Development of an amphiphilic matrix for immobilization of <Emphasis Type="Italic">Candida antartica</Emphasis> lipase B for biodiesel production

Biodiesel has been greatly interested as an alternative fuel and is produced by a transesterification reaction of oil with alcohol. Recently, microbial lipases have been used for biodiesel production. Among the microbial lipase, immobilized Candida antartica lipase B (CALB) is the most widely used. However, CALB is unstable and shows low catalytic efficiency in the reaction media because the reaction media contains a high concentration of methanol and the lipase is also inhibited by the by-product glycerol. In this study, to overcome these limitations, we developed an amphiphilic matrix to immobilize CALB. The immobilized lipase in an amphiphilic matrix with 80% ethyltrimethoxysilane (ETMS) in tetramethoxysilane (TMOS) and pretreated with oil showed the highest specific activity and biodiesel conversion ratio; about 90% biodiesel conversion in 24 h at an initial molar ratio of 1: 1 (oil: methanol) with stepwise methanol feeding in order to adjust the net molar ratio to be 1: 3.     

Differences in N-glycan structures foundon recombinant IgA1 and IgA2 producedin murine myeloma and CHO cell lines

The development and production of recombinant monoclonal antibodies is well established. Although most of these are IgGs, there is also great interest in producing recombinant IgAs since this isotype plays a critical role in providing immunologic protection at mucosal surfaces. the choice of expression system for production of recombinant antibodies is crucial because they are glycoproteins containing at least one N-linked carbohydrate. these glycans have been shown to contribute to the stability, pharmacokinetics and biologic function of antibodies. We have produced recombinant human IgA1 and all three allotypes of IgA2 in murine myeloma and CHo cell lines to systematically characterize and compare the N-linked glycans. Recombinant IgAs produced in murine myelomas differ significantly from IgA found in humans in that they contain the highly immunogenic Galα(1,3)Gal epitope and N-glycolylneuraminic acid residues, indicating that murine myeloma is not the optimal expression system for the production of human IgA. In contrast, IgAs produced in CHo cells contained glycans that were more similar to those found on human IgA. expression of IgA1 and IgA2 in Lec2 and Lec8 cell lines that are defective in glycan processing resulted in a less complex pool of N-glycans. In addition, the level of sialylation of rIgAs produced in murine and CHo cells was significantly lower than that previously reported for serum IgA1. these data underscore the importance of choosing the appropriate cell line for the production of glycoproteins with therapeutic potential.Key words: recombinant antibody, IgA, glycosylation, expression system, mass spectrometry     

Local kallikrein�Ckinin system is involved in podocyte apoptosis under diabetic conditions

The kallikrein-kinin system (KKS) serves as the physiologic counterbalance to the renin-angiotensin system. This study was conducted to examine the changes in the expression of KKS components in podocytes under diabetic conditions and to elucidate the functional role of bradykinin (BK) in diabetes-associated podocyte apoptosis. Thirty-two rats were injected with either diluent (n = 16, C) or with streptozotocin intraperitoneally (n = 16, DM), and 8 rats from each group were treated with BK infusion for 6 weeks. Immortalized mouse podocytes were cultured in media containing 5.6 mmol/l glucose (NG), NG + 10(-7) mol/l AII (AII), or 30 mmol/l glucose (HG) with or without 10(-8) mol/l BK. Urinary albumin excretion was significantly higher in DM rats, and this increase was ameliorated by BK. Not only kininogen, kallikrein, and BK B1- and B2-receptor expression but also BK levels were significantly decreased in DM glomeruli and in cultured podocytes exposed to HG. The changes in the expressions of apoptosis-related molecules and the increase in the number of apoptotic cells in DM glomeruli as well as in HG- and AII-stimulated podocytes were significantly abrogated by BK. The suppressed KSS within podocytes under diabetic condition was associated with podocyte apoptosis, suggesting that BK may be beneficial in preventing podocyte loss in diabetic nephropathy.     

Synthesis and antibacterial activities of novel oxazolidinones having cyclic sulfonamide moieties

The synthesis of a new series of oxazolidinones having cyclic sulfonamide moieties is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria were tested and the effect of substituents on the oxazolidinone ring was investigated. A particular compound 15g having [1,2,5]thiadiazolidin-1,1-dioxide moiety showed the most potent antibacterial activity.     

Inositol 1,4,5-Trisphosphate Receptor in Chromaffin Secretory Granules and Its Relation to Chromogranins

The inositol 1,4,5-trisphosphate (IP₃)-mediated intracellular Ca²⁺ releases in secretory cells play vital roles in controlling not only the intracellular Ca²⁺ concentrations but also the Ca²⁺-dependent exocytotic processes. Of intracellular organelles that release Ca²⁺ in response to IP₃, secretory granules stand out as the most prominent organelle and are responsible for the majority of IP₃-dependent Ca²⁺ releases in the cytoplasm of chromaffin cells. Bovine chromaffin granules were the first granules that demonstrated the IP₃-mediated Ca²⁺ release as well as the presence of the IP₃ receptor (IP₃R) in granule membranes. Secretory granules contain all three (type 1, 2, and 3) IP₃R isoforms, and 58–69% of total cellular IP₃R isoforms are expressed in bovine chromaffin granules. Moreover, secretory granules contain large amounts (2–4 mM) of chromogranins and secretogranins; chromogranins A and B, and secretogranin II being the major species. Chromogranins A and B, and secretogranin II are high-capacity, low-affinity Ca²⁺ binding proteins, binding 30–93 mol of Ca²⁺/mol of protein with dissociation constants of 1.5–4.0 mM. Due to this high Ca²⁺ storage properties of chromogranins secretory granules contain ~40 mM Ca²⁺. Furthermore, chromogranins A and B directly interact with the IP₃Rs and modulate the IP₃R/Ca²⁺ channels, i.e., increasing the open probability and the mean open time of the channels 8- to 16-fold and 9- to 42-fold, respectively. Coupled chromogranins change the IP₃R/Ca²⁺ channels to a more ordered, release-ready state, whereby making the IP₃R/Ca²⁺ channels significantly more sensitive to IP₃.     

Protective effect of ginseng sapogenins against 2,2'-azobis (1-aminopropane) dihydrochloride (AAPH)-induced LLC-PK₁ cell damage

The effect of ginseng sapogenins, aglycone parts of ginsenosides, against oxidative damage by radical generator, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH), in renal epithelial LLC-PK(1) cells was investigated to identify the structural characteristics of sapogenins to have renoprotective effects. Of the tested sapogenins, Δ(20(21))-protopanaxatriol showed the strongest protective effect against the AAPH-induced LLC-PK(1) cell damage. Based on the structure and stronger activity of Δ(20(21))-protopanaxatriol than the other sapogenins, the hydroxyl group in C-6 and double bond in C-20(21) position were important for renoprotective effect of sapogenin against oxidative stress.