Reductive carboxymethylation

Desalt by gel filtration on Pharmacia NAP-5 columns into 0.1 M N-ethylmorpholine. Load the protein solution in 500-/rl volume using the 0.1 M N-ethylmorpholine to dilute the reduction/carboxymethylation buffer as necessary. Collect the next 700 fA of eluate containing the desalted protein. 

Recent progress of basic and application studies in chitin chemistry was reviewed by Kurita (2001) with emphasis on the controlled modification reactions for the preparation of chitin derivatives. The reactions discussed include hydrolysis of main chain, deacetylation, acylation, M-phthaloylation, tosylation, alkylation, Schiff base formation, reductive alkylation, 0-carboxymethylation, N-carboxyalkylation, silylation, and graft copolymerization. For conducting modification reactions in a facile and controlled manner, some soluble chitin derivatives are convenient. Among soluble precursors, N-phthaloyl chitosan is particularly useful and made possible a series of regioselective and quantitative substitutions that was otherwise difficult. One of the important achievements based on this organosoluble precursor is the synthesis of nonnatural branched polysaccharides that have sugar branches at a specific site of the linear chitin or chitosan backbone [89]. 

StadtmanTC, Davis JN. 1991. Glycine reductase protein C. Properties and characterization of its role in the reductive cleavage of Se-carboxymethyl-selenoprotein A. J Biol Chem 266 22147-53. 

Photolytic. The UV photolysis (7, = 300 nm) of bifenox in various solvents was studied by Ruzo et al. (1980). In water, 2,4-dichloro-3 -(carboxymethyl)-4 -hydroxydiphenyl ether and 2,4-di-chloro-3 -(carboxymethyl)-4 -aminodiphenyl ether were identifled. In cyclohexane, 2,4-dichloro-4 -nitrodiphenyl ether and methyl formate were the major products. In methanol, a dichloro-methoxy phenol was identified. Photodegradation occurred via reductive dechlorination, de-carboxymethylation, nitro group reduction, and cleavage of the ether linkage (Ruzo et al., 1980). 

Scanu, A. M., The effect of reduction and carboxymethylation on the circular dichroic spectra of pure polypeptide classes of serum high density lipoproteins. BwMm. Biophys. Acta 200, 570-572 (1970). 

Ring opening of phthalanes 614 to form the bis-lithiated species 615 via reductive lithiation, followed by treatment with DMF furnishes anomeric 3-hydroxy-4-arylisochromans 616. The mixture of anomers obtained can be converted to a -3-carboxymethyl-4-aryl isochromans 617 using Mukaiyama s procedure (Scheme 132) <2001TL9293>. Similar bis-lithiated species can react with (—)-menthone, with the subsequent dehydration leading to C(3)-spiro-cyclic isochromans <2004S 1115>. 

That the N-terminal methionine is exposed to the solvent was also concluded from studies directed toward the reduction and alkylation of the disulfides of rhGH. The conditions that were found to be optimal for the derivatization of the four sulfhydryls of rhGH resulted in the production of a side reaction when the procedure was applied to the methionyl analog. This side product was identified as containing carboxymethyl-S-methionine at the amino terminal residue. 

The acetylation of morphine and of codeine by aspirin202 and the enzymatic hydrolysis of heroin203 and the reduction of codeinone204 have been studied. Dihydronorcodeine and dihydromorphine have been isolated from urine as metabolites of dihydrocodeine.205 Patents have been published covering the preparation of -(cyclopropylmethyOnormorphine,206 the conversion of thebaine into codeinone,207 and the preparation of nalorphine 6-sulphate.208 Salts of codeine and ethylmorphine with 5-carboxymethyl-2-thio-l,3-thiazan-4-one have been prepared.209 The circular dichroism210,211 and fluorescence characteristics212 of morphine and related bases have been studied. 

Application and Principle This assay is based on the enzymatic hydrolysis of the interior (3-1,4-glucosidic bonds of a defined carboxymethyl cellulose substrate at pH 4.5 and at 40°. The corresponding reduction in substrate viscosity is determined with a calibrated viscometer. 

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