Organic & Biomolecular Chemistry Blog

HOT: Sensing cysteine only for health tests

15 Mar 2012

A sensing system to detect cysteine (Cys), an essential amino acid, has been developed by scientists in the US and China. Elevated levels of Cys have been associated with neurotoxicity, while Cys deficiency is involved in a number of other disorders.

The sensing system works as a fluorescent chemodosimeter, which displays discrimination for cysteine over commonly occurring analytes that would be expected to co-exist in real samples, such as homocysteine and glutathione. Moreover, the system is desirable in that it displays off-to-on response to the target analyte and does so at a desirable long wavelength, which minimises potential interference by endogenous chromophores.

Due to its simplicity and very high selectivity, this chemodosimeter can be used to detect Cys at physiological levels.

Highly rated by the reviewers and Editorial office alike, this article has been selected as ‘Hot’ and will be FREE to access for the next 4 weeks – why not read it now!

A seminaphthofluorescein-based fluorescent chemodosimeter for the highly selective detection of cysteine
Xiaofeng Yang, Yixing Guo and Robert M. Strongin
Org. Biomol. Chem., 2012, Advance Article
DOI: 10.1039/C2OB25178G, Communication

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HOT: Probing the effects of a novel post-translational modification on synaptic protein binding

13 Mar 2012

By James Anson.

In this HOT OBC Communication Mark E. Graham, Richard J. Payne and co-workers probe the effect of a recently discovered post-translational modification of threinine of the assembly protein AP180, a protein which plays a crucial role in clathrin coated vesicle formation in synaptic vesicle endocytosis.

Using pull down experiments on AP180 peptide fragments they aimed to explore how binding to proteins in rat brain lysate is influenced by this modification.

Read the article to find out more about the peptides used and the effect of this modification on the affinity towards synaptic proteins.

Go on, it’s FREE to access for the next 4 weeks!

Synthesis and protein binding studies of a peptide fragment of clathrin assembly protein AP180 bearing an O-linked β-N-acetylglucosaminyl-6-phosphate modification
Mark E. Graham, Robin S. Stone, Phillip J. Robinson and Richard J. Payne
Org. Biomol. Chem., 2012, 10, 2545-2551
DOI: 10.1039/C2OB07139H

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Asymmetric catalytic Mannich-type reaction of hydrazones using Zn(II) complexes on the cover of OBC issue 13

12 Mar 2012

By James Anson.

The cover of this week’s OBC features work from Min Shi et al. at Shanghai Institute of Organic Chemistry and Texas Tech University, who have used chiral zinc(II)–imidazoline–phosphine complexes in a novel catalytic system for the asymmetric Mannich-type difluorination of hydrazones with difluoroenoxysilanes.

Asymmetric catalytic Mannich-type reaction of hydrazones with difluoroenoxysilanes using imidazoline-anchored phosphine ligand–zinc(II) complexes
Zhiliang Yuan, Liangyong Mei, Yin Wei, Min Shi, Padmanabha V. Kattamuri, Patrick McDowell and Guigen Li
Org. Biomol. Chem., 2012, 10, 2509-2513
DOI: 10.1039/C2OB07022G

Read the full Communication; it is FREE to access for the next 6 weeks.

This issue also contains:

A Perspective review article: On a so-called “kinetic anomeric effect” in chemical glycosylation, by Ian Cumpstey

as well as the HOT article:

If you liked these why not have a look at the rest of the issue here

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Room temperature syntheses of substituted beta-fluorofurans on the cover of OBC issue 12

08 Mar 2012

By Marie Cote, Deputy Editor.

On the cover this week is work by Roman Dembinski et al. at Oakland University and Eastern Illinois University, highlighting facile synthetic methods for the preparation of 3-fluorofurans, 3-bromo-4-fluorofurans, and 3-fluoro-4-iodofurans in good yields and at room temperature.

Read all about the synthetic sequences employed: this article will be FREE to access for a period of 6 weeks.

Room temperature syntheses of entirely diverse substituted β-fluorofurans
Yan Li , Kraig A. Wheeler and Roman Dembinski
Org. Biomol. Chem., 2012, 10, 2395-2408
DOI: 10.1039/C1OB06693E

Also in this issue, take a look at a hot article by Taku Shoji et al. presenting novel developments in the field of donor-acceptor chromophores, which can be synthesised using the [2+2] cycloaddition-cycloreversion (CA/CR) reaction; or read a timely Perspective showcasing recent advancement in the stereoselective synthesis of 2-C-branched sugar analogs, by Torsten Linker et al., and much more!

View the full issue here

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Join ICPO21: 21st IUPAC International Conference on Physical Organic Chemistry

01 Mar 2012

By Richard Kelly.

The Organic Division of the RSC on behalf of IUPAC is now inviting contributions to ICPO21: 21^st IUPAC International Conference on Physical Organic Chemistry to be held 9 – 13 September 2012 at Durham University.

The submission deadline dates are:

Oral abstracts 23 March 2012
Poster abstracts 13 July 2012

Key topics that will be covered in the meeting include:

Physical underpinnings
Mechanism and Catalysis
Supramolecular and Systems Chemistry

Why join ICPOC21?

A broad range of scientists from across the whole community who share a quantitative perspective on chemistry will be there, providing an opportunity to discuss and celebrate the current status, development, and the future of physical organic chemistry.

In addition to outstanding plenary sessions, there will be three parallel sessions over the five days comprising invited lectures and contributed talks, as well as poster sessions.

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RSC Publishing poster prizes awarded at ISMSC

27 Feb 2012

By Marie Cote, Deputy Editor.

Congratulations to the following students who were awarded ChemComm, Dalton Transactions and Organic & Biomolecular Chemistry poster prizes at the 2012 International Symposium on Macrocyclic and Supramolecular Chemistry (ISMSC) at the University of Otago in Dunedin, New Zealand:

Jean-Francois Ayme (Edinburgh) – “Pentameric Circular Helicates as a Scaffold for a Molecular Pentafoil Knot”
Jessica Holmes (Melbourne) – “Supramolecular Systems of Cyclotricatechylene”
David Hvasanov (UNSW) – “Photoinduced membrane proton-pumping via polymersomes as chloroplast mimics”

The poster prize winners with Professor Phil Gale from the ISMSC-2012 International Advisory Committee (photo courtesy of Scott Cameron from the Brooker group)

Nominations for the 2013 Cram Lehn Pedersen prize to be awarded at ISMSC-8 in Crystal City, Virginia, USA, will open later in the year. Stay tuned to the ChemComm blog for details.

Related news:
Cram Lehn Pedersen Prize awarded at ISMSC

Posted on behalf of Joanne Thomson

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Computers look at life-giving reactions in space

24 Feb 2012

By Nathalie Horner.

Theoretical chemistry could answer some questions about how life on earth originated, say Australian researchers.

Although we know amino acids were vital in the genesis of life, how they first appeared on earth is still under much debate. One theory is that they were introduced from space, having been synthesised in molecular clouds from simpler radicals. However, at almost absolute zero temperatures, it would be very difficult for any molecular collision to overcome the activation energy barrier. Unfortunately, owing to these extreme conditions, it is impossible to conduct laboratory experiments to investigate this.

Noticing that a number of possible interstellar reactions involve hydrogen transfer, John Bowie and Tianfang Wang at the University of Adelaide considered the possibility that they may be assisted by hydrogen tunnelling effects. Hydrogen tunnelling occurs when hydrogen atoms or nuclei take part in a reaction without having to overcome an energy barrier; instead they ‘tunnel’ through it. The team used high level computational methods to study how tunnelling affects isomerisation reactions that may either help or hinder the synthesis of biologically important molecules.

Molecules of life are thought to have been introduced to earth by collisions from comets or meteorites

‘Let us propose, for example, that ?CH₂NH₂and ?CN react to form the glycine precursor NH₂CH₂CN,’ explains Bowie, ‘if [?CH₂NH₂] isomerises rapidly to CH₃NH?, then the proposed synthesis is not practical.’

They found that although these reactions show significant tunnelling effects, the rate constants for most of them would still be too slow for reaction to occur.

Holger Somnitz, a theoretical chemistry expert at the University of Duisburg-Essen, Germany, appreciates the information obtained. ‘The [researchers] have quantified the effect of tunnelling. and provided valuable information on the potential energy along the minimum energy path,’ he says. However, he points out that the true impact of the work will only be revealed after experimental confirmation of the interstellar existence of the studied radicals.

Recognising the usefulness of the information obtained from their calculations, the researchers are now turning their attention to tunnelling effects in other fields of interest, such as in proteomics.

Hydrogen tunnelling influences the isomerisation of some small radicals of interstellar importance. A theoretical investigation.
Tianfang Wang and John H. Bowie
DOI: 10.1039/C2OB07102A

Read the original article at Chemistry World

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HOT: Uncovering a key enzyme in antibiotic D-cycloserine biosynthesis

24 Feb 2012

By Marie Cote, Deputy Editor.

In this OBC ‘Hot paper’ John C. Vederas and coworkers describes studies on a key enzyme (DscC) in the biosynthesis of the important antibiotic D-cycloserine – commonly used against Mycobacterium tuberculosis when resistance to other antibiotics is observed.

The enzyme is proposed to be an epimerase based on sequence similarity to a known enzyme DapF (diaminopimelate epimerase), and the authors show that DscC indeed displays the predicted activity, namely O-ureidoserine racemization.

The determination of the 3D stucture of the enzyme is underway.

‘Comparison of the enzymatic residues that are responsible for recognition of the non-reacting distal site of the enzyme could lead to the ability to rationally design enzymes that can induce epimerization of other amino acids’, conclude the authors.

Read more and access the full article here – FREE to download for a period of four weeks!

Characterization of DcsC, a PLP-independent racemase involved in the biosynthesis of D-cycloserine
David Dietrich, Marco J. van Belkum and John C. Vederas
Org. Biomol. Chem., 2012, 10, 2248-2254
DOI: 10.1039/C2OB06864H,

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Hot Perspective: Using trichlorosilane for the organocatalysed reduction of ketimines

24 Feb 2012

By Marie Cote, Deputy Editor.

Following the recent highlight of topical reviews in OBC, here is our latest ‘Hot Perspective’:

read about the most advanced developments on Trichlorosilane mediated asymmetric reductions of the C=N bond in this review article by Simon Jones and Christopher J. A. Warner.

Concise but thorough, the review will take you through efficient and economical ways to access chiral amines via the trichlorosilane mediated organocatalytic reduction of ketimines, and provide a direct quantitative comparison to transition-metal mediated process.

Trichlorosilane mediated asymmetric reductions of the C=N bond
Simon Jones and Christopher J. A. Warner
Org. Biomol. Chem., 2012, 10, 2189-2200
DOI: 10.1039/C2OB06854K, Perspective

This Perspective will be FREE to access for the next 4 weeks

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Organic & Biomolecular Chemistry Blog

HOT: Sensing cysteine only for health tests

HOT: Probing the effects of a novel post-translational modification on synaptic protein binding

Asymmetric catalytic Mannich-type reaction of hydrazones using Zn(II) complexes on the cover of OBC issue 13

Room temperature syntheses of substituted beta-fluorofurans on the cover of OBC issue 12

Join ICPO21: 21st IUPAC International Conference on Physical Organic Chemistry

RSC Publishing poster prizes awarded at ISMSC

Computers look at life-giving reactions in space

HOT: Uncovering a key enzyme in antibiotic D-cycloserine biosynthesis

Hot Perspective: Using trichlorosilane for the organocatalysed reduction of ketimines

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