I'm having an issue with an enzyme I'm working with, where it catalyses its own inactivation over time, at an unknown rate. If i want to figure out some kinetic parameters for this, how could i do it? I've thought of trying to use Michaelis Menten kinetic assays, but as [S] = [E] i can't change just one of these variables. Any suggestions??
Tris(pentafluorophenyl)borane-catalyzed reactions between vinyl diazoacetates and aryl esters afforded highly regioselective N-alkylated pyrazoles. These reactions involve an autocatalytic process in which in situ formed carbenium species act as a catalyst to regioselectively afford pyrazoles. Detailed DFT studies were carried out to explain the reaction mechanism.
Abstract
In recent years, metal-free organic synthesis using triarylboranes as catalysts has become a prevalent research area. Herein we report a comprehensive computational and experimental study for the highly selective synthesis of N-substituted pyrazoles through the generation of carbenium species from the reaction between aryl esters and vinyl diazoacetates in the presence of catalytic tris(pentafluorophenyl)borane [B(C6F5)3]. DFT studies were undertaken to illuminate the reaction mechanism revealing that the in situ generation of a carbenium species acts as an autocatalyst to prompt the regiospecific formation of N-substituted pyrazoles in good to excellent yields (up to 81 %).
https://ift.tt/3AWq5q9
Hi all epic music fans :D I would really appreciate it if you listened to my new track "Autocatalytic," which will rocket you on a journey through the rise of modern technology. It is up-tempo, orchestral/rock influenced, bombastic, and most importantly, EPIC. Also link me your songs and I'd be glad to provide feedback. Cheers!
https://soundcloud.com/artifex_composer/autocatalytic
https://preview.redd.it/87kl9kbibn261.png?width=1420&format=png&auto=webp&s=e01a0b3eb51e0cc4c472b273355a16028a2d3f41
Under cover of nitrogen: Silyl‐protected aryl‐substituted diazenes act as masked aryl nucleophiles. Upon initiation with Me3SiOM (M=Li, Na, and K), aryl transfer to carbonyl and carboxyl groups occurs at ambient temperature. This mild nucleophile generation is compatible with electron‐withdrawing and electron‐donating functional groups.
Abstract
A method for the catalytic generation of functionalized aryl alkali metals is reported. These highly reactive intermediates are liberated from silyl‐protected aryl‐substituted diazenes by the action of Lewis basic alkali metal silanolates, resulting in desilylation and loss of N2. Catalytic quantities of these Lewis bases initiate the transfer of the aryl nucleophile from the diazene to carbonyl and carboxyl compounds with superb functional‐group tolerance. The aryl alkali metal can be decorated with electrophilic substituents such as methoxycarbonyl or cyano as well as halogen groups. The synthesis of a previously unknown cyclophane‐like [4]arene macrocycle from a 1,3‐bisdiazene combined with a 1,4‐dialdehyde underlines the potential of the approach.
https://ift.tt/3buOU02
Towards emergence of life : A domino sequence of events starts from traces of an enzyme triggering peptide generation, which is followed by self‐assembly into catalytic nanofibers that can induce and amplify their own production over time. This self‐sustained cycle leads to an autocatalytic self‐assembled buildup of a hydrogel.
Abstract
Autocatalysis and self‐assembly are key processes in developmental biology and are involved in the emergence of life. In the last decade both of these features were extensively investigated by chemists with the final goal to design synthetic living systems. Herein, we describe the autonomous growth of a self‐assembled soft material, that is, a supramolecular hydrogel, able to sustain its own formation through an autocatalytic mechanism that is not based on any template effect and emerges from a peptide (hydrogelator) self‐assembly. A domino sequence of events starts from an enzymatically triggered peptide generation followed by self‐assembly into catalytic nanofibers that induce and amplify their production over time, resulting in a 3D hydrogel network. A cascade is initiated by traces (10−18 m ) of a trigger enzyme, which can be localized allowing for a spatial resolution of this autocatalytic buildup of hydrogel growth, an essential condition on the route towards further cell‐mimic designs.
https://ift.tt/3guArn7
High‐entropy alloy (HEA) nanoparticles hold great promise as tunable catalysts, and surprisingly, Pt‐Ir‐Pd‐Rh‐Ru nanoparticles can be synthesized under benign low‐temperature solvothermal conditions. In situ X‐ray scattering and TEM reveal the solvothermal formation mechanism of Pt‐Ir‐Pd‐Rh‐Ru nanoparticles. The autocatalytic formation mechanism suggests that many types of HEA nanocatalysts should be accessible with scalable solvothermal reactions.
Abstract
High‐entropy alloy (HEA) nanoparticles hold great promise as tunable catalysts. Despite the fact that alloy formation is typically difficult in oxygen‐rich environments, we found that Pt‐Ir‐Pd‐Rh‐Ru nanoparticles can be synthesized under benign low‐temperature solvothermal conditions. In situ X‐ray scattering and transmission electron microscopy reveal the solvothermal formation mechanism of Pt‐Ir‐Pd‐Rh‐Ru nanoparticles. For the individual metal acetylacetonate precursors, formation of single metal nanoparticles takes place at temperatures spanning from ca. 150 °C for Pd to ca. 350 °C for Ir. However, for the mixture, homogenous Pt‐Ir‐Pd‐Rh‐Ru HEA nanoparticles can be obtained around 200 °C due to autocatalyzed metal reduction at the (111) facets of the forming crystallites. The autocatalytic formation mechanism suggests that many types of HEA nanocatalysts should accessible with scalable solvothermal reactions, thereby providing broad availability and tunability.
https://ift.tt/3aVKwY9
I recently learned from Periodic Videos that explosions are categorized as autocatalytic reactions, where the reaction accelerates itself, with violent results. I am curious if exothermicity plays a factor in these reactions, and if there is such a thing as an endothermic explosion?
Nature Chemistry, Published online: 23 March 2020; doi:10.1038/s41557-020-0421-8
The discovery of amplifying autocatalysis in a pyridine-3-carbaldehyde system facilitates a mechanistic deconstruction of the Soai reaction. A tetrameric autocatalyst, assembled by a combination of steric effects and nitrogen–zinc coordination, activates the substrate by two-point binding. This is followed by intra-complex isopropyl group transfer that generates the product alkoxide with high homochiral fidelity.
https://ift.tt/3dhgXRk
An autocatalytic circuit is constructed for in vivo fluorescence/molecular resonance imaging based on a hybridization chain reaction (HCR) and DNAzyme biocatalysis, sustained by a honeycomb MnO2 nanosponge (hMNS). The hMNS was not only used to deliver the DNA, but also to supply the DNAzyme with Mn2+ as a cofactor. This system was used to detect microRNA in vivo and shows great promise in cancer diagnosis.
Abstract
DNAzymes have been recognized as promising transducing agents for visualizing endogenous biomarkers, but their inefficient intracellular delivery and limited amplification capacity (including insufficient cofactor supply) preclude their extensive biological application. Herein, an autocatalytic DNAzyme (ACD) biocircuit is constructed for amplified microRNA imaging in vivo based on a hybridization chain reaction (HCR) and DNAzyme biocatalysis, sustained by a honeycomb MnO2 nanosponge (hMNS). The hMNS not only delivers DNA probes, but also supplies Mn2+ as a DNAzyme cofactor and magnetic resonance imaging (MRI) agent. Through the subsequent cross‐activation of HCR and DNAzyme amplicons, the ACD amplifies the limited signal resulting from miRNA recognition. The hMNS/ACD system was used to image microRNA in vivo, thus demonstrating its great promise in cancer diagnosis.
https://ift.tt/2RglE4Y
An interesting reading on the history of autocatalytic processes which dives a bit into the mathematics and philosophy of such processes. An excerpt: "Is life, then, an autocatalytic process?"
https://academic.oup.com/bioscience/article/63/11/877/2389920
Currently, the hazard shields allow you to stay outside in the hazard for longer before you start taking damage. However (and I might be mistaken) they never get so efficient and effective that you can simply ignore the hazard.
Furthermore, you still have to "recharge" them with zinc, titanium, or shielding shards.
Wouldn't it be cool if there was a technology to deal with a hazard that would allow you to meander across an alien swamp or desert feeling like you had really "gone native"?
In order to balance it, here are two drawbacks:
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Your autocatalytic hazard protection regenerates nonlinearly, with the peak regeneration rate in the middle (like Eve's shields). Spikes of incoming damage can "break" your protection, leading to "shelter from storms" and/or "shelter at night" policies.
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You can no longer use absolutely any isotope to recharge your life support. One way to do this is, if you want to charge your life support with C or Pu, you have to dismantle this tech first. Another way to do this is, if charge your life support with C or Pu, you also break your autocatalytic hazard tech, putting it into the "damaged" state.
So the experience is: You wander across an alien landscape, that less-well-equipped explorers cannot tolerate, alert for the various flowers (Th9, Shield, Health) that you need to survive in this landscape.
If this autocatalytic tech only existed for one of the four hazards, it would help distinguish that hazard from the others.
I don't want to step on anybody's toes here, but the amount of non-dad jokes here in this subreddit really annoys me. First of all, dad jokes CAN be NSFW, it clearly says so in the sub rules. Secondly, it doesn't automatically make it a dad joke if it's from a conversation between you and your child. Most importantly, the jokes that your CHILDREN tell YOU are not dad jokes. The point of a dad joke is that it's so cheesy only a dad who's trying to be funny would make such a joke. That's it. They are stupid plays on words, lame puns and so on. There has to be a clever pun or wordplay for it to be considered a dad joke.
Again, to all the fellow dads, I apologise if I'm sounding too harsh. But I just needed to get it off my chest.
Do your worst!
They were cooked in Greece.
I'm surprised it hasn't decade.
For context I'm a Refuse Driver (Garbage man) & today I was on food waste. After I'd tipped I was checking the wagon for any defects when I spotted a lone pea balanced on the lifts.
I said "hey look, an escaPEA"
No one near me but it didn't half make me laugh for a good hour or so!
Edit: I can't believe how much this has blown up. Thank you everyone I've had a blast reading through the replies 😂
It really does, I swear!
Autocatalysis and self‐assembly are key processes in developmental biology and are involved in the emergence of life. In the last decade both features were extensively investigated by chemists with the final goal to design synthetic living systems. Herein, we describe the autonomous growth of a self‐assembled soft material, i.e. a supramolecular hydrogel, able to sustain its own formation through an autocatalytic mechanism not based on any template effect and emerging from a peptide (hydrogelator) self‐assembly. A domino sequence of events starts from an enzymatically triggered peptide generation followed by their self‐assembly into catalytic nanofibers inducing and amplifying their production over time, resulting in a 3D hydrogel network. A cascade is initiated by traces (10‐18 M) of a trigger enzyme which can be localized allowing for a spatial resolution of this autocatalytic buildup, a sine qua none condition to fulfil on the route toward further cell mimic designs.
https://ift.tt/3guArn7
A method for the catalytic generation of functionalized aryl alkali metals is reported. These highly reactive intermediates are liberated from silyl‐protected aryl‐substituted diazenes by the action of alkali metal silanolates, resulting in desilylation and loss of N2. Catalytic quantities of these Lewis bases initiate the transfer of the aryl nucleophile from the diazene to carbonyl and carboxyl compounds with superb functional‐group tolerance. The aryl alkaline metal can be decorated with electrophilic substituents such as methoxycarbonyl or cyano as well as halogen groups. The synthesis of an unknown cyclophane‐like [4]arene macrocycle from a 1,3‐bisdiazene combined with a 1,4‐dialdehyde underlines the potential of the approach.
https://ift.tt/3buOU02
