Enhancement of stability of a lipase by subjecting to three phase partitioning (TPP): structures of native and TPP-treated lipase from Thermomyces lanuginosa

Improving the Thermostability of Thermomyces lanuginosus Lipase by Restricting the Flexibility of N-Terminus and C-Terminus Simultaneously via the 25-Loop Substitutions

(1) Lipases are catalysts widely applied in industrial fields. To sustain the harsh treatments in industries, optimizing lipase activities and thermal stability is necessary to reduce production loss. (2) The thermostability of Thermomyces lanuginosus lipase (TLL) was evaluated via B-factor analysis and consensus-sequence substitutions. Five single-point variants (K24S, D27N, D27R, P29S, and A30P) with improved thermostability were constructed via site-directed mutagenesis. (3) The optimal reaction temperatures of all the five variants displayed 5 °C improvement compared with TLL. Four variants, except D27N, showed enhanced residual activities at 80 °C. The melting temperatures of three variants (D27R, P29S, and A30P) were significantly increased. The molecular dynamics simulations indicated that the 25-loop (residues 24-30) in the N-terminus of the five variants generated more hydrogen bonds with surrounding amino acids; hydrogen bond pair D254-I255 preserved in the C-terminus of the variants also contributes to the improved thermostability. Furthermore, the newly formed salt-bridge interaction (R27…E56) in D27R was identified as a crucial determinant for thermostability. (4) Our study discovered that substituting residues from the 25-loop will enhance the stability of the N-terminus and C-terminus simultaneously, restrict the most flexible regions of TLL, and result in improved thermostability.

Modulation of the Catalytic Properties of Immobilized Recombinant Lipase from Thermomyces lanuginosus in the Reaction of Esterification by the Selection of an Adsorbent

Abstract

Biocatalysts with lipase activity (BLAs) were prepared by adsorptive immobilization of recombinant lipase (rPichia/lip) from thermophilic microscopic fungi Thermomyces lanuginosus produced by a genetically engineered strain of methylotrophic yeast Komagataella phafii (Pichia pastoris). Supports with different physicochemical properties were used as adsorbents: mesoporous hydrophilic silica (SiO2) and macroporous hydrophobic carbon aerogel (MCA). The enzymatic activity, substrate specificity and operational stability of BLAs were studied in the esterification of saturated fatty acids with aliphatic alcohols differing in the number of carbon atoms in the molecule from 2 to 18. Matrices of relative activities were compiled for more than 60 pairs of substrates, an acid and an alcohol, by comparing the reaction rates of the esterification under identical conditions, which allowed us to reveal differences in the specificity of adsorbed lipase depending on the chemical nature of the support. It was found that for both types of biocatalysts, rPichia/lip on SiO2 (PLSi) and rPichia/lip on MCA (PLC), the maximum reaction rate was observed under esterification of heptanoic acid (C7) with butyl alcohol (C4). Under the same conditions of the synthesis of esters (20 ± 2°C, 1 bar, a mixture of hexane and diethyl ether as an organic solvent), including the synthesis of butylheptanoate, rPichia/lip adsorbed on silica showed an order of magnitude lower activity than lipase adsorbed on carbon aerogel. The catalytic constants, equal to 3.7 s–1 and 1.1 × 102 s–1, respectively, differed by 30 times. It was found that esters of short chain fatty acids C4–C7 and ethyl alcohol C2 were synthesized 2–3 times faster using the hydrophobic PLC type than using the hydrophilic PLSi type of BLAs. At the same time, esters of high-molecular-weight acids С9, C10, С18 and alcohols С8–С16 with pronounced hydrophobicity were synthesized 1.5–2 times faster using of PLSi type BLAs. The operational stability of the biocatalysts was quite high: the prepared BLAs retained 82–99% of their initial activity after more than 30 reaction cycles, while the duration of each cycle to reach an acid conversion above 85% was several hours (4–6 h).

Perspectives on the Role of Enzymatic Biocatalysis for the Degradation of Plastic PET

Plastics are highly durable and widely used materials. Current methodologies of plastic degradation, elimination, and recycling are flawed. In recent years, biodegradation (the usage of microorganisms for material recycling) has grown as a valid alternative to previously used methods. The evolution of bioengineering techniques and the discovery of novel microorganisms and enzymes with degradation ability have been key. One of the most produced plastics is PET, a long chain polymer of terephthalic acid (TPA) and ethylene glycol (EG) repeating monomers. Many enzymes with PET degradation activity have been discovered, characterized, and engineered in the last few years. However, classification and integrated knowledge of these enzymes are not trivial. Therefore, in this work we present a summary of currently known PET degrading enzymes, focusing on their structural and activity characteristics, and summarizing engineering efforts to improve activity. Although several high potential enzymes have been discovered, further efforts to improve activity and thermal stability are necessary.

Stability comparison of four lipases and catalytic mechanism during the synthesis of 1,3-di-oleic-2-medium chain triacylglycerols in a trace water-in-oil system: Experimental analyses and computational simulations

In the present study, a kind of structured lipids, namely 1,3-di-oleic-2-medium chain (OMO) triacylglycerols, were synthesized through lipase-catalyzed reactions using coconut oil and rapeseed acid as materials in a trace water-in-oil system. Experimental analysis and computational simulations were undertaken to compare the stability of four lipases including Lipozyme RMIM, Lipozyme TLIM, Novozym 435, and Aspergillus oryzae immobilized lipase (AOIM), and illustrate catalytic mechanism of Novozym 435 during the synthesis of OMO. Fourier transform infrared and molecular dynamics simulation results demonstrated that a decrease in ordered structure (α-helix and β-sheet) led to a reduction in enzyme activity. Compared with Lipozyme RMIM and Novozym 435, Lipozyme TLIM and AOIM exhibited better stability due to a short-chain lid in TLIM, which covers activity sites, and hydrogen bonds formed between activity center of AOIM and water. Among four lipases, AOIM exhibited best catalytic performance: a OMO yield of 30.7% at 3 hr and a good stability of long term (48 hr). Density functional theory results demonstrated that specifically, during the synthesis of OMO triacylglycerol, the addition of Novozym 435 (derived from Candida antarctica lipase B, CALB) substantially lowered reaction barriers (64.4 KJ/mol with CALB vs. 332.7 KJ/mol with no lipase), aiding in the generation of OMO because of the formations of transitional tetrahedral intermediates. A trace water-in-oil system was a green and efficient alternative for lipase-catalyzed production of OMO, and this study provided crucial insights into the stability/instability and catalytic mechanisms of lipase in the synthesis of structured lipids. PRACTICAL APPLICATIONS: We compared the stability of Lipozyme RMIM, Lipozyme 435, Lipozyme TLIM, and AOIM during the synthesis of the OMO triacylglycerols in a trace water-in-oil system, where exhibited a high catalytic activity of lipase in water-oil interface. AOIM had the highest stability and showed the best catalytic performance due to the formation of hydrogen bonds. Besides, for the first time, the transition tetrahedral structure was revealed in the enzymatic synthesis of medium- and long-chain triacylglycerols. This study provides a rational approach to compare lipase stability and a possible hint to choose appropriate enzyme in a specific catalytic condition.

Lipases: An Overview

Lipases are ubiquitous enzymes, widespread in nature. They were first isolated from bacteria in the early nineteenth century, and the associated research continuously increased due to the characteristics of these enzymes. This chapter reviews the main sources, structural properties, and industrial applications of these highly studied enzymes.

Three phase partitioning and spectroscopic characterization of bioactive constituent from halophilic Bacillus subtilis EMB M15

In the present study, a halophilic Bacillus subtilis subsp. spizizenii (NCBI GenBank accession number KX109607) was isolated from the Sambhar Salt Lake, Rajasthan India. This organism exhibited significance antibacterial and antifungal activity against Proteus vulgaris, Bacillus subtilis, Aspergillus niger, Rhizopus oligosporus and Penicillium chrysogenum respectively. The bioactive constituent responsible for it was extracted by three phase partitioning and purified by column chromatography. The purified compound was further characterized by FTIR-ATR, NMR and Mass spectrometry. The mass spectra show a molecular ion of m/z 301.14. The compound has very high antimicrobial activity showing 35mm zone of inhibition against Bacillus subtilis.