Methanolysis of ethyl esters of N-acetyl amino acids catalyzed by cyclosophoraoses isolated from Rhizobium meliloti

Methanolysis of four ethyl esters, N-acetyl-l-phenylalanine ethyl ester, N-acetyl-l-tyrosine ethyl ester, N-acetyl-l-tryptophan ethyl ester, and ethyl phenylacetate was catalyzed by a mixture of microbial cyclooligosaccharides termed cyclosophoraoses isolated from Rhizobium meliloti. Cyclosophoraoses [cyclic-(1→2)-β-d-glucans, collectively ‘Cys’] are a mixture of large-ring molecules consisting of various numbers of glucose residues (17–27) linked by β-(1→2)-glycosidic bonds. Cys as a catalytic carbohydrate enhanced the methanolysis about 233-fold for N-acetyl-l-tyrosine ethyl ester in comparison with a control. The effect of dry organic solvents on the methanolysis of N-acetyl-l-tyrosine ethyl ester was investigated by high-performance liquid chromatography (HPLC), and it was found that the rate enhancement correlated closely with the hydrophobicity of the solvent.

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