Abstract Die UV‐Photolyse der endo‐ und exo‐Homoallylalkohole (I) liefert Gemische der jeweils isomeren Aldehyde (II) und (III), die bei kurzen Reaktionszeiten die einzigen Produkte sind.
SNP genotyping typically incorporates a review step to ensure that the genotype calls for a particular SNP are correct. For high-throughput genotyping, such as that provided by the GenomeLab SNPstream instrument from Beckman Coulter, Inc., the manual review used for low-volume genotyping becomes a major bottleneck. The work reported here describes the application of a neural network to automate the review of results.We describe an approach to reviewing the quality of primer extension 2-color fluorescent reactions by clustering optical signals obtained from multiple samples and a single reaction set-up. The method evaluates the quality of the signal clusters from the genotyping results. We developed 64 scores to measure the geometry and position of the signal clusters. The expected signal distribution was represented by a distribution of a 64-component parametric vector obtained by training the two-layer neural network onto a set of 10,968 manually reviewed 2D plots containing the signal clusters.The neural network approach described in this paper may be used with results from the GenomeLab SNPstream instrument for high-throughput SNP genotyping. The overall correlation with manual revision was 0.844. The approach can be applied to a quality review of results from other high-throughput fluorescent-based biochemical assays in a high-throughput mode.
Abstract Since steroids are only slightly soluble in the aqueous solutions in which enzymatic reactions take place, it is difficult to obtain high effective concentrations per unit reactor volume when enzymes are used to catalyze steroid reactions. In order to obtain high effective concentrations in the present work, we have used small particles of a hydrophobic polymer, poly (dimethyl siloxane), as a reservoir for the steroid substrate and product. The activity of a bacterial hydroxysteroid dehydrogenase in a buffer solution declines much more slowly in the presence of those polymer particles than in the presence of a comparable amount of butyl acetate or ethyl acetate, the organic solvents used as steroid reservoirs in previous work with steroid transforming enzymes. When another substrate of the hydroxysteroid dehydrogenase is loaded into the polymer particles and the particles are suspended in an aqueous solution containing the enzyme and its cofactor, more product is formed that when a similar solution is emulsified with butyl acetate.
The principal raw material for the production of steroid pharmaceuticals is diosgenin obtained from the Mexican plant Dioscorea. In light of the slow growth of diosgenin production, there is considerable interest in a more intensive use of stigma-sterol and cholesterol as raw materials (Fig. 1). One route from these sterols to the widely used steroid norethindrone involves initial conversion of the sterol to an intermediate called 1,4 androstadiene 3,17 dione (1,4 ADD). A number of bacteria are capable of transforming sterols to 1,4 ADD, synthesizing the necessary enzymes when steroids are present in their growth media (1,2). Mitsubishi Chemical Industries have recently developed a microbiological process to carry out this transformation (3). The possibility also exists of using bacterial extracts containing the appropriate enzymes to catalyze some or all of the steps in the process. Once the sterol side chain is oxidized to a 17 keto group, three enzymes from a strain of Pseudomonas testosteroni catalyze the remaining reactions in the process which are shown in Fig. 2 (4,5,6). Two problems must be solved before these enzymes can be reasonably applied to the conversion. One is that expensive electron acceptors must be recycled, and the other is that the enzymes must be in a form that allows them to be used in a continuous process or to be recovered at the end of each cycle of a batch process.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganic photochemistry with 6.7-eV photons: rigid homoallylic alcohols. An inverse Norrish type II rearrangementJoel Studebaker, R. Srinivasan, Jose A. Ors, and Thomas BaumCite this: J. Am. Chem. Soc. 1980, 102, 22, 6872–6874Publication Date (Print):October 15, 1980Publication History Published online1 May 2002Published inissue 15 October 1980https://pubs.acs.org/doi/10.1021/ja00542a048https://doi.org/10.1021/ja00542a048research-articleACS PublicationsRequest reuse permissionsArticle Views88Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
A flow-through cartridge for indicating acidic and basic conditions during acid regeneration of immunoadsorption columns is described. Based on a pH dye covalently bound to polyacrylamide beads, it offers a direct visual indication of whether the pH of a column is in a range which is safe for use. The device, mounted in the waste line, may be reused several times.
The absorption and fluorescence spectra of several aromatic hydrocarbons complexed with tetrachlorophthalic anhydride (TCPA) dispersed in polymethylmethacrylate (PMMA) have been studied in the 0–25-kbar range. The pressure effect on the charge transfer (CT) absorption intensity and band maxima have been compared with low-temperature measurements. The molar extinction coefficient increases ∼100% at 77°K relative to 298°K and increases 100%—400% at 25 kbar relative to atmospheric pressure. The absorption-band maxima are rather insensitive to temperature, but shift red by ∼1500 cm−1 at 25 kbar. The CT fluorescence shows only ∼500 cm−1 red shift at 30 kbar. The difference can be rationalized in terms of potential-energy curves for the ground and excited states characterizing the molecular complex.
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