We examined the thymoquinone induced inhibition of purified F1 or membrane bound F1FO E. coli ATP synthase. Both purified F1 and membrane bound F1FO were completely inhibited by thymoquinone with no residual ATPase activity. The process of inhibition was fully reversible and identical in both membrane bound F1Fo and purified F1 preparations. Moreover, thymoquinone induced inhibition of ATP synthase expressing wild-type E. coli cell growth and non-inhibition of ATPase gene deleted null control cells demonstrates that ATP synthase is a molecular target for thymoquinone. This also links the beneficial dietary based antimicrobial and anticancer effects of thymoquinone to its inhibitory action on ATP synthase.

A new method to form a single gold nanoparticle (Au NP) is introduced. In our method, a single Au NP is spontaneously formed on the surface of a nanometer-sized platinum (Pt) electrode under open circuit potential. The single NP has been characterized by using Scanning Electron Microscopy and electrochemical methods. Electrochemical studies reveal that the small Au particle has extraordinary stability compared with that of a bulk Au phase. The extra stability of the Au NP is attributed to the formation of alloy with the Pt substrate.

In this paper we present the inhibitory effect of a variety of structurally modulated/modified polyphenolic compounds on purified F1 or membrane bound F1Fo E. coli ATP synthase. Structural modulation of polyphenols with two phenolic rings inhibited ATP synthase essentially completely; one or three ringed polyphenols individually or fused together inhibited partially. We found that the position of hydroxyl and nitro groups play critical role in the degree of binding and inhibition of ATPase activity. The extended positioning of hydroxyl groups on imino diphenolic compounds diminished the inhibition and abridged position enhanced the inhibition potency. This was contrary to the effect by simple single ringed phenolic compounds where extended positioning of hydroxyl group was found to be effective for inhibition. Also, introduction of nitro group augmented the inhibition on molar scale in comparison to the inhibition by resveratrol but addition of phosphate group did not. Similarly, aromatic diol or triol with rigid or planar ring structure and no free rotation poorly inhibited the ATPase activity. The inhibition was identical in both F1Fo membrane preparations as well as in isolated purified F1 and was reversible in all cases. Growth assays suggested that modulated compounds used in this study inhibited F1-ATPase as well as ATP synthesis nearly equally.

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A polyamine-zinc(ii) complex with an alcohol pendant promotes the hydrolysis of diethyl(4-nitropheny1)phosphate via transfer of the diethylphosphate group to its alkoxy pendant.

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In this paper, a nanometer-sized gold electrode with an effective radius around several tens of nanometers has been modified with a monolayer of alkanethiols. There are pinholes in the monolayer, and the pinholes can be used as very small electrode. Our evaluation shows that it is possible to have only one pinhole on the monolayer covered electrode. The single pinhole electrode has been used to study the electrochemical behaviors of fast and slow electrochemical reactions. Our results show that the electrochemical response of a slow electrochemical reaction is not a Butler-Volmer response if the electrode is small enough.