Regeneration Triggering

Preparation of semisynthetic aequorins. The best yield of semisynthetic aequorins can be obtained by using the apoaequorin prepared from aequorin immediately before use. Apoaequorin stored, even for 2-3 days, or recombinant apoaequorin isolated from a bacterial culture will give a significantly lower yield due to their somewhat unfolded molecular conformation. Fresh apoaequorin prepared by the Ca2+-triggered luminescence reaction appears to have the conformation best suited for regeneration. 

Very recently, Murakami has published an Rh(i)-catalyzed cyclization of 1,6-enynes triggered by addition of arylboronic acids (Scheme 74).281 Initial carborhodation of the alkyne moiety is followed by insertion into the alkene moiety. /3-Alkoxy elimination provides the final product 289 in good yield and regenerates the catalyst species. 

The present discussion is only concerned with the structure/redox capacity of the site responsible for the oxidation of water. The starting point is the evidence that the photosynthetic pathway is triggered by photooxidation of the chlorophylls in photosystem II. The need for chlorophylls to recover the electrons lost in photooxidation (in order to regenerate their ability to absorb light) induces water to undergo oxidation, according to ... 

A variety of amines have been used as mediators for electrochemical oxidation reactions. In these reactions, the amine is oxidized at an anode surface to form a radical cation. The amine radical cation then oxidizes a second substrate triggering a reaction of synthetic interest. The regenerated amine is then reoxidized at the anode... 

Catalytic Oxidation of NAD(P)H A Continuously Improved Selection of Suitable ROMs This research is triggered hy at least two reasons (1) the importance of NAD(P)H/NAD(P)- - redox couples in biological systems is known, as is known the dependence of oxidation mechanisms on the oxidants [14, 82, 172-174] (2) the possibility of developing amperometric biosensors for NAD(P)+-dependent dehydrogenases. As a consequence, much attention is devoted to the regeneration of these coenzymes in their reduced or oxidized forms for their application in biosensors or in enzymatic synthesis [180]. Here, we are concerned with electrochemical regeneration [181]. 

This idea was probed by irradiating two samples of CN-DHA with the same concentration and volume in a one pump pulse and a two pump pulses experiment [7] In the one pulse experiment the photoconversion to CN-VHF-trans was triggered at 340 nm under similar conditions as in the two color time resolved measurements. The irradiation time t was chosen such that a significant amount of CN-VHF-trans was converted. In the two pulses experiment an additional pulse at 530 nm which was delayed by 25 ps from the first pulse excited the transient CN-VHF-cis for the same time t. After the irradiation much less CN-VHF-trans is found in the two pulse experiment than in the one pulse experiment (Fig. 4). We conclude that a significant amount of CN-DHA was regenerated from the transient species by the second pulse. Photodegradation and thermal activation by the 530 nm pulses were eliminated as possible reasons for the observed effect. 

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