Gayot S, Santarelli X, Coulon D
ESTBB, Université Victor Ségalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
J Biotechnol. 2003 Feb 27;101(1):29-36. doi: 10.1016/s0168-1656(02)00286-9.
The enzymatic acylation of a flavonoid (naringin) was investigated in this work. This atypic substrate for a lipase was esterified very selectively by the immobilized Candida antarctica lipase: a single product was synthesized and was assumed to be the 6-O-palmitate naringin ester acylated on the glucose moiety. As lipase-catalyzed esterification reactions in organic media are greatly influenced by the water content, the effect of the initial hydration level of the reaction medium components was pointed out for naringin palmitate synthesis. 2-Methyl 2-butanol (solvent) and naringin (acyl acceptor) provided high amounts of water and when dried increased the conversion yield by 63% and the specific activity by 60%. On the contrary, the enzyme must not be dried because water is essential for the three-dimensional structure of the protein and, if absent, results in a 67% loss of activity. As water was produced in parallel to ester synthesis, the equilibrium of the reaction might be shifted by its removal. When the reaction was carried out with 100 g l(-1) molecular sieves 4A added after 24 h of reaction, a conversion yield of 43% was reached after 55 h reaction.
本研究对类黄酮（柚皮苷）的酶促酰化反应进行了探究。这种脂肪酶的非典型底物被固定化的南极假丝酵母脂肪酶非常有选择性地酯化：合成了单一产物，推测其为在葡萄糖部分酰化的6-O-棕榈酸柚皮苷酯。由于有机介质中脂肪酶催化的酯化反应受水含量的影响很大，因此指出了反应介质组分的初始水合水平对棕榈酸柚皮苷合成的影响。2-甲基-2-丁醇（溶剂）和柚皮苷（酰基受体）含有大量水分，干燥后转化率提高了63%，比活性提高了60%。相反，酶不能干燥，因为水对蛋白质的三维结构至关重要，缺水会导致67%的活性损失。由于在酯合成的同时会产生水，反应平衡可能会因水的去除而发生移动。当在反应24小时后加入100 g l(-1) 4A分子筛进行反应时，反应55小时后转化率达到43%。
