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2010

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(9H-Fluoren-9-yl)methanethiol

[957753-00-3] C14H12S (MW 212.32)
InChI = 1S/C14H12S/c15-9-14-12-7-3-1-5-10(12)11-6-2-4-8-13(11)14/h1-8,14-15H,9H2
InChIKey = MXHVORUHWLKKMZ-UHFFFAOYSA-N
(reagent used to introduce a masked thiocarboxylic acid through thioesterification)
Alternate Name : Fm SH.
Physical Data : no reported physical data other than NMR and MS.
Solubility : soluble in Et2O, CH2Cl2, and other common organic solvents ; insoluble in water.
Form Supplied in : pale yellow oil.
Analysis of Reagent Purity : 1H and 13C NMR.
Preparative Method : not yet commercially available. FmSH can be prepared in three steps from commercially available (9H-fluoren-9-yl)methanol (FmOH) by treatment with tosyl chloride and pyridine in chloroform at rt for 6 h,1 followed by displacement of the tosylate by potassium thioacetate and 18-crown-6 in DMF at rt for 2 h, and then reduction with DIBAL-H in Et2O at –78 °C and then at 0 °C for 30 min.2 Purification requires column chromatography.
Purification : flash column chromatography on silica gel : 98:2 hexane/ethyl acetate.
Handling, Storage, and Precautions : stable under normal pressure and temperature in the absence of air. Unpleasant odor. Store in a cool dry place under an inert atmosphere. Wash thoroughly after use and remove any contaminated clothing. The toxicological properties have not been studied.

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Characterisation of a GroEL Single-Ring Mutant that Supports Growth of Escherichia coli and Has GroES-Dependent ATPase Activity

Binding and folding of substrate proteins by the molecular chaperone GroEL alternates between its two seven-membered rings in an ATP-regulated manner. The association of ATP and GroES to a polypeptide-bound ring of GroEL encapsulates the folding proteins in the central cavity of that ring (cis ring) and allows it to fold in a protected environment where the risk of aggregation is reduced. ATP hydrolysis in the cis ring changes the potentials within the system such that ATP binding to the opposite (trans) ring triggers the release of all ligands from the cis ring of GroEL through a complex network of allosteric communication between the rings. Inter-ring allosteric communication thus appears indispensable for the function of GroEL, and an engineered single-ring version (SR1) cannot substitute for GroEL in vivo. We describe here the isolation and characterisation of an active single-ring form of the GroEL protein (SR-A92T), which has an exceptionally low ATPase activity that is strongly stimulated by the addition of GroES. Dissection of the kinetic pathway of the ATP-induced structural changes in this active single ring can be explained by the fact that the mutation effectively blocks progression through the full allosteric pathway of the GroEL reaction cycle, thus trapping an early allosteric intermediate. Addition of GroES is able to overcome this block by binding this intermediate and pulling the allosteric pathway to completion via mass action, explaining how bacterial cells expressing this protein as their only chaperonin are viable.

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