Biochemical and structural characterization of triacylglycerol lipase from Penicillium cyclopium

Directed evolution of Aspergillus oryzae lipase for the efficient resolution of (R,S)-ethyl-2-(4-hydroxyphenoxy) propanoate

Aspergillus oryzae lipase (AOL) is a potential biocatalyst for industrial application. In this study, a mutant lipase AOL-3^F38N/V230R was screened through two rounds of directed evolution, resulting in a fourfold increase in lipase activity, and threefold in catalytic efficiency (k_cat/K_m), while maintaining its excellent stereoselectivity. AOL-3^F38N/V230R enzyme activity was maximum at pH 7.5 and also at 40 °C. And compared with wild-type AOL-3, AOL-3^F38N/V230R preferentially hydrolyzed the fatty acid ethyl ester carbon chain length from C4 to C6-C10. In the same catalytic reaction conditions, the conversion of (R,S)-ethyl-2-(4-hydroxyphenoxy) propanoate ((R,S)-EHPP) by AOL-3^F38N/V230R can be increased 169.7% compared to the original enzyme. The e.e._s of (R,S)-EHPP achieved 99.4% and conversion about 50.2% with E value being 829.0. Therefore, AOL-3^F38N/V230R was a potential biocatalyst for obtaining key chiral compounds for aryloxyphenoxy propionate (APP) herbicides.

Development of a Pichia pastoris whole-cell biocatalyst with overexpression of mutant lipase I PCLG47I from Penicillium cyclopium for biodiesel production

Biodiesel is efficiently produced by a lipase whole-cell biocatalyst with high activity and thermostability at low temperature.

Improvement in thermostability of an alkaline lipase I from Penicillium cyclopium by directed evolution

A novel alkaline-stable lipase I from Penicillium cyclopium with improved thermostability was prepared by molecular modification.

Lipolytic potential of Aspergillus japonicus LAB01: production, partial purification, and characterisation of an extracellular lipase

Lipolytic potential of Aspergillus japonicus LAB01 was investigated by describing the catalytic properties and stability of a secreted extracellular lipase. Enzyme production was considered high under room temperature after 4 days using sunflower oil and a combination of casein with sodium nitrate. Lipase was partially purified by 3.9-fold, resulting in a 44.2% yield using ammonium sulphate precipitation (60%) quantified with Superose 12 HR gel filtration chromatography. The activity of the enzyme was maximised at pH 8.5, and the enzyme demonstrated stability under alkaline conditions. The optimum temperature was found to be 45°C, and the enzyme was stable for up to 100 minutes, with more than 80% of initial activity remaining after incubation at this temperature. Partially purified enzyme showed reasonable stability with triton X-100 and was activated in the presence of organic solvents (toluene, hexane, and methanol). Among the tested ions, only Cu²⁺, Ni²⁺, and Al³⁺ showed inhibitory effects. Substrate specificity of the lipase was higher for C14 among various p-nitrophenyl esters assayed. The K_M and V_max values of the purified enzyme for p-nitrophenyl palmitate were 0.13 mM and 12.58 umol/(L·min), respectively. These features render a novel biocatalyst for industrial applications.

Biochemistry of lipolytic enzymes secreted by Penicillium solitum and Cladosporium cladosporioides

Two distinct extracellular lipases were obtained from Penicillium solitum 194A, isolated from domestic compost, and Cladosporium cladosporioides 194B, isolated from dairy wastewater. These alkaline enzymes had molecular masses of 42 and 30 kDa, respectively. The P. solitum 194A lipase differed in mass from previously reported enzyme, indicating that it is a novel lipase, and indicating that penicillia can secrete lipase isoenzymes. The C. cladosporioides lipase was more active on esters of medium-chain acids, whereas the P. solitum lipase was more active on longer chained substrates. The C. cladosporioides enzyme displayed higher thermal stability than the P. solitum lipase, preserving full activity up to 48 °C and showing a T50 (10 min) of 60 °C. Their different catalytic properties and good protein stability should make these enzymes suitable for biotechnological applications. Furthermore, the combined use of these two fungal strains may prove to be valuable in lipid-rich waste management.

Production of extracellular lipases by Rhizopus oligosporus in a stirred fermentor

The present investigation deals with the kinetics of submerged extracellular lipases fermentation by both wild and mutant strains of Rhizopus oligosporus var.microsporus in a laboratory scale stirred fermentor. Other parameters studied were inoculum size, pH, agitation and rate of aeration. It was found that the growth and lipases production was increased gradually and reached its maximum 9.07± 0.42(a) U mL(-1) (W) and 42.49 ± 3.91(a) U mL(-1) (M) after 30h of fermentation for both wild and mutant strain. There is overall increase of 109% (W) and 124% (M) in the production of extracellular lipases as compared to shake flask. Another significant finding of the present study is that the fermentation period is reduced to 30 h in case of wild and 23 h in case of mutant from 48 h in shake flask studies. The specific productivity of mutant strain (qp = 377.3 U/g cells/h) was several folds higher than wild strain. The specific production rate and growth coefficient revealed the hyperproducibility of extracellular lipases using mutant IIB-63NTG-7.

Methods for detection and characterization of lipases: A comprehensive review

Microbial lipases are very prominent biocatalysts because of their ability to catalyze a wide variety of reactions in aqueous and non-aqueous media. The chemo-, regio- and enantio-specific behaviour of these enzymes has caused tremendous interest among scientists and industrialists. Lipases from a large number of bacterial, fungal and a few plant and animal sources have been purified to homogeneity. This article presents a critical review of different strategies which have been employed for the detection, purification and characterization of microbial lipases.

Determination of tributyrin and its metabolite butyrate in Wistar rat plasma samples by gas chromatography/mass spectrometry

A gas chromatographic (GC) method with mass spectrometric (MS) detection was developed for the determination of tributyrin and its metabolite butyrate in rat plasma. Following precipitation of plasma protein with acetonitrile, the analytes in the samples were separated on a DB-5ms capillary column with helium as carrier gas. Phenylmethylsulfonyl fluoride (PMSF), an inhibitor for serine proteases, papain and acetylcholinesterase, was found to be essential to inhibit the activity of enzyme(s) responsible for the hydrolysis of tributyrin in both rat and human blood samples. The enzyme inhibitor in 5 mM (final concentration) was added immediately into the blood samples after collection to prevent the hydrolysis. The linear concentration ranges for tributyrin and butyrate were 0.1-2.0 and 1-20 microM, respectively. The coefficients of variation for intra-day and inter-day assays for tributyrin were all <10%, and those for butyrate were also <10%, except for the lowest concentration (1 microM), which was less than 20%. The accuracy of all concentration determinations ranged from 96.0-110.0%. The limit of quantification (LOQ) was 0.1 microM for tributyrin and 1.0 microM for butyrate. This method could detect tributyrin and butyrate simultaneously, and represents an improvement in sensitivity for the detection of tributyrin compared with the previous gas chromatography-flame ionization detection (GC-FID) method.

Cloning of an alkaline lipase gene from Penicillium cyclopium and its expression in Escherichia coli

The gene encoding an alkaline lipase of Penicillium cyclopium PG37 was cloned with four steps of PCR amplification based on different principles. The cloned gene was 1,480 nucleotides in length, consisted of 94 bp of promoter region, and had 6 exons and 5 short introns ranging from 50 to 70 nucleotides. The open reading frame encoded a protein of 285 amino acid residues consisting of a 27-AA signal peptide and a 258-AA mature peptide, with a conserved motif of Gly-X-Ser-X-Gly shared by all types of alkaline lipases. However, this protein had a low homology with lipases of P. camembertii (22.9%), Humicola lanuginosa (25.6%), and Rhizomucor miehei (22.3%) at the amino acid level. The mature peptide-encoding cDNA was cloned and expressed in Escherichia coli on pET-30a for confirmation. A distinct band with a M.W. of 33 kDa was detected on SDS-PAGE. Results of a Western blot analysis and an enzyme activity assay verified the recombinant 33-kDa protein as an alkaline lipase. Its catalytic properties were not changed when compared with its natural counterpart.

Lipase-catalysed hydrolysis of short-chain substrates in solution and in emulsion: a kinetic study

We have studied the enzymatic hydrolysis of solutions and emulsions of vinyl propionate, vinyl butyrate and tripropionin by lipases of various origin and specificity. Kinetic studies of the hydrolysis of short-chain substrates by microbial triacylglycerol lipases from Rhizopus oryzae, Mucor miehei, Candida rugosa, Candida antarctica A and by (phospho)lipase from guinea-pig pancreas show that these lipolytic enzymes follow the Michaelis-Menten model. Surprisingly, the activity against solutions of tripropionin and vinyl esters ranges from 70% to 90% of that determined against emulsions. In contrast, a non-hyperbolic (sigmoidal) dependence of enzyme activity on ester concentration is found with human pancreatic lipase, triacylglycerol lipase from Humicola lanuginosa (Thermomyces lanuginosa) and partial acylglycerol lipase from Penicillium camembertii and the same substrates. In all cases, no abrupt jump in activity (interfacial activation) is observed at substrate concentration corresponding to the solubility limit of the esters. Maximal lipolytic activity is always obtained in the presence of emulsified ester. Despite progress in the understanding of structure-function of lipases, interpretation of the mode of action of lipases active against solutions of short-chain substrates remains difficult. Actually, it is not known whether these enzymes, which possess a lid structure, are in open or/and closed conformation in the bulk phase and whether the opening of the lid that gives access to the catalytic triad is triggered by interaction of the enzyme molecule with monomeric substrates or/and multimolecular aggregates (micelles) both present in the bulk phase. From the comparison of the behaviour of lipases used in this study which, in some cases, follow the Michaelis-Menten model and, in others, deviate from classical kinetics, it appears that the activity of classical lipases against soluble short-chain vinyl esters and tripropionin depends not only on specific interaction with single substrate molecules at the catalytic site of the enzyme but also on physico-chemical parameters related to the state of association of the substrate dispersed in the aqueous phase. It is assumed that the interaction of lipase with soluble multimolecular aggregates of tripropionin or short-chain vinyl esters or the formation of enzyme-substrate mixed micelles with ester bound to lipase, might represent a crucial step that triggers the structural transition to the open enzyme conformation by displacement of the lid.

Purification and characterization of an extracellular lipase from Penicillium candidum

Penicillium candidum produces and secretes a single extracellular lipase with a monomer molecular weight of 29 kDa. However, this enzyme forms dimers and higher molecular weight aggregates under nondenaturing conditions. The lipase from P. candidum was purified 37-fold using Octyl-Sepharose CL-4B and DEAE-Sephadex columns. The optimal assay conditions for lipase activity were 35 degrees C and pH 9. The lipase was stable in the pH range of 5-6 with a pl of 5.5, but rapid loss of the enzyme activity was observed above 25 degrees C. Tributyrin was found to be the best substrate for the P. candidum lipase, among those tested. Metal ions such as Fe2+ and Cu2+ inhibited enzymatic activity and only Ca2+ was able to slightly enhance lipase activity. Ionic detergents inhibited the activity of the enzyme, whereas nonionic detergents stimulated lipase activity.

Kinetic properties of Penicillium cyclopium lipases studied with vinyl esters

Penicillium cyclopium produces two lipases with different substrate specificities. Lipase I is predominantly active on triacylglycerols whereas lipase II hydrolyzes mono- and diacylglycerols but not triacylglycerols. In this study, we compared the kinetic properties of P. cyclopium lipases and human pancreatic lipase, a classical triacylglycerol lipase, by using vinyl esters as substrates. Results indicate that P. cyclopium lipases I and II and human pancreatic lipase hydrolyze solutions of vinyl propionate or vinyl butyrate at high relative rates compared with emulsions of the same esters, although, in all cases, maximal activity is reached in the presence of emulsified particles, at substrate concentrations above the solubility limit. It appears that partially water-soluble short-chain vinyl esters are suitable substrates for comparing the activity of lipolytic enzymes of different origin and specificity toward esters in solution and in emulsion.

Purification and characterization of an extracellular lipase from a thermophilic Rhizopus oryzae strain isolated from palm fruit

We have isolated a lipolytic strain from palm fruit that was identified as a Rhizopus oryzae. Culture conditions were optimized and highest lipase production amounting to 120 U/ml was achieved after 4 days of cultivation. The extracellular lipase was purified 1200-fold by ammonium sulfate precipitation, sulphopropyl-Sepharose chromatography, Sephadex G 75 gel filtration and a second sulphopropyl-Sepharose chromatography. The specific activity of the purified enzyme was 8800 U/mg. The lipolytic enzyme has a molecular mass of 32 kDa by SDS-polyacrylamide gel electrophoresis and gel filtration. The enzyme exhibited a single band in active polyacrylamide gel electrophoresis and its isoelectric point was 7.6. Analysis of Rhizopus oryzae lipase by RP-HPLC confirmed the homogeneity of the enzyme preparation. Determination of the N-terminal sequence over 19 amino acid residues showed a high homology with lipases of the same genus. The optimum pH for enzyme activity was 7.5. Lipase was stable in the pH range from 4.5 to 7.5. The optimum temperature for lipase activity was 35 degrees C and about 65% of its activity was retained after incubation at 45 degrees C for 30 min. The lipolytic enzyme was inhibited by Triton X100, SDS, and metal ions such as Fe(3+), Cu(2+), Hg(2+) and Fe(2+). Lipase activity against triolein was enhanced by sodium cholate or taurocholate. The purified lipase had a preference for the hydrolysis of saturated fatty acid chains (C(8)-C(18)) and a 1, 3-position specificity. It showed a good stability in organic solvents and especially in long chain-fatty alcohol. The enzyme poorly hydrolyzed triacylglycerols containing n-3 polyunsaturated fatty acids, and appeared as a suitable biocatalyst for selective esterification of sardine free fatty acids with hexanol as substrate. About 76% of sardine free fatty acids were esterified after 30 h reaction whereas 90% of docosahexaenoic acid (DHA) was recovered in the unesterified fatty acids.

Isolation, purification, and characterization of a cold-active lipase from Aspergillus nidulans

Aspergillus nidulans WG312 strain secreted lipase activity when cultured in liquid media with olive oil as carbon source. Highest lipase productivity was found when the mycelium was grown at 30 degrees C in a rich medium. The new enzyme was purified to homogeneity from the extracellular culture of A. nidulans by phenyl-Sepharose chromatography and affinity binding on linolenic acid-agarose. The lipase was monomeric with an apparent M(r) of 29 kDa and a pI of 4.85 and showed no glycosylation. Kinetic of enzyme activity versus substrate concentration showed a typical lipase behavior, with K(M) and K(cat) values of 0.28 mM and 494 s(-)(1) and 0.30 mM and 320 s(-)(1) for the isotropic solution and for the turbid emulsion, respectively. All glycerides assayed were hydrolyzed efficiently by the enzyme, but this showed preference toward esters of short- and middle-chain fatty acids. The optimum temperature and pH for the lipolytic activity were 40 degrees C and 6.5, with high activity in the range 0-20 degrees C and reduced thermal stability.