Papaya (Carica papaya) lipase with some distinct acyl and alkyl specificities as compared with microbial lipases

Lipase from papaya (Carica papaya) latex (CPL), Candida antarctica lipase B (Novozym 435, NOV) and Rhizomucor miehei lipase (Lipozyme IM 20, LIP) were used as biocatalysts for the esterification of caprylic acid with straight-chain saturated C(4)-C(18) alcohols and unsaturated C(18) alcohols, such as cis-9-octadecenyl (oleyl, C(18:1), n-9), cis-6-octadecenyl (petroselinyl, C(18:1), n-12), cis-9,cis-12-octadecadienyl (linoleyl, C(18:2), n-6), all-cis-9,12,15-octadecatrienyl (alpha-linolenyl, C(18:3), n-3) and all-cis-6,9,12-octadecatrienyl (gamma-linolenyl, C(18:3), n-6) alcohols. With CPL, highest activity was found in the esterification of octanol and decanol, whereas both NOV and LIP showed a broad chain-length-specificity for the alcohols. CPL, as opposed to the microbial lipases, strongly discriminated against all the saturated long-chain ( > C(12)) and unsaturated C(18) alcohols.     

Pulse radiolytic oxidation of beta-carotene with halogenated alkylperoxyl radicals in a quaternary microemulsion: formation of retinol

Pulse radiolytically generated halogenated alkylperoxyl radicals, namely CCl3OO*, CBr3OO*, CHCl2OO*, CHBr2OO*, etc. have been employed for a study of the oxidation of beta-carotene in a quaternary microemulsion. All these halogenated alkylperoxyl radicals produce a radical cation (absorption maximum at 840 nm), either via the initial formation of an adduct (absorption maximum at 740 nm), or by direct reaction. There was a considerable blue shift of both absorption peaks in the present system as compared to those earlier reported in non-polar as well as in micellar media. An additional intense absorption peak at approximately 345 nm was noted at a longer time scale and was stable up to 5 ms. On irradiation with a large number of electron pulses, a stable product with an absorption maximum at 315 nm appeared. On excitation at 315 nm, this product gave a fluorescence spectrum with an emission maximum at 525 nm. The absorption and fluorescence spectra of the stable product compared with those of retinol; this was further confirmed by HPLC analysis. A suitable mechanism has been proposed.     

New bioactive aromatic compounds from Vismia guianensis

Five benzophenones, vismiaguianones A-E, and two benzocoumarins, vismiaguianins A and B were isolated from the CHCl3 extract of the roots of Vismia guianensis by bioassay-directed fractionation using the DNA strand-scission assay and KB cell line. Of the isolates obtained, vismiaguianone B exhibited DNA strand-scission activity, whereas vismiaguianones D and E and vismiaguianin A were found to be significantly cytotoxic.     

Establishment of forskolin yielding transformed cell suspension cultures of Coleus forskohlii as controlled by different factors

Suspension cultures derived from gall calli which were obtained following infection with Agrobacterium tumefaciens (C58) were established in Coleus forskohlii. Cell line selection following single cell cloning or cell aggregate cloning was carried out to select cell lines capable of fast growth and for producing high level of forskolin. A fast growing cell line (GSO-5/7) thus selected was found to accumulate 0.021% forskolin in 42 days. The effect of cultural conditions on cell growth was studied to identify factors influencing biomass yield. Cell growth in suspension was found to be influenced significantly by carbon source, initial cell density and light or dark condition. Optimal cell growth (20 fold increase in biomass in a 42 day period) was obtained when the cells were grown in dark condition in B5O media containing 3% sucrose as sole carbon source with an initial cell density of 1.5 x 10(5) cells per ml. Forskolin accumulation was maximum (0.021%) in the stationary phase of cell growth. These suspension cultures showed continuous and stable production of forskolin.     

Production of extracellular enzymes by two Pleurotus species using banana pseudostem biomass

The degradation of lignocellulosic biomass of banana pseudoste was investigated during solid state fermentation (SSF) by P. ostreatus and P. sajor-caju. Both organisms proved to be efficient degraders of banana pseudostem biomass. P.ostreatus degraded hemicellulose (40% of dry weight, d.w.) better than cellulose (17.5% of d.w.) and lignin (10% of d.w.). P. sajor-caju also degraded hemicellulose (31% of d.w.) better than cellulose (12.4% of d.w.) and lignin (6% of d.w.). In both cases, a preferential removal of hemicellulose during the initial growth period and a delayed degradation of lignin were observed. The kinetics of cellulolytic, hemicellulolytic and lignolytic enzyme production in liquid culture were also examined. The activities of CMCase and β-glucosidase were highest at 16 days of growth and avicelase activity was at its maximum after 24 days (CMCase - 1.1 IU/ml, β-glucosidase - 0.09 IU/ml in the case of P. ostreatus; CMCase - 1.0 IU/ml, β-glucosidase - 0.087 - IU/ml in the case of P. sajor-caju.). Xylanase and laccase activity reached their maximum after day 16 and day 24 of incubation, respectively. (Xylanase - 1.1 IU/ml and laccase 3.0 IU/ml in the case of P. ostreatus; xylanase - 1.0 IU/ml and laccase - 3.6 IU/ml in the case of P. sajor-caju.). The efficient degrading capacity of test fungi demonstrated their potential use in the conversion of banana pseudostem biomass into mycelial protein-rich fermented animal feed.     

Thermal stresses from large volumetric expansion during freezing of biomaterials.

Thermal stresses were studied in freezing of biomaterials containing significant amounts of water. An apparent specific heat formulation of the energy equation and a viscoelastic model for the mechanics problem were used to analyze the transient axi-symmetric freezing of a long cylinder. Viscoelastic properties were measured in an Instron machine. Results show that, before phase change occurs at any location, both radial and circumferential stresses are tensile and keep increasing until phase change begins. The maximum principal tensile stress during phase change increases with a decrease in boundary temperature (faster cooling). This is consistent with experimentally observed fractures at a lower boundary temperature. Large volumetric expansion during water to ice transformation was shown to be the primary contributor to large stress development. For very rapid freezing, relaxation may not be significant, and an elastic model may be sufficient.     

Characterization of IgM of Indian major carps and their cross-reactivity with anti-fish IgM antibodies

Indian major carps (IMC), rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) were immunized with bovine serum albumin and the serum immunoglobulin M (IgM) was purified by affinity chromatography. The heavy and light chain of IgM of all the three species of IMC were about 88 and 26 kDa, respectively. Anti-fish IgM antibody against all the three species were raised in mice and the reaction of anti-fish IgM antibodies with IgM of all the three species of IMC were studied by Western blot. The anti-fish IgM antibodies reacted strongly with the heavy chain of the same species against which it was raised while the reactions with the heavy chain of other species were milder indicating some degree of epitope sharing among the heavy chains of IgM of IMCs. However, there was no cross-reaction with the light chain of any of the IgM.