A sensitive radiochemical assay for Coenzyme A

Summary A simple and sensitive assay for Coenzyme A (CoA) is described. The method is based on coupling the enzymatic reactions of acetyl-CoA synthetase and acetyl-CoA carboxylase. CoA is converted into acetyl-CoA with acetyl-CoA synthetase in the presence of excess ATP and acetate. Acetyl-CoA is subsequently converted into malonyl-CoA with acetyl-CoA carboxylase in the presence of excess ATP and KH¹⁴CO₃. The formation of labelled acid-stable material (i.e. malonyl-CoA) is determined. Under conditions of the assay CoA is quantitatively converted into malonyl-CoA. This procedure permits the detection of as little as 15 pmoles of CoA in biological samples. Elimination of acetyl-CoA synthetase from the reaction mixture allows for the determination of acetyl-CoA.

---

Empfindlicher radiochemischer Assay für Coenzym A

Zusammenfassung Ein einfacher und empfindlicher Assay für Coenzym A (CoA) wird beschrieben, der auf einer Kopplung der enzymatischen Reaktionen von Acetyl-CoA-synthetase und Acetyl-CoA-carboxylase beruht. CoA wird mit Hilfe von Acetyl-CoA-synthetase in Gegenwart von überschüssigem ATP und Acetat zu Acetyl-CoA umgesetzt. Dieses wird anschließend mit Acetyl-CoA-carboxylase in Gegenwart von überschüssigem ATP und KH¹⁴CO₃ zu Malonyl-CoA umgewandelt. Die Bildung von markierter säurestabiler Substanz (d.h. Malonyl-CoA) wird bestimmt. Unter den Versuchsbedingungen ist die Umsetzung von CoA zu Malonyl-CoA quantitativ. Noch 15 pMol CoA können in biologischem Material erfaßt werden. Durch Entfernung von Acetyl-CoA-synthetase aus dem Reaktionsgemisch kann auch Acetyl-CoA bestimmt werden.

     

A photoprecursor for difluorocarbene

4,4-Difluoropyrazolidine-3,5-dione was synthesized as a precursor for the corresponding pyrazolinedione, envisioned as a photochemical source of difluorocarbene. However, this azo compound proved to be far too unstable. In contrast, 10,10-difluorobicyclo[4.3.1]deca-1,3,5-triene, readily synthesized from indane, was found to be a practical source of difluorocarbene for photochemical as well as thermal cyclopropanation reactions.     

A test for cobalt

Summary Cobalt may be detected by means of dimethylglyoxime and iodide in slightly acid solution. Yellow colorations are obtained in test tube and in spot tests. Yellow to red crystals are obtained on the microscope slide. The data on sensitivity are compiled in Table 1.

---

Zusammenfassung Kobalt kann in schwach saurer Lösung mit Dimethylglyoxim und Jodid nachgewiesen werden. Gelbfärbungen werden dabei in Reagensglasversuchen und in Tüpfelproben erhalten. Unter dem Mikroskop können charakteristische gelbe bis rote Kristalle erkannt werden. Alle Angaben über die Empfindlichkeit der Probe sind in Tabelle 1 zusammengefaßt.

---

Résumé Le cobalt peut être recherché en solution faiblement acide avec la diméthylglyoxime et un iodure. On a obtenu des colorations jaunes dans des tubes à essais et des expériences à la touche. Sous le microscope, on peut former des cristaux caractéristiques, rouges et jaunes. Toutes les données sur la sensibilité de l'essai sont consignées dans le tableau 1.

---

---

With 4 figures.     

A case for sharing

Unlike in other branches of science and technology, computer programs and algorithms are generally not fully disclosed. This leads to duplication of effort, and prevents building new knowledge rapidly on existing knowledge. To remedy this, effective patents on computer programs and algorithms should be granted. The community of authors and inventors, along with expert advice from patent attorneys, have to arrive at effective and equitable definitions of obviousness and novelty, so that the boundaries of protection on one side, and free progress on the other, can be defined. The same reasons exist for patenting and disclosing computer software knowledge as for chemistry, electrical and mechanical inventions. Patenting has protected inventors and assured progress for many decades successfully in these fields.     

A method for the preparation of corchoroside A

Chemistry of Natural Compounds -     

A Nanoemulsion with A Porphyrin Shell for Cancer Theranostics

A nanoemulsion with a porphyrin shell (NewPS) was created by the self‐assembly of porphyrin salt around an oil core. The NewPS system has excellent colloidal stability, is amenable to different porphyrin salts and oils, and is capable of co‐loading with chemotherapeutics. The porphyrin salt shell enables porphyrin‐dependent optical tunability. The NewPS consisting of pyropheophorbide a mono‐salt has a porphyrin shell of ordered J‐aggregates, which produced a narrow, red‐shifted Q‐band with increased absorbance. Upon nanostructure dissociation, the fluorescence and photodynamic reactivity of the porphyrin monomers are restored. The spectrally distinct photoacoustic imaging (at 715 nm by intact NewPS) and fluorescence increase (at 671 nm by disrupted NewPS) allow the monitoring of NewPS accumulation and disruption in mice bearing KB tumors to guide effective photodynamic therapy. Substituting the oil core with Lipiodol affords additional CT contrast, whereas loading paclitaxel into NewPS facilitates drug delivery.     

L－天冬氨酸微生物电极的研制

本文以大肠杆菌为天冬氨酸脱氨反应的酶源,采用氨气敏电极为基础电极研制成L-天冬氨酸微生物电极。对细菌培养条件、固定方法及电极工作条件等进行了研究,测定L-天冬氨酸E～1gC曲线斜率为55mV,线性范围为6.0×10^-4～8.0×10^-3mol/L,寿命可达10天。     

A fluorimetric assay for cortisol

A simple, rapid and sensitive fluorimetric assay for the quantitative determination of cortisol is reported. The assay is based on the formation of a fluorescent dye when cortisol is incubated with a mixture of sulfuric acid and acetic acid. The fluorescence spectrum recorded for the resulting dye shows a maximum extinction at 475 nm and a maximum emission at 525 nm. The solvent 2-methyl-4-pentanone was used for extraction and was found to act as a fluorescence amplifier. A limit of detection of 2.7 μM was achieved, making it possible to forego solvent evaporation. The assay suffers minor interference from 11-deoxycortisol which exhibits low fluorescence at λ _ex: 460 nm; λ _em: 505 nm. Typical standard deviations were below 4%. We validated the assay using a biotransformation with recombinant Schizosaccharomyces pombe which regioselectively hydroxylates 11-deoxycortisol to cortisol. The method described herein is suitable for preliminary screening of microorganisms capable of steroid hydroxylation.     

A Sensitive Analysis for Nitrosamines

Abstract

A number of nitrosamines have been reduced to hydrazines and condensed with 9-anthraldehyde and 9-phenanthraldehyde to give highly fluorescent hydrazones which can be separated by thin layer chromatography and identified using R_f, ultroviolet and mass spectra.     

A Chemical Probe for Dehydrobutyrine

Bacterial phosphothreonine lyases, or phospholyases, catalyze a unique post‐translational modification that introduces dehydrobutyrine (Dhb) or dehydroalanine (Dha) in place of phosphothreonine or phosphoserine residues, respectively. We report the use of a phospha‐Michael reaction to label proteins and peptides modified with Dha or Dhb. We demonstrate that a nucleophilic phosphine probe is able to modify Dhb‐containing proteins and peptides that were recalcitrant to reaction with thiol or amine nucleophiles under mild aqueous conditions. Furthermore, we used this reaction to detect multiple Dhb‐modified proteins in mammalian cell lysates, including histone H3, a previously unknown target of phospholyases. This method should prove useful for identifying new phospholyase targets, profiling the biomarkers of bacterial infection, and developing enzyme‐mediated strategies for bioorthogonal labeling in living cells.     

A model for free-radical reactions

Using an EHT type Hamiltonian the Heitler-London-VB treatment of the three-centre three-electron problem is simplified such that the interesting features of the potential hypersurfaces of arbitrary three-centre three-electron systems can be obtained simply from the knowledge of atomic orbital energies and overlap integrals. The method is applied to the hypersurfaces of the H₃ system and extensions of the discussion of general radical reactions are indicated.     

A microwave-assisted microassay for lipases

A quick and efficient two-step assay for monitoring and screening lipase activity that uses a microtitre plate is described.     

苦杏仁甙化学发光生物传感器

将具有分子识别功能的β－葡萄糖甙酶和能进行换能反应的Ｌｕｍｉｎｏｌ分别固定在壳质胺和大孔阴离子交换剂的柱中,组成流动注射系统。苦杏仁甙在β－葡萄糖甙酶催化下分解生成的ＣＮ＾－（分子识别反应）与溶解氧反应生成超氧阴离子自由基,继而同Ｌｕｎｉｎｌ反应产生化学发光（换能反应）。这一新型生物传感器的化学发光强度与苦杏杜甙量在１～２００ｕｇ之间呈良好线性关系,检出限为０．３ｕｇ,相对标准偏差为３．１％,并具     

氟丙嘧草酯的合成新工艺

以2-氯-5-硝基苯甲酸甲酯为原料,经还原、缩合得2-氯-5-(乙氧羰基)氨基苯甲酸甲酯(3);3与3-氨基-4,4,4-三氟巴豆酸乙酯进行环合得脲嘧啶环中间体(4);4经甲基化、水解、酰化和缩合反应合成了氟丙嘧草酯,总收率55.2%,纯度99.1%。中间体和产物结构经1H NMR和EI-MS确证。