53 research outputs found
Engineering of factors determining alpha-amylase and cyclodextrin glycosyltranferase specificity in the cyclodextrin glycosyltransferase form Thermoanaerobacterium thermosulfurigenes EM1
The starch-degrading enzymes alpha-amylase and cyclodextrin glycosyltransferase (CGTase) are functionally and structurally closely related, with CGTases containing two additional domains (called D and E) compared to the three domains of alpha-amylases (A, B and C). Amino acid residue 196 (Thermoanaerobacterium thermosulfurigenes EM1 CGTase numbering) occupies a dominant position in the active-site cleft. All alpha-amylases studied have a small residue at this position (Gly, Leu, Ser, Thr or Val), in contrast to CGTases which have a more bulky aromatic residue (Tyr or Phe) at this position, which is highly conserved. Characterization of the F196G mutant CGTase of T. thermosulfurigenes EM1 revealed that, for unknown reasons, apart from the F196G mutation, domain E as well as a part of domain D had become deleted [mutant F196G(Delta'DE)]. This, nevertheless, did not prevent the purification of a stable and active mutant CGTase protein (62 kDa). The mutant protein was more similar to an alpha-amylase protein in terms of the identity of residue 196, and in the domain structure containing, however some additional C-terminal structure. The mutant showed a strongly reduced temperature optimum. Due to a frameshift mutation in mutant F196G, a separate protein of 19 kDa with the DE domains was also produced. Mutant F196G(Delta'DE) displayed a strongly reduced raw-starch-binding capacity. similar to the situation in most alpha-amylases that lack a raw-starch-binding E domain. Compared to wild-type CGTase, cyclization, coupling and disproportionation activities had become drastically reduced in the mutant F196G(Delta'DE), but its saccharifying activity had doubled, reaching the highest level ever reported for a CGTase. Under industrial production process conditions, wild-type CGTase converted starch into 35% cyclodextrins and 11% linear oligosaccharides (glucose, maltose and maltotriose), whereas mutant F196G(Delta'DE) converted starch into 21% cyclodextrins and 18% into linear oligosaccharides. These biochemical characteristics indicate a clear shift from CGTase to alpha-amylase specificity
Engineering of cyclodextrin product specifity and pH optima of the thermostable cyclodextrin glycosyltransferase from Thermoanaerobacterium thermosulfurigenes EM1
Engineering of cyclodextrin product specifity and pH optima of the thermostable cyclodextrin glycosyltransferase from Thermoanaerobacterium thermosulfurigenes EM1
Over de bepaling van stikstof, gebonden als calcium-cyaanamide in kalkstikstof of stikstofkalk
Engineering of cyclodextrin product specifity and pH optima of the thermostable cyclodextrin glycosyltransferase from Thermoanaerobacterium thermosulfurigenes EM1
Denial at the top table: status attributions and implications for marketing
Senior marketing management is seldom represented on the Board of Directors nowadays, reflecting a deteriorating status of the marketing profession. We examine some of the key reasons for marketing’s demise, and discuss how the status of marketing may be restored by demonstrating the value of marketing to the business community. We attribute marketing’s demise to several related key factors: narrow typecasting, marginalisation and limited involvement in product development, questionable marketing curricula, insensitivity toward environmental change, questionable professional standards and roles, and marketing’s apparent lack of accountability to CEOs. Each of these leads to failure to communicate, create, or deliver value within marketing. We argue that a continued inability to deal with marketing’s crisis of representation will further erode the status of the discipline both academically and professionally
Peg-interferon lambda treatment induces robust innate and adaptive immunity in chronic hepatitis B patients
IFN-lambda (IFNλ) is a member of the type III IFN family and is reported to possess anti-pathogen, anti-cancer, and immunomodulatory properties; however, there are limited data regarding its impact on host immune responses in vivo. We performed longitudinal and comprehensive immunosurveillance to assess the ability of pegylated (peg)-IFNλ to augment antiviral host immunity as part of a clinical trial assessing the efficacy of peg-IFNλ in chronic hepatitis B (CHB) patients. These patients were pretreated with directly acting antiviral therapy (entecavir) for 12 weeks with subsequent addition of peg-IFNλ for up to 32 weeks. In a subgroup of patients, the addition of peg-IFNλ provoked high serum levels of antiviral cytokine IL-18. We also observed the enhancement of natural killer cell polyfunctionality and the recovery of a pan-genotypic HBV-specific CD4+ T cells producing IFN-γ with maintenance of HBV-specific CD8+ T cell antiviral and cytotoxic activities. It was only in these patients that we observed strong virological control with reductions in both viral replication and HBV antigen levels. Here, we show for the first time that in vivo peg-IFNλ displays significant immunostimulatory properties with improvements in the main effectors mediating anti-HBV immunity. Interestingly, the maintenance in HBV-specific CD8+ T cells in the presence of peg-IFNλ is in contrast to previous studies showing that peg-IFNa treatment for CHB results in a detrimental effect on the functionality of this important antiviral T cell compartment
Strategies for Controlled Placement of Nanoscale Building Blocks
The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others
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