Comparative Proteomic Analysis Reveals the Effect Mechanisms of Glucose on the Biomass and Phenolic Glycoside Esters Synthesis Activity of Candida Parapsilosis ACCC 20221 Whole-Cell Catalyst

A new Candida parapsilosis ACCC 20221 (C. parapsilosis ACCC 20221) whole-cell catalyst with a high phenolic glycoside esters synthesis activity and large biomass was obtained after culture with glucose. The possible mechanisms were revealed by using comparative proteomics. It found the expression of proteins involved in post-translational modification, protein turnover, and chaperone, and RNA processing and modification was upregulated, which ensured the metabolic balance and accurate translation, correct folding, and post-translational modification of proteins, thus enhancing the production of lipases in C. parapsilosis ACCC 20221 cultured with glucose. Moreover, the glycolysis pathway, tricarboxylic acid cycle, and fatty acids synthesis were enhanced, while the β-oxidation of fatty acids was weakened in C. parapsilosis ACCC 20221 cells cultured with glucose, which led to an increase in energy generation and cell membrane synthesis; thus, large biomass was obtained. In addition, CCE40476.1 and CAC86400.1, which were likely to exert arbutin esters synthesis activity in C. parapsilosis ACCC 20221, were screened, and it was found that vinyl propionate could easily enter the catalytic pocket of CCE40476.1 and form hydrogen bonding interactions with Leu191 and Ser266.

Structural Basis by Which the N-Terminal Polypeptide Segment of Rhizopus chinensis Lipase Regulates Its Substrate Binding Affinity

Members of an important group of industrial enzymes, Rhizopus lipases, exhibit valuable hydrolytic features that underlie their biological functions. Particularly important is their N-terminal polypeptide segment (NTPS), which is required for secretion and proper folding but is removed in the process of enzyme maturation. A second common feature of this class of lipases is the α-helical "lid", which regulates the accessibility of the substrate to the enzyme active site. Some Rhizopus lipases also exhibit "interfacial activation" by micelle and/or aggregate surfaces. While it has long been recognized that the NTPS is critical for function, its dynamic features have frustrated efforts to characterize its structure by X-ray crystallography. Here, we combine nuclear magnetic resonance spectroscopy and X-ray crystallography to determine the structure and dynamics of Rhizopus chinensis lipase (RCL) with its 27-residue NTPS prosequence (r27RCL). Both r27RCL and the truncated mature form of RCL (mRCL) exhibit biphasic interfacial activation kinetics with p-nitrophenyl butyrate (pNPB). r27RCL exhibits a substrate binding affinity significantly lower than that of mRCL due to stabilization of the closed lid conformation by the NTPS. In contrast to previous predictions, the NTPS does not enhance lipase activity by increasing surface hydrophobicity but rather inhibits activity by forming conserved interactions with both the closed lid and the core protein structure. Single-site mutations and kinetic studies were used to confirm that the NTPS serves as internal competitive inhibitor and to develop a model of the associated process of interfacial activation. These structure-function studies provide the basis for engineering RCL lipases with enhanced catalytic activities.

Biodiesel production from crude jatropha oil catalyzed by immobilized lipase/acyltransferase from Candida parapsilosis in aqueous medium

The lipase/acyltransferase from Candida parapsilosis (CpLIP2) immobilized on two synthetic resins (Accurel MP 1000 and Lewatit VP OC 1600) was used as catalyst for the production of biodiesel (fatty acid methyl esters, FAME) by transesterification of jatropha oil with methanol, in a lipid/aqueous system. The oil was dispersed in a buffer solution (pH 6.5) containing methanol in excess (2M in the biphasic system; molar ratio methanol/acyl chains 2:1). Transesterification was carried out at 30°C, under magnetic stirring, using 10% (w/w) of immobilized enzyme in relation to oil. The maximum FAME yields were attained after 8h reaction time: 80.5% and 93.8%, when CpLIP2 immobilized on Accurel MP 1000 or on Lewatit VP OC 1600 were used, respectively. CpLIP2 on both Accurel MP 1000 and Lewatit VP OC 1600 showed high operational stability along 5 consecutive 8h batches.

Synthesis of structured triacylglycerols enriched in n-3 fatty acids by immobilized microbial lipase

The search for new biocatalysts has aroused great interest due to the variety of micro-organisms and their role as enzyme producers. Native lipases from Aspergillus niger and Rhizopus javanicus were used to enrich the n-3 long-chain polyunsaturated fatty acids content in the triacylglycerols of soybean oil by acidolysis with free fatty acids from sardine oil in solvent-free media. For the immobilization process, the best lipase/support ratios were 1:3 (w/w) for Aspergillus niger lipase and 1:5 (w/w) for Rhizopus javanicus lipase using Amberlite MB-1. Both lipases maintained constant activity for 6 months at 4°C. Reaction time, sardine-free fatty acids:soybean oil mole ratio and initial water content of the lipase were investigated to determine their effects on n-3 long-chain polyunsaturated fatty acids incorporation into soybean oil. Structured triacylglycerols with 11.7 and 7.2% of eicosapentaenoic acid+docosahexaenoic acid were obtained using Aspergillus niger lipase and Rhizopus javanicus lipase, decreasing the n-6/n-3 fatty acids ratio of soybean oil (11:1 to 3.5:1 and 4.7:1, respectively). The best reaction conditions were: initial water content of lipase of 0.86% (w/w), sardine-free faty acids:soybean oil mole ratio of 3:1 and reaction time of 36h, at 40°C. The significant factors for the acidolysis reaction were the sardine-free fatty acids:soybean oil mole ratio and reaction time. The characterization of structured triacylglycerols was obtained using easy ambient sonic-spray ionization mass spectrometry. The enzymatic reaction led to the formation of many structured triacylglycerols containing eicosapentaenoic acid, docosahexaenoic acid or both polyunsaturated fatty acids.

The 3D model of the lipase/acyltransferase from Candida parapsilosis, a tool for the elucidation of structural determinants in CAL-A lipase superfamily

Because lipids are hydrophobic, the development of efficient bioconversions in aqueous media free of organic solvents is particularly challenging for green oleochemistry. Within this aim, enzymes exhibiting various abilities to catalyze acyltransfer reaction in water/lipid systems have been identified. Among these, CpLIP2 from Candida parapsilosis has been characterized as a lipase/acyltransferase, able to catalyze acyltransfer reactions preferentially to hydrolysis in the presence of particularly low acyl acceptor concentration and high thermodynamic activity of water (aw>0.9). Lipase/acyltransferases are thus of great interest, being able to produce new esters at concentrations above the thermodynamic equilibrium of hydrolysis/esterification with limited to no release of free fatty acids. Here, we present a 3D model of CpLIP2 based on homologies with crystallographic structures of Pseudozyma antarctica lipase A. Indeed, the two enzymes have 31% of identity in their primary sequence, yielding a same general structure, but different catalytic properties. The quality of the calculated CpLIP2 model was confirmed by several methods. Limited proteolysis confirmed the location of some loops at the surface of the protein 3D model. Directed mutagenesis also supported the structural model constructed on CAL-A template: the functional properties of various mutants were consistent with their structure-based putative involvement in the oxyanion hole, substrate specificity, acyltransfer or hydrolysis catalysis and structural stability. The CpLIP2 3D model, in comparison with CAL-A 3D structure, brings insights for the elucidation and improvement of the structural determinants involved in the exceptional acyltransferase properties of this promising biocatalyst and of homologous enzymes of the same family.

Homologous yeast lipases/acyltransferases exhibit remarkable cold-active properties

Lipases/acyltransferases catalyse acyltransfer to various nucleophiles preferentially to hydrolysis even in aqueous media with high thermodynamic activity of water (a w >0.9). Characterization of hydrolysis and acyltransfer activities in a large range of temperature (5 to 80 °C) of secreted recombinant homologous lipases of the Pseudozyma antarctica lipase A superfamily (CaLA) expressed in Pichia pastoris, enlighten the exceptional cold-activity of two remarkable lipases/acyltransferases: CpLIP2 from Candida parapsilosis and CtroL4 from Candida tropicalis. The activation energy of the reactions catalysed by CpLIP2 and CtroL4 was 18-23 kJ mol(-1) for hydrolysis and less than 15 kJ mol(-1) for transesterification between 5 and 35 °C, while it was respectively 43 and 47 kJ mol(-1) with the thermostable CaLA. A remarkable consequence is the high rate of the reactions catalysed by CpLIP2 and CtroL4 at very low temperatures, with CpLIP2 displaying at 5 °C 65 % of its alcoholysis activity and 45 % of its hydrolysis activity at 30 °C. These results suggest that, within the CaLA superfamily and its homologous subgroups, common structural determinants might allow both acyltransfer and cold-active properties. Such biocatalysts are of great interest for the efficient synthesis or functionalization of temperature-sensitive lipid derivatives, or more generally to lessen the environmental impact of biocatalytic processes.

Incorporation of omega-3 polyunsaturated fatty acids into soybean lecithin: effect of amines and divalent cations on transesterification by lipases

The transesterification of soybean lecithin with methyl esters of EPA and DHA in an organic solvent (hexane) using various commercially available lipases was studied. Lipases produced by Candida antarctica, Pseudomonas fluorescens, Burkholderia cepacia, Mucor miehei, Thermomyces lanuginosus and Rhizomucor miehei were compared, in the absence or presence of histidine, arginine, urea, Ca²⁺, Mg²⁺, or a combination of urea and divalent cations (additives at 5 % of the total lipid mass). Transesterification using the R. miehei enzyme reached 11.32 and 12.30 % in the presence of Ca²⁺ or Mg²⁺ respectively, and 8.58 and 9.31 % when urea was also added. These were the greatest degrees of transesterification obtained. The results suggest the potential use of this immobilized lipase as a catalyst for interesterification reactions in organic solvent systems with low water content.

Plastic fats from sal, mango and palm oil by lipase catalyzed interesterification

Speciality plastic fats with no trans fatty acids suitable for use in bakery and as vanaspati substitute were prepared by interesterification of blends of palm stearin (PSt) with sal and mango fats using Lipozyme TLIM lipase as catalyst. The blends containing PSt/sal or PSt/mango showed short melting range and hence are not suitable as bakery shortenings. Lipase catalysed interesterification extended the plasticity or melting range of all the blends. The blends containing higher proportion of PSt with sal fat (50/50) were harder having high solids at and above body temperature and hence cannot be used as bakery shortenings. The blends with PSt/sal (30-40/60-70) after interesterification showed melting profiles similar to those of commercial hydrogenated bakery fats. Similarly, the blends containing PSt/mango (30-40/60-70) after interesterification also showed melting profiles similar to those of commercial hydrogenated shortenings. The slip melting point and solidification characteristics also confirm the plastic nature of these samples. The improvement in plasticity after interesterification is due to formation of higher melting as well as lower melting triglycerides during lipase catalysed interesterification.