Phosphoesterase activity and phosphate release from tributyl phosphate by aCitrobacter sp.

Tributyl phosphate (TBP) and other alkyl phosphates represent a class of persistent organophosphorus compounds of widespread use. Biodegradation of the phosphotriesters is postulated to occur through sequential hydrolytic cleavages via the phosphodiester and monoester intermediates to alcohol and inorganic phosphate (P_i). Immobilized cells of aCitrobacter sp. liberated P_i upon challenge with TBP but the reaction was short-lived. In vitro studies with purified phosphomonoesterase (phosphatase) used³¹P nuclear magnetic resonance to demonstrate P_i transfer onto ethanol (phosphotransferase activity). This suggested that in vivo the onset of a futile phosphohydrolytic and transphosphorylation cycle would limit the extent of phosphate production. A mutant deficient in the transphosphorylating phosphomonoesterase showed an extended release of P_i under challenge with TBP that was not subject to the complete and premature reaction termination that precluded application of the parent strain to possible industrial processes for alkyl phosphate biodegradation.     

Effect of polyphenols from Vicia faba L on lipase activity and melanogenesis

Two new flavonoid glycosides, kaempferol 3-O-α-L-rhamnopyranosyl (1→6) (3′′-acetyl)-β-D-galactopyranoside 1 and kaempferol 3-O-α-L-arabinopyranosyl-5-O-α-L-rhamnopyranoside 2, along with six known ones 3–8 were isolated from the flowers of Vicia faba L. (Fabaceae). Methanol extract and the isolated compounds were tested against lipase and melanogenesis inhibition activities and resulted in that compound 2 showed 53 and 77% lipase inhibition activity in concentrations of 400 and 800 μg/mL, respectively. For melanogenesis, compounds 2, 3 and 4 exhibited potent melanogenesis inhibition activity where the melanin content in melanoma cells was decreased to be about 57.5, 56 and 61%, respectively, with no obvious melanocytotoxicity. The rest of compounds showed weak to moderate activity. The results of melanogenesis inhibition activity of this study suggested the potential use of Vicia faba flowers as a skin-whitening agent and reveal the flowers to be a rich source of important phytochemicals with antilipase and melanogenesis inhibitory activity.     

Lipoprotein lipase activity of the fungusRhizopus microsporus

A method is described for the isolation and purification of lipoprotein lipase activity from the culture liquid of the fungusRhizopus microsporus. Some properties of the homogeneous enzyme have been studied: molecular weight 43,000, pI 3.7.     

表面活性剂对脂肪酶活性和选择性的影响

考察了几种表面活性剂对lipaseOF粗酶和纯化酶催化拆分酮基布洛芬的影响。除吐温-80,吐温-60和壬基酚聚氧乙烯醚外,大部分表面活性剂对酶活性有抑制作用,其中只有吐温-80能显著提高酶的立体选择性。酶的活性和选择性与表面活性剂浓度有关。在表面活性剂浓度为最佳(20mg/mL吐温-80或30mg/mL壬基酚聚氧乙烯醚)时lipaseOF粗酶的活性可分别提高13和15倍。加入80mg/mL吐温-80,粗酶和纯化酶的对映体选择率(E值)分别由1.1和8.0增至6.7和>100。     

Synthesis of pyrimidine derivatives of amino acids using pig liver esterase and pancreas lipase.

The parent methyl ester of the N-1 substituted 5-chloropyrimidinone is hydrolysed by pig liver esterase to the corresponding carboxylic acid. The acid chloride was made with PCl5 in toluene, and coupling with benzyl and methyl esters of selected L-amino acids to the corresponding amides was done in dichloromethane in the presence of triethylamine. The benzyl and methyl ester protecting groups were hydrolysed with pancreas lipase or esterase in a pH-stat to yield the corresponding carboxylic acids.     

Angiogenin induces nitric oxide release independently from its RNase activity

Nitric oxide (NO), a biological mediator involved in vascular physiology, was sensed electrochemically using a microelectrode array. Angiogenin was shown to trigger nitric oxide synthase (NOS) activity in human umbilical vein endothelial cells and embryonic stem cell derived endothelial cells independently from its RNase activity.     

A novel lipase enzyme panel exhibiting superior activity and selectivity over lipase B from Candida antarctica for the kinetic resolution of secondary alcohols

A novel, commercially available lipase enzyme panel performing kinetic bioresolutions of a number of secondary alcohols is reported. The secondary alcohols that have been chosen are known from the literature to be particularly challenging substrates to resolve. Following initial screening, four co-solvents were investigated for each lead enzyme in an effort to assess their tolerance to common organic solvents. The superiority of these novel enzymes over lipase B from Candida antarctica (CALB) has been demonstrated.     

Enhanced catalytic activity of lipase encapsulated in PCL nanofibers

Use of biocatalysis for industrial synthetic chemistry is on the verge of significant growth. Enzyme immobilization as an effective strategy for improving the enzyme activity has emerged from developments especially in nanoscience and nanotechnology. Here, lipase from Burkholderia cepacia (LBC), as an example of the luxuriant enzymes, was successfully encapsulated in polycaprolactone (PCL) nanofibers, proven by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Evaluated in both organic and aqueous medium, the activation factor of the encapsulated enzymes in the hydrolysis reaction was generally higher than that in the transesterification reaction. Enhanced catalytic activities were found when 5-20 w/w % of LBC was loaded. The effect of different solvents pretreatment on the activity of immobilized LBC was also investigated. The highest activation factor was found up to 14 for the sample containing acetone-treated LBC/PCL (10 w/w %). The encapsulated lipase reserved 50% of its original activity after the 10th run in the transesterification reaction in hexane medium. The mechanism of activation of lipase catalytic ability based on active PCL nanofiberous matrix is proposed.     

Lipoprotein lipase activity of the fungusRhizopus microsporus

A method is described for the isolation and purification of lipoprotein lipase activity from the culture liquid of the fungusRhizopus microsporus. Some properties of the homogeneous enzyme have been studied: molecular weight 43,000, pI 3.7.Institute of Microbiology, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 373–376, May–June, 1981.     

Interesterification activity of Rhizopus delemar lipase in phospholipid microemulsions

The interesterification of olive oil with palmitic acid catalyzed by Rhizopus delemar lipase was investigated in phospholipid microemulsion systems. Soybean lecithin was used as the amphiphilic component. The maximal reaction rate was obtained at a buffer pH of 5.5–6.0. The reaction rate was also dependent on the W_L (= [H₂O]/[lecithin]) value and attained a maximum at W_L = 5. The reaction rate reached a maximum at a palmitic acid concentration of 350 mM. The molar fraction of the interesterified product 1,3-dipalmitoyl-3-oleoyl glycerol (POP) in the olive oil was enhanced from 2.8 to 65.6 mol% after 24 h of the reaction.     

Quantitative determination of lipase activity by liquid chromatography-mass spectrometry

We developed a novel in vitro lipase assay based on the quantitation of fatty acids by liquid chromatography-mass spectrometry. Oleic acids enzymatically released from triolein substrates were isolated from the reaction mixture by reverse-phase chromatography, ionized in negative mode electrospray mass spectrometry and quantitated with the aid of [(13)C]-oleic acid internal standard. The enzymatic activity was measured by monitoring oleic acid productions at multiple time points. This method overcomes the substrate and pH limitations of conventional techniques and thus serves as a generic lipase activity assay.