Lipase factor (LF) as a characterization parameter to explain the catalytic activity of crude lipases from Candida rugosa, free or immobilized in microemulsion-based organogels

Higher order structure of Mucor miehei lipase and micelle size in cetyltrimethylammonium bromide reverse micellar system

The higher order structure of Mucor miehei lipase and micelle size in a cationic cetyltrimethylammonium bromide (CTAB) reverse micellar system was investigated. Circular dichroic (CD) measurement revealed that the lipase far-UV CD spectra changed markedly, going from buffer solution to the reverse micellar solution, and were very similar for any organic solvent used. The ellipticity of the solubilized lipase in the far-UV region markedly decreased with increasing water content (W(0): molar ratio of water to CTAB), indicating that the secondary structure of lipase changed with the water content. The linear correlation between the W(0) and the micelle size was obtained by measuring dynamic light scattering. From the linear correlation between the micelle size and W(0), the higher order structure of the solubilized lipase appears to be affected directly by the micellar interface. The species and concentration of alcohol as a cosurfactant had an inferior effect on lipase structure. Especially, at ratios of 1-pentanol to CTAB of less than 8, the secondary and tertiary structures of lipase were preserved in the reverse micelles. The CTAB concentration had little effect on the lipase structure in the micelles. The catalytic activity of the lipase solubilized in the CTAB reverse micelles increased with increasing the W(0).

Triggered release of proteins from emulsan–alginate beads

Emulsan/alginate beads were studied for protein adsorption and stability in the context of controlled release. The beads, 400 +/- 80 microm diameter with approximately 10% emulsan content, offer unusual opportunities for delivery of proteins due to the natural ability of emulsan to bind proteins, coupled with the selective biological activation features of this complex lipoheteropolysaccharide. The binding capacity of azo-bovine serum albumin by the emulsan/alginate beads was 0.637 +/- 0.004 vs. 0.170 +/- 0.007 microg/mg for beads formed from alginate alone. In additional protein adsorption experiments, the lipase and subtilisin maintained activity when adsorbed to the emulsan/alginate beads albeit with lower specific activity when compared to the enzyme free in solution. However, the half life of the adsorbed enzyme was significantly higher than the free forms. To explore functional utility of this system, two types of triggered release were studied in the context of these bead systems. First, azo-BSA as a model protein was physically bound to emulsan/alginate beads and then selectively released by triggering with subtilisin, a serine protease, which cleaves the azo dye, sulfanilic acid, from the bound protein. In absence of subtilisin no triggered release was observed. Second, azo-BSA as a prodrug model, was adsorbed to the emulsan/alginate beads and then release of the dye was demonstrated by lipase treatment which cleaves the fatty acid esters from the emulsan structure to release the bound protein. The results establish the versatility and utility of emulsan-based beads for protein binding and triggered release.

Understanding Candida rugosa lipases: an overview

Candida rugosa lipase (CRL) is one of the enzymes most frequently used in biotransformations. However, there are some irreproducibility problems inherent to this biocatalyst, attributed either to differences in lipase loading and isoenzymatic profile or to other medium-engineering effects (temperature, a(w), choice of solvent, etc.). In addition, some other properties (influence of substrate and reaction conditions on the lid movement, differences in the glycosylation degree, post-translational modifications) should not be ruled out. In the present paper the recent developments published in the CRL field are overviewed, focusing on: (a) comparison of structural and biochemical data among isoenzymes (Lip1-Lip5), and their influence in the biocatalytical performance; (b) developments in fermentation technology to achieve new crude C. rugosa lipases; (c) biocatalytical reactivity of each isoenzyme, and methods for characterising them in crude CRL; (d) state-of-the-art of new applications performed with recombinant CRLs, both in CRL-second generation (wild-type recombinant enzymes), as well as in CRL-third generation, (mutants of the wt-CRL).

Current awareness on yeast

In order to keep subscribers up‐to‐date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly‐published material on yeasts. Each bibliography is divided into 10 sections. 1 Books, Reviews & Symposia; 2 General; 3 Biochemistry; 4 Biotechnology; 5 Cell Biology; 6 Gene Expression; 7 Genetics; 8 Physiology; 9 Medical Mycology; 10 Recombinant DNA Technology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted. (4 weeks journals ‐ search completed 10th. Nov. 2004)