Abstract
Lipases are among the most utilized enzymes in biocatalysis. In many instances, the main reason for their use is their high specificity or selectivity. However, when full modification of a multifunctional and heterogeneous substrate is pursued, enzyme selectivity and specificity become a problem. This is the case of hydrolysis of oils and fats to produce free fatty acids or their alcoholysis to produce biodiesel, which can be considered cascade reactions. In these cases, to the original heterogeneity of the substrate, the presence of intermediate products, such as diglycerides or monoglycerides, can be an additional drawback. Using these heterogeneous substrates, enzyme specificity can promote that some substrates (initial substrates or intermediate products) may not be recognized as such (in the worst case scenario they may be acting as inhibitors) by the enzyme, causing yields and reaction rates to drop. To solve this situation, a mixture of lipases with different specificity, selectivity and differently affected by the reaction conditions can offer much better results than the use of a single lipase exhibiting a very high initial activity or even the best global reaction course. This mixture of lipases from different sources has been called “combilipases” and is becoming increasingly popular. They include the use of liquid lipase formulations or immobilized lipases. In some instances, the lipases have been coimmobilized. Some discussion is offered regarding the problems that this coimmobilization may give rise to, and some strategies to solve some of these problems are proposed. The use of combilipases in the future may be extended to other processes and enzymes.
Highlights
The synergy between immobilized lipase from R. oryzae and Novozym 435 in biodiesel production was showed in another research, increasing the yield by 30% compared to the results obtained using the immobilized lipase from R. oryzae [405]
This review shows how combilipases may have a great potential in the development of modifications of heterogeneous substrates
The improvements in free fatty acids or biodiesel production have been clearly illustrated because it is unlikely that a single lipase can modify all the different triglycerides in an oil, and less considering the partial glycerides produced during the reaction
Summary
Enzymes are very precise performing their catalytic activity, it is true that in many cases it is necessary to increase their activity versus industrially relevant substrates (in some instances far from the physiological ones) and/or stability for making them compatible with operational conditions, mainly at the industrial level [26]. For this aim, there are several accepted strategies. This was attached to just one of the Ser located in the active centers, enabling a fully directed chemical modification of the plurizyme, and the artificial semimetal plurizyme was used in a cascade reaction involving both, the enzyme active center and the metal catalysts [89]
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