Modification of Reactivity

The selective modification of reactive side chains within proteins with compounds containing NMR-sensitive isotopes offers an alternative route to the labeling of proteins. The chemical modification of side chains with reagents labeled with NMR-sensitive isotopes may permit detailed structural and dynamic questions to be addressed, although perturbations of the system caused by the labeling may be of concern in cases where the chemical identity... 

The organic chemistry of aromatic and heteroaromatic compounds is particularly well-understood. The effects of substituents and ring heteroatoms on the rates and sites of attack by nucleophiles and electrophiles are both predictable and capable of rationalisation. What can the co-ordination chemist offer to an area as well-characterised as this Perhaps because the organic chemistry of these systems is so well-behaved, the potential for modification of reactivity by co-ordination is great. 

Other methods of stabilization include chemical or carbohydrate modification of enzymes. Modifications of reactive groups on proteins without insolubilization has been used to enhance stability in solution. Grafting of polysaccharides or synthetic polymers, alkalation, acetylation and amino acid modification have all been reported (5)... 

It is well known that the redox responsiveness in proteins may be conferred by S-NO (nitrosylation), S-OH (sulfenic acid), S-S (intramolecular disulfide), and S-SR (mixed disulfide or S-thiolation), all potential reversible modifications of reactive cysteines (Figure... 

J. P. Collman, T. Kodadek, S. A. Raybuck, B. Meunier, Oxygenation of hydrocarbons by cytochrome P-450 model compounds Modification of reactivity by axial ligands, Proc. Hail. Acad. Sci. USA 80 (1983) 7039. 

Infrared and ultraviolet spectroscopies, introduced in the chemistry of natural products about three decades later, provided the first evidence to support this idea [8, 9]. The discovery of similar modification of reactivity of amino and keto groups across a nine-membered ring of vomicine [10], a strychnine congener [11], pointed to the generality of such transannular interactions in medium-size rings. This then became the topic of systematic and extensive investigations by Leonard and coworkers [12]. 

Adekunle, K., Aakesson, D. and Skrifvars, M. (2008) Synthetic modification of reactive soybean oils for use as biobased thermoset resins in stmctural natural fiber composites. Polymer Preprints (American Chemical Society, Division of Polymer Chemistry), 49(1), 279-280. 

Compared to classical statistical copolymerizations, the occurrence of transfer could have an effect in terms of activity, selectivity, and comonomer contents (modification of reactivity ratios). 

L. Garcfa-Rio, J.C. Mejuto, and M. Perez-Lorenzo, Modification of reactivity by changing microemnlsion composition. Basic hydrolysis of nitrophenyl acetate in AOT/isooctane/water systems, 2004, New J. Chem. 28, 988-995. 

Although most of the work on the use of phase transfer catalysis for the chemical modification of polymers was carried out in the last five years, the first report of the application of this technique to the modification of reactive polymers originated ten years ago from the laboratory of Okawara, one of the great innovators of polymer chemistry, and was concerned with the chemical modification of poly(vinyl chloride) (Ref. 10, 11). This was followed by simultaneous brief reports by Roovers (Ref. 12) and by Roeske et al. (Ref. 13) describing the use of 18-crown-6 in the reaction of carboxylates with poly(chloromethyl styrene). Our own first report (Ref.14) in this field described the use of phase transfer catalysis to control site-site interactions in the... 

In organometallic chemistry, alkenes play a fundamental role because their coordination to the metal center allows an increase or a modification of reactivity compared to classical metal-free reactions. A variety of chiral ligands... 

Post-polymerization modification of reactive polymer films provides the possibility to design complex coatings associated with intricate structure and morphology [1, 4, 97, 98]. Using a simple procedure, two or more types of chemical functionalities can be applied onto substrates that are contained in covalently grafted polymer films. Multifunctional surfaces can be fabricated by sequential click reactions or simultaneous multiple click reactions in one-pot. Click-like reactions such as thiol-based additions, activated ester coupling, and azide-alkyne cycloadditions are those most used for post-polymerization modification, because these reactions yield orthogonal reactive polymer brushes rapidly and quantitatively [17]. 

Buck ME, Breitbach AS, Belgrade SK, Blackwell HE, Lyim DM (2009) Chemical modification of reactive multilayered films fabricated from poly(2-alkenyl azlactone)s design of... 

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