Enzymatic synthesis of an indole diterpene by an oxidosqualene cyclase: mechanistic, biosynthetic, and phylogenetic implications

Petromindole (1) is an unusual indole diterpene that bears a triterpene-like carbon skeleton, suggesting biogenesis from 3-(omega-oxido-geranylgeranyl)indole (4). We found that lupeol synthase (LUP1) from Arabidopsis thaliana cyclizes 4 to 1. Chiral HPLC comparisons of racemic 1 (from biomimetic cyclization of N-pivaloyl-4) with the LUP1 product and authentic 1 established the absolute stereochemistry of petromindole (3S) as that of cyclic triterpenes. Quantum mechanical calculations and conformational analysis of intermediates in the cyclization of 4 to 1 indicated that petromindole biosynthesis differs fundamentally from that of other indole diterpenes. This analysis revealed that radarins also originate from cyclization of 4 but undergo a backbone rearrangement rather than annulation to indole. The combined results support our hypothesis that native fungal petromindole synthase evolved from a pentacyclic triterpene synthase distant from most other indole diterpene synthases.     

Reversed-phase HPLC of polymer additives with multiple on-line spectroscopic analysis (UV,IR, (1)H NMR and MS)

The reversed-phase chromatography of a number of polymer additives has been undertaken with on-line characterisation via a combination of diode array UV, (1)H NMR, IR spectroscopy and mass spectrometry. This combination of spectrometers enabled the on-flow collection of full UV, (1)H NMR, IR and mass spectra for a range of common polymer additives in amounts ranging from ca. 230 to 900 micro g on-column. The practical difficulties associated with multiple hyphenation and potential future developments are discussed.     

Neither first countable nor Cech-complete spaces are maximal Tychonoff connected

A connected Tychonoff space is called maximal Tychonoff connected if there is no strictly finer Tychonoff connected topology on . We show that if is a connected Tychonoff space and locally separable spaces, locally \v{C}ech-complete spaces, first countable spaces, then is not maximal Tychonoff connected. This result is new even in the cases where is compact or metrizable.

     

HZE beam transport in multilayered materials

A nonperturbative analytic solution of the high charge and energy (HZE) Green's function is used to implement a computer code for laboratory ion beam transport in multiple-layered materials. The code is established to operate on the Langley nuclear fragmentation model used in space engineering applications. Computational procedures are established to generate linear energy transfer (LET) distributions for a specified ion beam and target for comparison with experimental measurement. Comparison with 56Fe ion with Pb-Al and Pb-(CH2)x targets shows reasonable agreement.     

High-performance liquid chromatographic determination of Tornalate in solution dosage forms; a specificity study

A reversed-phase high-performance liquid chromatographic method has been applied utilizing ion-pairing to measure Tornalate in solution dosage forms. Specificity of the method was demonstrated by selectivity for Tornalate analysis, analysis of stressed samples and by peak homogeneity tests. These included the diode-array derived spectral overlay test and fraction collection with rechromatography in an alternate normal phase system. Linearity was also demonstrated in terms of recovery from synthetic samples and detector response.     

Blends of cellulose ester/phenolic polymers – chemical and thermal properties of blends with polyvinyl phenol

A series of miscible cellulose ester/poly (vinyl phenol) (CE/PVP) blends containing a latent formaldehyde source were prepared. Due to the low molecular weight of the PVP, the maximum PVP content ID the films was 50 wt %. The blends were then thermally cross-linked ID an attempt to create semi-interpenetrating polymer networks (semi-IPN). The blends were characterized with differential scanning calorimetry, swelling experiments, pyrolysis molecular beam mass spectrometry (py-MBMS), and Fourier transform infrared (FTIR) spectroscopy. The results from the swelling experiments, py-MBMS and FTIR showed that the PVP component did react with the formation of methylene bridges. Blends that contained 50% PVP and high levels of formaldehyde formed semi-IPN structures.     

Mass spectra of N and O methyl and methylthiomethyl derivatives of benzophenone oxime

The mass spectra of benzophenone oxime O-methyl and O-methylthiomethyl ethers, α,α-diphenyl-N-methyl and methylthiomethyl nitrones, and some deuterated analogues, are reported. Fragmentation pathways are discussed, with particular reference to the structures of ion m/e 211 found in all the spectra. Some evidence suggests nitrone → O-ether rearrangement at either neutral molecule or molecular ion level.