Background:levo-Menthol is an important flavoring chemical,which can be prepared by enantioselective enzymatic hydrolysis of dl-menthyl esters.A recombinant esterase(BsE)cloned from Bacillus subtilis 0554 shows excell...Background:levo-Menthol is an important flavoring chemical,which can be prepared by enantioselective enzymatic hydrolysis of dl-menthyl esters.A recombinant esterase(BsE)cloned from Bacillus subtilis 0554 shows excellent enantioselectivity to dl-menthyl acetate and has been immobilized using cross-linked enzyme aggregates.Though BsE has relatively high substrate tolerance,the conversion of dl-menthyl acetate decreased sharply with the increase of substrate loading from 1 to 3 M in mono-aqueous system,which might be due to the severe inhibition of enzyme activity at extremely high load of substrate or product.In this work,enzymatic hydrolysis of dl-menthyl acetate with an extremely high load using the immobilized CLEA-BsE was investigated in an organic-aqueous biphasic system containing surfactant to establish a promising bioprocess for large-scale production of l-menthol.Results:An efficient biphasic reaction system of pentanol-water containing sodium dodecyl sulfate(SDS)was developed for improving enantioselective hydrolysis of dl-menthyl acetate to produce l-menthol by immobilized BsE.Under the optimized reaction conditions,l-menthol was produced in>97%enantiomeric excess(ee)at a substrate load of up to 3.0 M with>40%conversion.Conclusions:All the positive features demonstrate the potential applicability of the bioprocess for the large-scale production of l-menthol.展开更多
目的探讨薄荷醇对皮肤角质层结构影响的作用机制。方法大鼠皮肤角质层样本和健康志愿者皮肤给予薄荷醇后,测定全衰减反射傅里叶变换红外光谱(ATR-FTIR)在皮肤角质层的变化,以确定皮肤角质层结构是否改变。结果在大鼠皮肤实验中,与对照...目的探讨薄荷醇对皮肤角质层结构影响的作用机制。方法大鼠皮肤角质层样本和健康志愿者皮肤给予薄荷醇后,测定全衰减反射傅里叶变换红外光谱(ATR-FTIR)在皮肤角质层的变化,以确定皮肤角质层结构是否改变。结果在大鼠皮肤实验中,与对照组和溶剂组相比,氮酮组大鼠角质层中的CH2对称振动(2 854 cm 1)发生了相对位移,角蛋白NH-C=O振动I峰(1 659 cm 1)及II峰(1 637 cm 1)发生了位移,NH-C=O振动I峰发生了裂峰;薄荷醇组大鼠角质层中CH2非对称振动(2 925 cm 1)、CH2对称振动(2 854 cm 1)发生相对位移。在人体皮肤试验中,与对照区和溶剂区相比,氮酮组CH2非对称振动(2 921.5 cm 1)和CH2对称振动(2 852.1 cm 1)发生了3～4个波长位移;薄荷醇组CH2非对称振动(2 922.7 cm 1)和CH2对称振动(2 853.8 cm 1)发生了3～4个波长位移。结论薄荷醇可能是通过改变角质层中脂质的构象,使角质层脂质双分子层的流动性增加、有序致密结构改变,降低皮肤屏障作用,从而使药物的透过性增加。展开更多
基金financial supports by the Ministry of Science and Technology,P.R.China(Nos.2011AA02A210 and 2011CB710800)the Open Fund of State Key Laboratory of Bioreactor Engineering(2060204),are gratefully acknowledged.
文摘Background:levo-Menthol is an important flavoring chemical,which can be prepared by enantioselective enzymatic hydrolysis of dl-menthyl esters.A recombinant esterase(BsE)cloned from Bacillus subtilis 0554 shows excellent enantioselectivity to dl-menthyl acetate and has been immobilized using cross-linked enzyme aggregates.Though BsE has relatively high substrate tolerance,the conversion of dl-menthyl acetate decreased sharply with the increase of substrate loading from 1 to 3 M in mono-aqueous system,which might be due to the severe inhibition of enzyme activity at extremely high load of substrate or product.In this work,enzymatic hydrolysis of dl-menthyl acetate with an extremely high load using the immobilized CLEA-BsE was investigated in an organic-aqueous biphasic system containing surfactant to establish a promising bioprocess for large-scale production of l-menthol.Results:An efficient biphasic reaction system of pentanol-water containing sodium dodecyl sulfate(SDS)was developed for improving enantioselective hydrolysis of dl-menthyl acetate to produce l-menthol by immobilized BsE.Under the optimized reaction conditions,l-menthol was produced in>97%enantiomeric excess(ee)at a substrate load of up to 3.0 M with>40%conversion.Conclusions:All the positive features demonstrate the potential applicability of the bioprocess for the large-scale production of l-menthol.
文摘目的探讨薄荷醇对皮肤角质层结构影响的作用机制。方法大鼠皮肤角质层样本和健康志愿者皮肤给予薄荷醇后,测定全衰减反射傅里叶变换红外光谱(ATR-FTIR)在皮肤角质层的变化,以确定皮肤角质层结构是否改变。结果在大鼠皮肤实验中,与对照组和溶剂组相比,氮酮组大鼠角质层中的CH2对称振动(2 854 cm 1)发生了相对位移,角蛋白NH-C=O振动I峰(1 659 cm 1)及II峰(1 637 cm 1)发生了位移,NH-C=O振动I峰发生了裂峰;薄荷醇组大鼠角质层中CH2非对称振动(2 925 cm 1)、CH2对称振动(2 854 cm 1)发生相对位移。在人体皮肤试验中,与对照区和溶剂区相比,氮酮组CH2非对称振动(2 921.5 cm 1)和CH2对称振动(2 852.1 cm 1)发生了3～4个波长位移;薄荷醇组CH2非对称振动(2 922.7 cm 1)和CH2对称振动(2 853.8 cm 1)发生了3～4个波长位移。结论薄荷醇可能是通过改变角质层中脂质的构象,使角质层脂质双分子层的流动性增加、有序致密结构改变,降低皮肤屏障作用,从而使药物的透过性增加。
