Short-Chain Dehydrogenase NcmD Is Responsible for the C-10 Oxidation of Nocamycin F in Nocamycin Biosynthesis

Nocamycins I and II, featured with a tetramic acid scaffold, were isolated from the broth of Saccharothrix syringae NRRL B-16468. The biosynthesis of nocamycin I require an intermediate bearing a hydroxyl group at the C-10 position. A short chain dehydrogenase/reductase NcmD was proposed to catalyze the conversion of the hydroxyl group to ketone at the C-10 position. By using the λ-RED recombination technology, we generated the NcmD deletion mutant strain S. syringae MoS-1005, which produced a new intermediate nocamycin F with a hydroxyl group at C-10 position. We then overexpressed NcmD in Escherichia coli BL21 (DE3), purified the His6-tagged protein NcmD to homogeneity and conducted in vitro enzymatic assays. NcmD showed preference to the cofactor NAD+, and it effectively catalyzed the conversion from nocamyin F to nocamycin G, harboring a ketone group at C-10 position. However, NcmD showed no catalytic activity toward nocamyin II. NcmD achieved maximum catalytic activity at 45°C and pH 8.5. The kinetics of NcmD toward nocamycin F was investigated at 45°C, pH 8.5 in the presence of 2 mM NAD+. The Km and kcat values were 131 ± 13 μM and 65 ± 5 min−1, respectively. In this study, we have characterized NcmD as a dehydrogenase, which is involved in forming the ketone group at the C-10 position of nocamycin F. The results provide new insights to the nocamycin biosynthetic pathway.

The Impact of Time-Restricted Diet on Sleep and Metabolism in Obese Volunteers

Background and objectives: A time-restricted diet is one of the various ways to improve metabolic condition and weight control. However, until now, there have been few pieces of evidence and research to verify the methods and effectiveness of time-restricted diets on metabolic improvement and health promoting. We designed this study to make a healthy diet program and to verify the effectiveness of a time-restricted diet on general health, including sleep and metabolism, in healthy volunteers. Materials and Methods: This study was conducted in healthy adults who are obese but do not have related metabolic disease. Fifteen participants were recruited. Before and after this program, serologic tests including ketone level, questionnaires—daytime sleepiness evaluation such as the Epworth sleepiness scale and the Stanford sleepiness scale, the Korean version of the Pittsburgh sleep questionnaire index, STOP BANG to evaluate sleep apnea, the Hospital Anxiety and Depression Scale for emotion/sleep—and polysomnography (PSG) were conducted to evaluate the effects on sleep of the program. They were divided into two groups based on ketone levels that could reflect the constancy of participation in this study. We analyzed the before and after results of each group. Results: Fifteen participants (nine males and six females) completed this program without significant adverse events. Body weight after this program decreased to 78.2 ± 14.1 from 82.0 ± 15.6 kg (p = 0.539), and BMI decreased to 27.9 ± 3.8 from 29.3 ± 4.6 kg/m2 (p = 0.233). Weight loss was observed in 14 subjects except 1 participant. The results from questionnaires before and after this were not significant changes. They were classified into high/low-ketone groups according to the ketone level of the participants. In the results of the PSG, the apnea hypopnea index (25.27 ± 12.67→15.11 ± 11.50/hr, p = 0.25) and oxygen desaturation (18.43 ± 12.79→10.69 ± 10.0/hr, p = 0.004), which are indicators of sleep apnea, also improved in the high-ketone group, compared with the low-ketone group. Satisfaction interviews for this restricted diet program showed that 86% of the participants were willing to participate in the same program again. Conclusion: The time-restricted diet was successful in weight loss for a period of 4 weeks in obese participants, which did not affect the efficiency and architecture of sleep. In addition, successful weight loss and significant improvement of sleep apnea were showed in the high-ketone group. Further research is needed to demonstrate mechanisms for weight loss, sleep apnea, and time-restricted diets.

Thermal Stability of Polyetherketones

The thermal stability of polyether ketone, polyetheretherketone, polyarylene ketone at 400-500 °C was studied by gas chromatography. It was found out that the thermal destruction of polyetherketones and polyetheretherketones begins with the rupture of the ketone group, and polyarylene ketones with the detachment of the methyl group and the rupture of the ether linkage of the diane fragment.

Temperature-regulated aggregation-induced emissive self-healable hydrogels for controlled drug delivery

Thermoresponsive copolymers TPE-[P(DMA-stat-DAA)]2 containing a tetraphenylethylene (TPE) moiety and a ketone group were synthesized.

Native and engineered clifednamide biosynthesis in multipleStreptomycesspp

ABSTRACTPolycyclic tetramate macrolactam (PTM) natural products are produced by actinomycetes and other bacteria. PTMs are often bioactive, and the simplicity of their biosynthetic clusters make them attractive for bioengineering. Clifednamide-type PTMs fromStreptomycessp. JV178 contain a distinctive ketone group, suggesting the existence of a novel PTM oxidizing enzyme. Here, we report the new cytochrome P450 enzyme (CftA) is required for clifednamide production. Genome mining was used to identify several new clifednamide producers, some having improved clifednamide yields. Using a parallel synthetic biology approach, CftA isozymes were used to engineer the ikarugamycin pathway ofStreptomycessp. NRRL F-2890 to yield clifednamides. Further, we observed that strong CftA expression leads to the production of a new PTM, clifednamide C. We demonstrate the utility of both genome mining and synthetic biology to rapidly increase clifednamide production and identify a PTM tailoring enzyme for rational molecule design.

Synthesis of 4H-3-aryl-2-cyano-1,4-benzothiazine 1,1-dioxides for antiviral studies

Abstract2-Cyano-substituted 1,4-benzothiazine 1,1-dioxides, required for antiviral studies, were prepared by a reductive cyclodehydration of an ortho-nitro sulfone precursor containing a pendant aryl ketone group. The ring-forming reaction also furnishes a non-cyclized benzamide as a major byproduct via an unexpected acyl transfer reaction.

Synthesis and Growth Stimulant Properties of 2-Acetyl-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidin-5-one Derivatives

A convenient, accessible, and high yield method for preparing of 6-methyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one (1) by treatment of acetoacetic acid ethyl ester with thiourea in sodium methylate was developed. The alkylation of the latter with 3-chloro-pentane-2,4-dione and further regioselective cyclization of intermediate compound (2) in high yield afforded 2-acetyl-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidin-5-one (3). The halogenation and some transformations of synthesized thiazolo[3,2-a]pyrimidine (3) due to its ketone group were carried out to obtain the corresponding carboxamide, carbothioamide, sulfonohydrazide, and oxime and its alkylated derivatives (5). At preliminary biological studies the synthesized compounds have shown growth stimulant properties. The activity of four of them was higher than 70%, compared with heteroauxin.