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首页> 外文期刊>World Journal of Microbiology & Biotechnology >Scanning electron microscopic studies of lipase-catalysed esterificationcatalysis for the synthesis of stearoyl lactate and p-cresyl laurate
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Scanning electron microscopic studies of lipase-catalysed esterificationcatalysis for the synthesis of stearoyl lactate and p-cresyl laurate

机译：脂肪酶催化的酯化催化合成硬脂酰乳酸和月桂酸对甲酚酯的扫描电镜研究

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摘要

The state of three lipases, two from Rhizomucor miehei and one from porcine pancreas, employed in the esterification reactions leading to the preparation of food additive esters were investigated by scanning electron microscopy (SEM). The lipases employed in the synthesis of stearoyl lactic acid and p-cresyl laurate in 10 ml solvent at 40-60 degreesC in shake-flask experiments and 150 ml in non-polar solvents at 50-60 degreesC in bench-scale level experiments were compared. All three lipases, which were subjected to high temperatures and non-polar solvents for a prolonged period of incubation of 72-120 h, showed decrease in the 'compactness' when compared to unused lipase. The presence of buffer preserved the activity and compactness and the absence of the same reduced the amount of enzyme per unit area on the support. R. miehei lipase samples subjected to reaction in presence of 0.0004 ml of 0.1 M buffer/mg enzyme preparation at different pH values (4.0-9.0) showed a decrease in compactness of the enzyme on the surface which correlated to an increase in esterification activity. An increase in volume of buffer (0.0002-0.003 ml/mg enzyme preparation) in the reaction mixture at pH 7.0 showed a decrease in compactness and also a reduction in activity. The studies indicate that a compromise between pH and volume of buffer can lead to variation in the extent of adsorption, distribution and activity, enabling the achievement of maximum conversions in the esterification reactions.
机译：通过扫描电子显微镜（SEM）研究了在酯化反应中使用的三种脂肪酶的状态，两种脂肪酶来自米黑根霉（Rhizomucor miehei），另一种来自猪胰腺，用于制备食品添加剂酯。比较了摇瓶实验中在40-60°C下于10 ml溶剂中合成硬脂酰乳酸和对甲基月桂酸月桂酯的脂肪酶，在台式实验中在50-60℃下于非极性溶剂中于150 ml合成了脂肪酶。 。与未使用的脂肪酶相比，在高温和非极性溶剂中长时间孵育72-120小时的所有三种脂肪酶均显示出“致密性”降低。缓冲液的存在保留了活性和紧密度，而没有缓冲液则降低了载体上每单位面积的酶量。在0.0004 ml的0.1 M缓冲液/ mg酶制剂中，在不同的pH值（4.0-9.0）下进行反应的米江红霉脂肪酶样品显示酶在表面的紧密度降低，这与酯化活性的增加有关。 pH 7.0下反应混合物中缓冲液体积的增加（0.0002-0.003 ml / mg酶制剂）显示致密性降低，活性也降低。研究表明，pH和缓冲液体积之间的折衷可能导致吸附，分布和活性程度的变化，从而实现酯化反应的最大转化率。

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