A switching cascade of hydrazone-based rotary switches through coordination-coupled proton relays

Imidazole, a subunit of histidine, plays a crucial role in proton-relay processes that are important for various biological activities, such as metal efflux, viral replication and photosynthesis. We show here how an imidazolyl ring incorporated into a rotary switch based on a hydrazone enables a swi...

Full description

Saved in:
Bibliographic Details
Published in:Nature chemistry 2012-09, Vol.4 (9), p.757-762
Main Authors: Ray, Debdas, Foy, Justin T., Hughes, Russell P., Aprahamian, Ivan
Format: Article
Language:English
Subjects:
639/638/403
639/638/541/911
Analytical Chemistry
Biochemistry
Chemical Phenomena
Chemistry
Chemistry/Food Science
Coordination
Crystallography, X-Ray
Efflux
Histidine
Histidine - chemistry
Hydrazones
Hydrazones - chemistry
Hydrogen bonds
Imidazole
Imidazoles - chemistry
Inorganic Chemistry
Isomerism
Isomerization
Magnetic Resonance Spectroscopy
Molecular Conformation
Organic Chemistry
Photosynthesis
Physical Chemistry
Protons
Pyridines
Relay
Static Electricity
Switches
Switching
Zinc
Zinc - chemistry
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Imidazole, a subunit of histidine, plays a crucial role in proton-relay processes that are important for various biological activities, such as metal efflux, viral replication and photosynthesis. We show here how an imidazolyl ring incorporated into a rotary switch based on a hydrazone enables a switching cascade that involves proton relay between two different switches. The switching process starts with a single input, zinc( II ), that initiates an E / Z isomerization in the hydrazone system through a coordination-coupled proton transfer. The resulting imidazolium ring is unusually acidic and, through proton relay, activates the E / Z isomerization of a non-coordinating pyridine-containing hydrazone switch. We hypothesize that the reduction in the acid dissociation constant of the imidazolium ring results from a combination of electrostatic and conformational effects, the study of which might help elucidate the proton-coupled electron-transfer mechanism in photosynthetic bacteria. Metal cations play an important role in biological proton relays by modulating the p K a values of surrounding amino acids. This effect has now been used to induce the isomerization of two hydrazone switches using a single input. It is found that a combination of electrostatic repulsion and conformational changes are required for the proton relay to take place.
ISSN:1755-4330
1755-4349
DOI:10.1038/nchem.1408