrix, synthetic food colorant, dairy productDOI: http://dx.doi.org/10.15826/analitika.2020.24.1.002  A.A. Dudkina1, N.V. Saranchina1, T.N. Volgina1, N.A. Gavrilenko2, M.A. Gavrilenko11Tomsk Polytechnic University, 30 Lenin Ave, Tomsk, 634050, Russian Federation2Tomsk State University, 36 Lenin Ave, Tomsk, 634050, Russian FederationИзучена твердофазная экстракция пищевых синтетических красителей тартразин Е102, желтый «солнечный закат» Е110, понсо 4R Е124 и патентованный синий Е131 из йогуртов и биокефиров в прозрачную полиметилметакрилатную матрицу в качестве твердого экстрагента. Аналитический сигнал формируется вследствие накопления красителя в объеме полимерной матрицы без нарушения прозрачности и соответствует длине волны максимума поглощения соответствующего красителя. Механизм сорбции основан на том, что в кислых средах карбонильные группы ПММ способны подвергаться протонизации, за счет этого поверхность оптода становится положительно заряженной. Таким образом, происходит сорбция R± формы красителя Е131 и  анионов азокрасителей положительно заряженной поверхностью ПММ. Показана эффективность предложенного подхода для идентификации и определения содержания двух пищевых синтетических красителей визуальным и спектрофотометрическим методом. Найдены оптимальные условия проведения анализа: рН 3, продолжительность экстракции красителей в полимерную матрицу 20 минут, диапазон определяемых концентраций 0.2–40.0 мг/кг с пределом обнаружения 0.05 мг/кг, избыток подсластителей и консервантов не оказывает существенного влияния на результаты анализа. Приведены результаты определения перечисленных красителей, в том числе при их совместном присутствии в образцах биокефиров и йогуртов. Методика осуществляется на спектрофотометрическом оборудовании, либо простой полуколичественной визуальной оценкой. Преимуществом разработанной методики определения искусственных красителей по сравнению с методом спектрофотометрического определения с жидкостной экстракцией является значительное повышение чувствительности определения вследствие накопления аналита и исключения мутности аликвоты, а также отсутствие потерь красителя вследствие его перехода в надосадочную жидкость и, затем, в твердую фазу матрицы.Ключевые слова: колориметрический сенсор, твердофазная спектрофотометрия, полиметилметакрилатная матрица, синтетический пищевой краситель, молочный продуктDOI: http://dx.doi.org/10.15826/analitika.2020.24.1.00

The higher level of organization of the oxidative phosphorylation system: mitochondrial supercomplexes

The organization of the oxidative phosphorylation (OXPHOS) system within the inner mitochondrial membrane appears to be far more complicated than previously thought. In particular, the individual protein complexes of the OXPHOS system (complexes I to V) were found to specifically interact forming defined supramolecular structures. Blue-native polyacrylamide gel electrophoresis and single particle electron microscopy proved to be especially valuable in studying the so-called “respiratory supercomplexes”? Based on these procedures, increasing evidence was presented supporting a “solid state” organization of the OXPHOS system. Here, we summarize results on the formation, organisation and function of the various types of mitochondrial OXPHOS supercomplexes

Highly Divergent Mitochondrial ATP Synthase Complexes in Tetrahymena thermophila

Tetrahymena ATP synthase, an evolutionarily divergent protein complex, has a very unusual structure and protein composition including a unique Fo subunit a and at least 13 proteins with no orthologs outside of the ciliate lineage

Determination of Е102, Е110, Е124, Е131 synthetic dyes in yogurt using the solid-phase spectrophotometry

Изучена твердофазная экстракция пищевых синтетических красителей тартразин Е102, желтый «солнечный закат» Е110, понсо 4R Е124 и патентованный синий Е131 из йогуртов и биокефиров в прозрачную полиметилметакрилатную матрицу в качестве твердого экстрагента. Аналитический сигнал формируется вследствие накопления красителя в объеме полимерной матрицы без нарушения прозрачности и соответствует длине волны максимума поглощения соответствующего красителя. Механизм сорбции основан на том, что в кислых средах карбонильные группы ПММ способны подвергаться протонизации, за счет этого поверхность оптода становится положительно заряженной. Таким образом, происходит сорбция R± формы красителя Е131 и анионов азокрасителей положительно заряженной поверхностью ПММ. Показана эффективность предложенного подхода для идентификации и определения содержания двух пищевых синтетических красителей визуальным и спектрофотометрическим методом. Найдены оптимальные условия проведения анализа: рН < 3, продолжительность экстракции красителей в полимерную матрицу 20 минут, диапазон определяемых концентраций 0.2–40.0 мг/кг с пределом обнаружения 0.05 мг/кг, избыток подсластителей и консервантов не оказывает существенного влияния на результаты анализа. Приведены результаты определения перечисленных красителей, в том числе при их совместном присутствии в образцах биокефиров и йогуртов. Методика осуществляется на спектрофотометрическом оборудовании, либо простой полуколичественной визуальной оценкой. Преимуществом разработанной методики определения искусственных красителей по сравнению с методом спектрофотометрического определения с жидкостной экстракцией является значительное повышение чувствительности определения вследствие накопления аналита и исключения мутности аликвоты, а также отсутствие потерь красителя вследствие его перехода в надосадочную жидкость и, затем, в твердую фазу матрицы.Tartrazine E102, Yellow "Sunset" E110, Ponso 4R E124 and the Patented Blue E131 food synthetic dyes solid-phase extraction from yoghurts and biokefirs in a transparent polymethylmethacrylate matrix as a solid extractant was studied. The analytical signal was formed due to the accumulation of the dye in the volume of the polymer matrix without violating the transparency, and this corresponded to the wavelength of the maximum absorption of the corresponding dye. The sorption mechanism was based on the protonization of the carbonyl groups of PMM in the acidic media, and, as a result, the optode surface became positively charged. Therefore, the sorption of the R± form of the E131 dye and the azo dye anions occurred by the positively charged PMM surface. The effectiveness of the proposed approach was shown for the identification and determination of the 2 food-grade synthetic dyes content using the visual and spectrophotometric methods. The optimal conditions for the analysis corresponded to pH <3, the duration of dye extraction into the polymer matrix was 20 min, the range of the detected concentrations was 0.2–40.0 mg / kg with the detection limit of 0.05 mg/kg, and an excess of sweeteners and preservatives did not significantly affect the results of the analysis. The results of the determination of the listed dyes were demonstrated in the current work for the case of individual and group presence of dyes in biokefirs and yogurts. The proposed technique is simple in execution and could be carried out using the standard spectrophotometric equipment. The advantage of the developed method for the determination of artificial dyes in comparison with the method of spectrophotometric determination with liquid extraction is a significant increase in the sensitivity of determination due to the accumulation of analyte, the exclusion of turbidity of an aliquot and the absence of dye loss due to its transition into the supernatant, and then into the solid phase of the matrix

Mitochondrial DNA Backgrounds Might Modulate Diabetes Complications Rather than T2DM as a Whole

Mitochondrial dysfunction has been implicated in rare and common forms of type 2 diabetes (T2DM). Additionally, rare mitochondrial DNA (mtDNA) mutations have been shown to be causal for T2DM pathogenesis. So far, many studies have investigated the possibility that mtDNA variation might affect the risk of T2DM, however, when found, haplogroup association has been rarely replicated, even in related populations, possibly due to an inadequate level of haplogroup resolution. Effects of mtDNA variation on diabetes complications have also been proposed. However, additional studies evaluating the mitochondrial role on both T2DM and related complications are badly needed. To test the hypothesis of a mitochondrial genome effect on diabetes and its complications, we genotyped the mtDNAs of 466 T2DM patients and 438 controls from a regional population of central Italy (Marche). Based on the most updated mtDNA phylogeny, all 904 samples were classified into 57 different mitochondrial sub-haplogroups, thus reaching an unprecedented level of resolution. We then evaluated whether the susceptibility of developing T2DM or its complications differed among the identified haplogroups, considering also the potential effects of phenotypical and clinical variables. MtDNA backgrounds, even when based on a refined haplogroup classification, do not appear to play a role in developing T2DM despite a possible protective effect for the common European haplogroup H1, which harbors the G3010A transition in the MTRNR2 gene. In contrast, our data indicate that different mitochondrial haplogroups are significantly associated with an increased risk of specific diabetes complications: H (the most frequent European haplogroup) with retinopathy, H3 with neuropathy, U3 with nephropathy, and V with renal failure

CryoEM reveals how the complement membrane attack complex ruptures lipid bilayers

The membrane attack complex (MAC) is one of the immune system’s first responders. Complement proteins assemble on target membranes to form pores that lyse pathogens and impact tissue homeostasis of self-cells. How MAC disrupts the membrane barrier remains unclear. Here we use electron cryo-microscopy and flicker spectroscopy to show that MAC interacts with lipid bilayers in two distinct ways. Whereas C6 and C7 associate with the outer leaflet and reduce the energy for membrane bending, C8 and C9 traverse the bilayer increasing membrane rigidity. CryoEM reconstructions reveal plasticity of the MAC pore and demonstrate how C5b6 acts as a platform, directing assembly of a giant β-barrel whose structure is supported by a glycan scaffold. Our work provides a structural basis for understanding how β-pore forming proteins breach the membrane and reveals a mechanism for how MAC kills pathogens and regulates cell functions

Interaction of complexes I, III, and IV within the bovine respirasome by single particle cryoelectron tomography

The respirasome is a multisubunit supercomplex of the respiratory chain in mitochondria. Here we report the 3D reconstruction of the bovine heart respirasome, composed of dimeric complex III and single copies of complex I and IV, at about 2.2-nm resolution, determined by cryoelectron tomography and subvolume averaging. Fitting of X-ray structures of single complexes I, III2, and IV with high fidelity allows interpretation of the model at the level of secondary structures and shows how the individual complexes interact within the respirasome. Surprisingly, the distance between cytochrome c binding sites of complexes III2 and IV is about 10 nm. Modeling indicates a loose interaction between the three complexes and provides evidence that lipids are gluing them at the interfaces