作者:Rein V. Ulijn、Nicola Bisek、Peter J. Halling、Sabine L. Flitsch
DOI:10.1039/b211890d
日期:2003.4.14
A protease (thermolysin) was used to directly synthesise a number of dipeptides from soluble Fmoc-amino acids onto a solid support (PEGA1900) in bulk aqueous media, often in very good yields. This shift in equilibrium toward synthesis is remarkable because for soluble dipeptides in aqueous solution hydrolysis rather than synthesis is observed. Three possible reasons for the equilibrium shift were considered: (i) using a solid support makes it easy to use an excess of reagents, so mass action contributes towards synthesis; (ii) reduction in the unfavourable hydrophobic hydration of the Fmoc group within the solid support compared with the free amino acid in solution and (iii) suppression of the ionization of amino groups linked to the solid phase due to mutual electrostatic repulsion. It was found that under the conditions studied the second effect was most important.
一种蛋白酶(热溶菌素)被用于在水相中直接将可溶性Fmoc-氨基酸合成多种二肽,并将其固定在固相载体(PEGA1900)上,通常产率很高。这种向合成方向的平衡移动很显著,因为在水溶液中可溶性二肽往往发生水解而不是合成。考虑了三种可能导致平衡移动的原因:(1)使用固相载体便于使用过量试剂,质量作用有利于合成;(2)与溶液中游离氨基酸相比,固相载体中Fmoc基团的不利疏水水合作用减小;(3)由于静电相互排斥作用,与固相连接的氨基离子化受到抑制。研究发现在所研究的条件下第二种效应最为重要。