Chemical Science Blog

Scientists have converted a protein from a pathogenic bacterium into a FRET-based fluorescent probe to help find out why bismuth therapeutics can treat gastric illnesses.

Helicobacter pylori is a bacterium that colonises the digestive track and causes chronic gastritis, ulcers and even some gastric cancers. Bismuth-containing medicines are known treatments for H. pylori. It is thought that bismuth ions bind to metal binding sites in H. pylori’s metalloproteins but their exact mechanism of action is unknown.

Chuan He and colleagues at the University of Chicago investigated the metal binding properties of their FRET probe, made from the Hpn protein found in H. pylori, with different biometals in vitro. They showed that the sensor has a high affinity for Ni²⁺ and Zn²⁺ and moderate affinity for Bi³⁺. They then used the sensor in E. coli cells, which act as a model system for H. pylori, to measure uptake of these three ions. To their surprise, E. coli concentrated significant amounts of Bi³⁺, but not Ni²⁺ or Zn²⁺.

If Bi³⁺ accumulates to similarly high levels in H. pylori, says He, it may target Hpn, eventually killing the bacteria.

Read the Edge article online today and let us know what you think of this work by leaving your comments below.

Confining enzymes in a small container increases overall reaction rates but the increase is independent of the number of enzymes encapsulated, claim scientists in the Netherlands. 

Jeroen Cornelissen, at the University of Twente, and colleagues used the capsid of the Cowpea Chlorotic Mottle virus to encapsulate enzymes, mimicking the crowded environment enzymes experience in a cell. They found that encapsulated enzymes have a higher activity than free enzymes, which they say is caused by the high confinement molarity of the enzyme and the increased collision rate with its substrate. 

But increasing the number of enzymes inside the capsid does not increase the reaction rate, says Cornelissen. A capsid rarely contains more than one substrate molecule so one enzyme is sufficient to convert the substrate, he explains.

Want to learn more about the art of confinement? Read the Edge article for free online.

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The Ruddlesden-Popper structure is an archetypal structure in solid state chemistry, consisting of slabs of perovskite units separated by rock salt layers. But conventional high temperature oxide synthesis methods can’t be used to make these structures when the perovskite blocks are greater than three octahedral thick.

Now Matthew Rosseinsky, at the University of Liverpool, UK, and colleagues have exploited the capabilities of modern thin film deposition to grow an artificial metastable oxide where the perovskite block is six octahedral thick and is made of two distinct perovskite units.

Find out more in their Chemical Science Edge article and let us know your comments on the work below.

That’s it. British summertime is officially over. So to help us through the cold, dark winter, I’ve collected together some of the hottest Edge articles published in October.

Bright results
Oligomeric tandem terpyridyl platinum(II) complexes display spectacular solvent dependent emission properties and self-aggregating behaviour. What factors govern this strong emissive property? Find out in Chi-Ming Che’s Edge Article.

Catalytic water oxidation
Robert Crabtree and colleagues report a new method for generating an amorphous electrodeposited material, principally consisting of iridium and oxygen, which is a robust and long-lived catalyst for water oxidation, when driven electrochemically.

Forming C-C bonds
A novel method for the direct, amine-catalysed, highly enantioselective α-alkylation of aldehydes has been discovered by Claudio Palomo and colleagues. Find out more about the reaction conditions and mechanism.

Extending cyclopropenium activation
Geminal dichlorocyclopropenes rapidly and efficiently convert oximes to amides at room temperature, with reactivity that far surpasses other organic-based promoters, report Tristan Lambert and colleagues in their Edge article.

Understanding aerobic oxidation
Experimental and computational data provide direct evidence for two parallel mechanistic pathways for O₂ insertion into a Pd–H bond, claim Shannon Stahl and colleagues. Assess the evidence for yourself in their Edge Article.

Gauging electronic dissymmetry
What kinds of environments give rise to effective levels of electronic dissymmetry in metal complexes? Seth Brown and colleagues investigate the behaviour of a series of tetrasubstituted biphenolates with substituents of varying electronic and steric character and shed light on the origins of stereoselectivity in these complexes. Read more…

Easy access to polycyclic ring systems
Daniel Seidel and colleagues report a new 1,6-annulation reaction for azomethine ylides which could find widespread use in alkaloid synthesis.

Catalytic nitrene transfer
Alan Heyduk and colleagues report on the catalytic formation of carbodiimide using zirconium(IV) bearing a redox-active ligand.

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