Lipases: industrial biocatalysts for production of pharma intermediates and fine chemicals

Bhalchandra K Vaidy, and Sandeep Bijamwar in this article describes applications of lipases in pharma and fine chemical industry

The past decade has witnessed a heightened interest in exploring potential of enzymes for industrial organic synthesis. Chemically enzymes are proteins and functionally they are catalysts of biological systems (biocatalysts). Being catalysts, enzymes accelerate the rate of reaction by decreasing the energy of activation.

The high selectivity and specificity of enzymes make them valuable catalysts especially for synthesis of pharmaceuticals and fine chemicals, where the demand for enantiomerically pure molecules is continuously increasing [1].

Advantages of enzymes:

• Efficiency: Enzymes are far more efficient than chemical catalysts. The initial reaction rates of enzymatic (biocatalytic) transformations are roughly 1010 to 1020 times higher than that of chemo-catalysed reactions.
• Selectivity: Enzymes exhibit exceptionally high chiral (enantio-) and positional (regio-) selectivities. Thus, the tedious blocking-deblocking steps which are commonly required for asymmetric chemo-catalytic reactions are not required in biocatalytic transformations.
• Specificity: Enzymes are specific for certain chemical compounds (substrate specificity); which avoids side reactions and formation of unwanted by-products.
• Work in mild reaction conditions: Enzyme-catalysed reactions are generally carried out under mild conditions (of pH, temperature, pressure etc.) that mitigate common problems like isomerisation, racemisation or epimerisation of the product.
• Green catalysts: Enzymes are regarded as ‘green catalysts.’ They are completely biodegradable and therefore do not cause environmental pollution. Moreover, enzymatic processes are less hazardous, less polluting and consume less energy than conventional chemo-catalytic processes, especially those which use heavy-metal catalysts.

Classification of enzymes

Enzymes catalyse enormous range of reactions. They are increasingly found to transform almost any reaction of organic chemistry. According to the report of the first Enzyme Commission in 1961, enzymes are classified into six classes depending upon the type of reaction they catalyse [1]. The six classes of enzyme and corresponding type of reactions are summarised in Table 1.

Among the six classes of enzymes, hydrolases have a major share in industrial biotransformations particularly in resolution of racemic compounds and in asymmetric synthesis of enantiopure chiral compounds. Hydrolases are relatively stable enzymes and their catalysis do not require co-factor. One of the most extensively utilised enzymes of hydrolase class is lipase.

Lipases (triacylglycerol ester hydrolase, EC 3.1.1.3) are important enzymes in biological systems, where they catalyze the hydrolysis of triacylglycerol to glycerol and fatty acids. Besides their natural substrates, lipases are capable of catalysing a wide range of non-natural chemical compounds.

Depending on the nature of substrate and reaction conditions, lipases catalyze a wide range of enantio- and regio-selective reactions such as hydrolysis, esterifications, transesterifications, interesterification, aminolysis and ammoniolysis (Fig. 2). Due to their catalytic versatility, lipases have emerged as a unique industrial biocatalyst in pharmaceutical, fine chemical, food and flavouring and recently in cosmetics and perfumery industries [2].

Lipases are ubiquitous in nature and are produced by several plants, higher animals, and microorganisms. Microorganisms have shorter life-span, are easy to cultivate by fermentation and easy to manipulate genetically. Hence, most of commercial lipases are from microbial sources.

We at ‘Advanced Enzymes’ manufacture and export enzymes to the various applications for last 50 years. Our lipases are robust biocatalysts useful for industrial organic syntheses of pharmaceutical building blocks and fine chemicals. Our lipases are available in soluble and immobilised preparations. The immobilised lipases are support-bound and therefore can be recovered from the reaction mixture and can be reused for repetitive biotransformation cycles.

Lipases for pharma and fine chemical industry

The role of chirality in efficacy and safety of drugs has been thoroughly identified and implicated globally by pharma companies as well as concerned regulatory agencies. As a consequence, the production of single enantiomers of active pharmaceutical intermediates (APIs) has become increasingly important in pharma industries.

Besides pharma, the ‘chirality’ is receiving attention particularly in agrochemical, perfumery, flavour and dye industries [3]. Being stereo-selective, lipases play a significant role in production of enantiopure intermediates. Representative examples of APIs and fine chemicals which are synthesised by lipase catalysed biotransformations are listed in Table 2.

Conclusion

Enzymes (biocatalysts) are increasingly used in industrial organic synthesis. Lipases are eco-friendly, stereo-selective biocatalysts. They exhibit broad substrate specificity and catalytic versatility.

Moreover, lipase catalysed biotransformations are simple, do not require co-factor and are easy to scale-up. As a result, lipases have emerged as important industrial biocatalysts especially for production of enantiopure drug intermediates and fine chemicals.

The current trends of industrial manufacturing viz. ‘green synthesis’ and ‘sustainable development’ suggest that the commercial utilisation of lipases in pharma and fine chemical industries will continue to expand in years to come.

Furthermore, the recent technological developments in large-scale DNA sequencing, protein expression systems and enzyme engineering methods will foster the industrial utilisation of lipases, and also other enzymes by in large.

References:

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8. Ghanem, A. Trends in lipase-catalyzed asymmetric access to enantiomerically pure/enriched compounds. Tetrahedron, 63 (2007) 1721-1754.