Alcohols binding

Dubey, A. K., Eryomin, Y. A., Taraschi, T. F. and Janes, N. (1996). Alcohol binding to liposomes by 2H NMR and radiolabel binding assays does partitioning describe binding Biophys. J., 70, 2307-2315. 

The metal-alcoholate mechanism is well established for allylic alcohol epoxidation in the presence of Ti and V catalysts. [41, 51, 52, 111-113], In principle, it can provide a viable pathway also for catalysis by a Re complex. In fact, allylic alcohols may add, at least formally, to either an oxo-Re or peroxo-Re moiety (e.g. of 5a or 5b) in a process which is referred to as metal-alcoholate binding this mechanism gives rise to metal-alcoholate intermediates. We identified four intermediates of alcohol addition to di(peroxo) complexes two resulting transition states, S-8 and S-9b, are shown in Figure 11. All metal-alcoholate intermediates he significantly higher in energy (by 10-22 kcal/mol) than 5b + propenol, except the... 

The empirical observation that (—)-sparteine 55 is necessary for catalysis implicates a base-promoted pathway in the mechanism. In the first step, a palladium alk-oxide is formed after alcohol binding, followed by p-hydride elimination of the alkoxide to yield a ketone product. On the basis of a kinetic study of the enantio-selective oxidation of 1-phenylethanol, it was revealed that (—)-sparteine plays a dual role in the oxidative kinetic resolution of alcohols, as a ligand on palladium and an exogeneous base " ... 

Allylic alcohols can also be epoxidized with methyltrioxorhenium (MTO). However, in contrast to the early transition metal catalysts, metal-alcoholate binding does not appear to be operative, but rather straightforward hydrogen bonding, as demonstrated by the epoxidation of geraniol (20)... 

Edrophonium Alcohol, binds briefly to active site of acetylcholinesterase (AChE) and prevents access of acetylcholine (ACh) Amplifies all actions of ACh increases parasympathetic activity and somatic neuromuscular transmission Diagnosis and acute treatment of myasthenia gravis Parenteral quaternary amine does not enter CNS Toxicity Parasympathomimetic excess Interactions Additive with parasympathomimetics... 

Both these mechanisms propose that the alcohol substrate combines with the unprotonated form of the enzyme-NAD+ complex. Kvassman and Pettersson have proposed an alternative mechanism in which alcohol binding to the binary complex requires the presence of a neutral... 

A consequence of the direction of the hydrogen bonding is that the alcohol binds preferentially to (he basic form (B) of the catalyst, whereas the aldehyde binds preferentially to the acidic form (BH+). The pKa of B is lowered in the E-NAD1 -RCH2OH tertiary complex and raised in the E-NADH-RCHO complex. 

The allylic alcohol binds to the remaining axial coordination site, where stereochemical and stcrcoelectronic effects dictate the conformation shown in Figure 6A.9 [6]. The structural model of catalyst, oxidant, and substrate shown in Figure 6A.9 illustrates a detailed version of the formalized rule presented in Figure 6A. 1. Ideally, all observed stereochemistry of epoxy alcohol and kinetic resolution products can be rationalized according to the compatibility of their binding with the stereochemistry and stereoelectronic requirements imposed by this site [6]. A... 

Hydroxylation of tertiary carbon atoms (6, 440 7, 271-273). The hydrogen succinates of alcohols bind strongly to silica gel. Unactivated tertiary C—H bonds in these bound substrates are oxidized efficiently with a solution of O3 in Ereon 11. This method is preferable to the oxygenation of acetates adsorbed on silica gel. Examples ... 

Williams, T. M., and Borghoff, S. J. (2001). Characterization of iert-butyl alcohol binding to alpha2u-globulin in F-344 rats. Toxicol Sci 62, 228-235. 

As defined above, the macroscopic rate constant kcat/f M reflects all steps from alcohol binding up to and including the first irreversible step, and is probed by competitive isotope effect measurements (cf Eq. (10.4) in Section 10.2). As pointed out by Northrop, the observed isotope effect on kcat/Ku can be formulated in terms of the intrinsic isotope effect on the chemical step ((kH/kT)int)j and the commitment to catalysis Ch [60]. Ch accounts for the relative importance of chemical and nonchemical steps that contribute to k t/Ku when H is the isotope under study a similar expression results for D/T isotope effects involving Cd. Under all conditions, Cd < CH/(kH/kD)int, making D/T KIEs less susceptible to kinetic complexity than H/T KIEs. 

A direct demonstration of binding of alcohol to LADH in the absence of coenzyme has been made (253) by utilizing the spectroscopic changes and protein fluorescence quenching that occur when the chromophoric substrate hydroxymethyl ferrocene binds. It was not definitively established, however, that the alcohol binds in the substrate binding pocket. 

It is proposed in the mechanism that alcohol binds to zinc as the negatively charged alcoholate ion and displaces the hydroxyl ion. The formation of alcoholate ion is mediated here by the hydroxyl ion bound to zinc. This base can combine with the proton of the hydroxyl group of... 

KRUSE, S.W., ZHAO, R., SMITH, D.P., JONES, D.N.M., Structure of a specific alcohol-binding site defined by the odorant binding protein lush from Drosophila melanogaster. Nature Str. Biol, 2003,10, 694-700. 

An alternative hypothesis is that the amino alcohol induces enantioselectivity by binding to the active site and changing its shape. An X-ray structure shows that Tris buffer (an amino alcohol) binds to the hydrophobic patch in the active site of carbonic anhydrase [58]. Similar binding of other amino alcohols could restrict the orientation of p-chlorostyrene in the active site. This second hypothesis does not explain why Femandez-Gacio et al. found no effect of buffer on enantioselectivity. 

I. J. Goldstein, B. A. Lewis, and F. Smith, The alcohol-binding capacity and mutarotation of the so-called dialdehydes obtained by periodate oxidation of sugar glycosides, Chem. Ind. (London), (1958) 595-596. 

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