IMPRINTING EFFECTS OF THREE AMINO ACIDS (ALANINE,LYSINE AND GLYCINE) AND THEIR OLIGOPEPTIDES INTETRAHYMENA PYRIFORMIS. DATA FROM THE HORMONE AND HORMONE RECEPTOR EVOLUTION

Hormonal imprinting takes place at the first encounter of the hormone and receptor, and results in a changed binding capacity and reaction of the cell and its progeny generations. The imprinting effect of three amino acids and their oligopeptides is studied using fluorescent-labelled peptides. Glycine and lysine could provoke positive imprinting (increased binding in the progeny generations) for their own peptides, but alanine could not. Mostly positive imprinting was provoked by glycine and lysine peptides for their own peptides of different chain length. The optimal chain length provoking self-imprinting was four for glycine, two for lysine and three for alanine. Except in this case, alanine was neutral or provoked mostly negative imprinting. After reaching the optimal chain length, there is a decline in binding. Evolutionary conclusions are discussed.     

Biotransformation of diphenyl ether by the yeastTrichosporon beigelii SBUG 752

Trichosporon beigelii SBUG 752 was able to transform diphenyl ether. By TLC, HPLC, GC, GC-MS, NMR- and UV-spectroscopy, several oxidation products were identified. The primary attack was initiated by a monooxygenation step, resulting in the formation of 4-hydroxydiphenyl ether, 2-hydroxydiphenyl ether and 3-hydroxydiphenyl ether (48:47:5). Further oxidation led to 3,4-dihydroxydiphenyl ether. As a characteristic product resulting from the cleavage of an aromatic ring, the lactone of 2-hydroxy-4-phenoxymuconic acid was identified. The possible mechanism of ring cleavage to yield this metabolite is discussed.     

Chemical behaviour of cytidine 5'-monophospho-N-acetyl-beta-D-neuraminic acid under neutral and alkaline conditions

The chemical behaviour of CMP-N-acetylneuraminic acid under neutral and different alkaline conditions has been investigated. The products formed were isolated by ion-exchange chromatography and gel filtration and analysed by colorimetric methods, thin-layer chromatography, combined gas-liquid chromatography/mass spectrometry and/or 360-MHz 1H-NMR spectroscopy. A maximum stability of CMP-N-acetylneuraminic acid was observed at pH8-11. In the tested pH range of 6-13, CMP and N-acetylneuraminic acid were formed in variable amounts as decomposition products. 2-Deoxy-2,3-dehydro-N-acetylneuraminic acid was produced at pH greater than 7; the amount of this substance increased with increasing pH. In anhydrous triethylamine its yield was 50%. A new neuraminic acid derivative, N-acetyl-beta-D-neuraminic acid 2-phosphate, could be isolated from the mixture of alkaline decomposition products of CMP-N-acetylneuraminic acid. The yield of this compound was maximum 22% in anhydrous triethylamine. Because 2-deoxy-2,3-dehydro-N-acetylneuraminic acid was formed under simulated physiological conditions, it is assumed that this compound, which occurs in tissues and fluids of man and animals, is derived from CMP-N-acetylneuraminic acid non-enzymically also under conditions in vivo.     

The distribution of keratin type intermediate filaments in human breast cancer. An immunohistological study

Antibodies to different intermediate filament proteins can be used to distinguish cells of epithelial, mesenchymal, muscle, glial and neuronal origin. Antibodies to prekeratin which characterize cells of epithelial origin, and antibodies to vimentin which recognize cells of mesenchymal origin have been used to study twenty cases of breast carcinoma (sixteen infiltrating ductal carcinomas and four infiltrating intraductal carcinomas), two cases of cystic breast disease, two fibroadenomas and one case of benign cystosarcoma phylloides. The prekeratin and vimentin were detected using specific antibodies to these proteins by immunofluorescence microscopy using alcohol fixed paraffin-embedded tissues. In eighteen out of the twenty carcinomas the tumor cells were strongly and specifically stained by antibodies to prekeratin. DIfferent tumors gave different patterns of prekeratin staining. In contrast, when the same specimens were tested with the vimentin antibody, the tumor cells were unstained, and instead only the usual strong staining to fibroblasts and blood vessels in the stroma was observed. In cystic breast disease, fibroadenomas, and benign cystosarcoma phylloides, cells of epithelial origin were strongly stained by the prekeratin but not by the vimentin antibody.     

Kinetics of Formate Metabolism in Methanobacterium formicicum and Methanospirillum hungatei

The kinetics of formate metabolism in Methanobacterium formicicum and Methanospirillum hungatei were studied with log-phase formate-grown cultures. The progress of formate degradation was followed by the formyltetrahydrofolate synthetase assay for formate and fitted to the integrated form of the Michaelis-Menten equation. The K_m and V_max values for Methanobacterium formicicum were 0.58 mM formate and 0.037 mol of formate h⁻¹ g⁻¹ (dry weight), respectively. The lowest concentration of formate metabolized by Methanobacterium formicicum was 26 μM. The K_m and V_max values for Methanospirillum hungatei were 0.22 mM and 0.044 mol of formate h⁻¹ g⁻¹ (dry weight), respectively. The lowest concentration of formate metabolized by Methanospirillum hungatei was 15 μM. The apparent K_m for formate by formate dehydrogenase in cell-free extracts of Methanospirillum hungatei was 0.11 mM. The K_m for H₂ uptake by cultures of Methanobacterium formicicum was 6 μM dissolved H₂. Formate and H₂ were equivalent electron donors for methanogenesis when both substrates were above saturation; however, H₂ uptake was severely depressed when formate was above saturation and the dissolved H₂ was below 6 μM. Formate-grown cultures of Methanobacterium formicicum that were substrate limited for 57 h showed an immediate increase in growth and methanogenesis when formate was added to above saturation.     

Isolation and characterization of acylneuraminate cytidylyltransferase from frog liver

Frog liver (Rana esculenta) is a rich source of acylneuraminate cytidylyltransferase. The soluble enzyme was purified 250-fold almost to purity with 25% yield and a specific activity of 9 mkat/kg protein (0.54 U/mg protein) using DEAE Sephadex and Sepharose 6B chromatography, followed by preparative polyacrylamide gel electrophoresis. The molecular weight of the cytidylyltransferase was determined to be 163 000 with the aid of Sepharose 6B chromatography and gel electrophoresis, with or without dodecyl sulphate or urea. No subunits were found. The isoelectric point of the enzyme is at pH 6. Optimum reaction rate was observed at pH 9, 37 degrees C, 50mM Mg2 or Ca2 and ImM mercaptoethanol. The Km values for N-acetylneuraminic acid, N-glycoloylneuraminic acid and CTP are 1.6mM, 2.3 mM and 0.6mM, respectively. O-Acetylated sialic acids are inactive with the cytidylyltransferase from frog liver. Enzyme activity can be inhibited by SH reagents and CMP (Ki = 0.5mM).     

The preparation of CMP-sialic acids by using CMP-acylneuraminate synthase from frog liver immobilized on sepharose 4B.

A preparation of frog liver CMP-acylneuraminate synthase (2-10-fold enriched over the homogenate) obtained from DEAE-Sephadex A-50 chromatography of a 105,000g liver supernatant was bound to Sepharose 4B by the CNBr method. The enzyme retained 80-100% activity on binding and showed similar properties to the purified soluble enzyme from the same source with respect to Km, pH optimum and inhibition. The bound enzyme was stable to temperatures above 40 degrees C, in contrast with the soluble enzyme, and could be stored for 4 months at 2 degrees C with loss of 20% activity. The bound enzyme was used preparatively for the synthesis of radioactive and non-radioactive CMP-N-acetylneuraminic acid and CMP-N-glycolloylneuraminic acid. With suitable substrate concentrations and ratios, yields of 80% and over can be achieved.     

Unifying Charge Generation,Recombination, and Extraction in Low‐Offset Non‐Fullerene Acceptor Organic Solar Cells

Even though significant breakthroughs with over 18% power conversion efficiencies (PCEs) in polymer:non‐fullerene acceptor (NFA) bulk heterojunction organic solar cells (OSCs) have been achieved, not many studies have focused on acquiring a comprehensive understanding of the underlying mechanisms governing these systems. This is because it can be challenging to delineate device photophysics in polymer:NFA blends comprehensively, and even more complicated to trace the origins of the differences in device photophysics to the subtle differences in energetics and morphology. Here, a systematic study of a series of polymer:NFA blends is conducted to unify and correlate the cumulative effects of i) voltage losses, ii) charge generation efficiencies, iii) non‐geminate recombination and extraction dynamics, and iv) nuanced morphological differences with device performances. Most importantly, a deconvolution of the major loss processes in polymer:NFA blends and their connections to the complex BHJ morphology and energetics are established. An extension to advanced morphological techniques, such as solid‐state NMR (for atomic level insights on the local ordering and donor:acceptor π? π interactions) and resonant soft X‐ray scattering (for donor and acceptor interfacial area and domain spacings), provide detailed insights on how efficient charge generation, transport, and extraction processes can outweigh increased voltage losses to yield high PCEs.