Esterification of N-benzyloxycarbonyldipeptides in ethanol-water with immobilized papain |
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Authors: | Kawashiro K Ishizaki H Sugiyama S Hayashi H |
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Institution: | Department of Chemical Science and Technology, Faculty of Engineering, The University of Tokushima, Minamijosanjima Tokushima 770, Japan. |
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Abstract: | The esterification of some N-benzyloxycarbonyl (Z)-dipeptides in ethanol-containing water was investigated using papain as a catalyst. The esterification took place in ethanol containing a samll amount of water (2% v/v, pH 9) with free papain at room temperature. The yield (after 24 h) of the ethyl ester was in the range of 25% to 50%. Any peptide bond cleavage of the substrates was not observed during esterification, indicating that the unfavorable amidase activity of papain was well depressed under these conditions. However, dipeptides having a D-amino amino acid (Z-valyl-D-alanine) or a bulky amino acid (Z-valylvaline) at the C-terminal position could not be esterified. It was found that the immobilization of papain on Amberlite XAD-8 increased the yield of the ester significantly as compared with free papain. In the esterification of Z-valylalanine using immobilized papain, the optimum water content, pH of an added buffer, and temperature were found to be 2% (v/v), 9, and 40 degrees C, respectively. The water content affected the yield of the product ester significantly.(c) 1993 John Wiley & Sons, Inc. |
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Keywords: | Papain immobilized papain enzymatic esterification dipeptide ester esterase activity amidase activity |
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