Synthetic Studies toward Aziridinomitosenes and 9-Oxo-pyrrolo[1,2-a]indole Mitosanes Related to the Mitomycin and FR Heterocycles.

The aminobenzoquinone mitomycins and the dihydrobenzoxazine FR compounds are potent antitumor antibiotics. Despite structural differences, the compounds are reductively activated to analogous reactive metabolites known as leucoaziridinomitosenes. Leucoaziridinomitosenes contain two electrophilic sites at the C(1) and C(10) positions which are selectively attacked by two guanosines on complementary strands of DNA, thereby resulting in cross-link formation and cell death. Much has been learned about the complex mechanism of action of these compounds, but a better understanding of their mechanisms of action and biological origins is required in order to produce more potent and less cytotoxic synthetic analogs. The leucoaziridinomitosene derived from the semisynthetic derivative FK317 was targeted for total syntheses. The tetracyclic core of the target was accessed via intramolecular Michael addition of a chiral lithioaziridine into a vinylogous amide. Temporary protection of a stabilizing formyl group, reduction of an enoate, and subsequent transformation of the resulting alcohol provides the free C(10) carbamate. The C(10) carbamate of the intact leucoaziridinomitosene proved to be extremely labile as it was lost under acidic, basic, and neutral conditions which were explored to remove the final aziridine protecting group. Surprisingly, in contrast to the mitomycin leucoaziridinomitosenes, C(10) heterolysis of the FR leucoaziridinomitosenes was more facile than C(1) heterolysis. Nonetheless, a fully functionalized leucoaziridinomitosene derivative of FK317 was obtained. In order to probe the related biosynthetic pathways of mitomcyin C and FR900482, a mitosane derivative that could be a common precursor of both structural families was targeted for synthesis. Multiple strategies for tetracycle construction focused on addition of a lithioaziridine into an appropriate electrophile. The successful strategy employed a palladium catalyzed coupling of a 3,6-diazabicyclo[3.1.0]hexan-2-one to a functionalized aryl triflate, followed by diastereoselective cyclization to the desired stereoisomer of the tetracycle via carbanion addition into an appended lactam. The top face of the tetracycle is blocked by the large aziridine protecting group, which should facilitate diastereoselective reductive cleavage of a C(9) leaving group from the bottom face of the tetracycle to form the required C(9) stereochemistry. These studies culminated in the successful synthesis of a fully functionalized 9-oxo-pyrrolo[1,2a]indole mitosane derivative of the mitomycins and FR compounds.Ph.D.ChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/64647/1/deetersu_1.pd

Origins Space Telescope science drivers to design traceability

The Origins Space Telescope (Origins) concept is designed to investigate the creation and dispersal of elements essential to life, the formation of planetary systems, and the transport of water to habitable worlds and the atmospheres of exoplanets around nearby K-and M-dwarfs to identify potentially habitable-and even inhabited-worlds. These science priorities are aligned with NASA\u27s three major astrophysics science goals: How does the Universe work? How did we get here? and Are we alone? We briefly describe the science case that arose from the astronomical community and the science traceability matrix for Origins. The science traceability matrix prescribes the design of Origins and demonstrates that it will address the key science questions motivated by the science case

Origins Space Telescope: Baseline mission concept

The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid-and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20 μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588 μm, making wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins\u27 natural background-limited sensitivity

Origins Space Telescope: baseline mission concept

The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid- and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20  μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250  μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588  μm, making wide-area and deep spectroscopic surveys with spectral resolving power R  ∼  300, and pointed observations at R  ∼  40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins’ natural background-limited sensitivity

Reactivity of Aziridinomitosene Derivatives Related to FK317 in the Presence of Protic Nucleophiles

The syntheses and reactivity of <i>N</i>-TBDPS and <i>N</i>-trityl protected derivatives of an aziridinomitosene corresponding to FK317 are described. New reactivity patterns were observed for these highly sensitive and functionally dense heterocycles under mild nucleophilic conditions approaching the threshold for degradation. Thus, the silyl or trityl protected aziridinomitosene reacted with Cs₂CO₃/CD₃OD to give isomeric products where substitution occurred at C(10) and C­(9a) (mitomycin numbering) providing a CD₃ ether and a CD₃ hemiaminal, respectively. These findings show that heterolysis at C(10) is faster than at aziridine C(1), in contrast to the behavior of typical aziridinomitosenes in the mitomycin series. The labile <i>N</i>-TBDPS hemiaminal and the more stable <i>N</i>-trityl hemiaminal resemble the mitomycin K substitution pattern. A reagent consisting of CsF in CF₃CH₂OH/CH₃CN desilylated a simple <i>N</i>-TBDPS aziridine but caused nucleophilic cleavage at C(1) as well as C(10) without cleavage of the <i>N-</i>TBPDS group in the fully functionalized penultimate aziridinomitosene. The high reactivity of the C(10) carbamate with nucleophiles precludes the use of deprotection methodology that requires <i>N</i>-protonation for fully functionalized aziridinomitosenes in the FK317 series

Activity-Based Protein Profiling Reveals Mitochondrial Oxidative Enzyme Impairment and Restoration in Diet-Induced Obese Mice

<div><p>High-fat diet (HFD) induced obesity and concomitant development of insulin resistance (IR) and type 2 diabetes mellitus have been linked to mitochondrial dysfunction. However, it is not clear whether mitochondrial dysfunction is a direct effect of a HFD, or if mitochondrial function is reduced with increased HFD duration. We hypothesized that the function of mitochondrial oxidative and lipid metabolism functions in skeletal muscle mitochondria for HFD mice are similar, or elevated, relative to standard diet (SD) mice; thereby, IR is neither cause nor consequence of mitochondrial dysfunction. We applied a chemical probe approach to identify functionally reactive ATPases and nucleotide-binding proteins in mitochondria isolated from skeletal muscle of C57Bl/6J mice fed HFD or SD chow for 2-, 8-, or 16-weeks; feeding time points known to induce IR. A total of 293 probe-labeled proteins were identified by mass spectrometry-based proteomics, of which 54 differed in abundance between HFD and SD mice. We found proteins associated with the TCA cycle, oxidative phosphorylation (OXPHOS), and lipid metabolism were altered in function when comparing SD to HFD fed mice at 2-weeks, however by 16-weeks HFD mice had TCA cycle, β-oxidation, and respiratory chain function at levels similar to or higher than SD mice.</p> </div

Comparison of citrate synthase activity measured by an activity assay and by LC-MS based ABPP using ATP-ABP

<p>. (A) The citrate synthase activity was measured for each skeletal muscle mitochondrial lysates from individual mice. Results show the mean +/− standard error. (B) Protein abundance identified by <b>ATP-ABP</b> labeling of citrate synthase. Results show the mean of the abundance measured by MS +/− standard error. A single outlier at 2- and 16-week time points was removed from the HFD group. Each box in (A) and (B) contains all measured data for each point. The line within the box indicates the mean, and capped dashed lines represent the standard error from the mean.</p

Activity-based protein profiling of skeletal muscle mitochondria with ATP-ABP.

<p>(A) Probe structure of <b>ATP-ABP</b>, and reactivity with ATPases and ATP-binding proteins. The ε-amino group of lysine reacts with the mixed anhydride of <b>ATP-ABP</b> to form a stable amide bond on the protein to a six-carbon moiety containing the click chemistry (CC) compatible alkyne. Subsequent CC reaction to biotin-azide permits enrichment of <b>ATP-ABP</b>-labeled proteins. (B) Sample preparation of <b>ATP-ABP</b> labeled skeletal muscle mitochondrial proteins. Mitochondria were extracted from skeletal muscle tissue from individual mice, labeled with the probe (pink square), captured on streptavidin agarose resin (yellow circle), digested on-resin with trypsin, and the subsequent peptides were measured by LC-MS/MS.</p

Comparison of cytochrome C oxidase activity between HFD- and SD-fed mice at two weeks, measured by an absorbance assay.

<p>The cytochrome C oxidase activity was measured for each skeletal muscle mitochondrial lysate from individual mice. Results show the mean +/− standard error. A single outlier for both HFD- and SD-fed mouse groups was removed. The fold change closely correlates with the fold change for COX41 measured by <b>ATP-ABP</b> (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047996#pone-0047996-g003" target="_blank"><b>Figure 3</b></a>).</p

Ingenuity Pathway Analysis of 293 proteins labeled by <b>ATP-ABP</b> in mouse skeletal muscle mitochondria lysates from HFD and SD fed mice for 2-, 8-, and 16-weeks.

<p>The <i>p</i>-value indicates the significance of pathway enrichment. The ratio is the number of proteins identified by probe-labeling to the number of proteins assigned to that pathway by IPA.</p