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The molecular basis of nonlinear optical (NLO) chiral effects in the amide I region of type I collagen was investigated using sum-frequency generation vibrational spectroscopy; chiral and achiral tensor elements were separated using different input/output beam polarization conditions. Spectra were obtained from native rat tail tendon (RTT) collagen and from cholesteric liquid crystal-like (LC) type I collagen films. Although RTT and LC collagen both possess long-range order, LC collagen lacks the complex hierarchical organization of RTT collagen. Their spectra were compared to assess the role of such organization in NLO chirality. No significant differences were observed between RTT and LC with respect to chiral or achiral spectra. These findings suggest that amide I NLO chiral effects in type I collagen assemblies arise predominantly from the chiral organization of amide chromophores within individual collagen molecules, rather than from supramolecular structures. The study suggests that sum-frequency generation vibrational spectroscopy may be uniquely valuable in exploring fundamental aspects of chiral nonlinearity in complex macromolecular structures.  相似文献   
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In Saccharomyces cerevisiae cells, high external osmolarity leads to the activation of a p38-related mitogen-activated protein (MAP) kinase though Pbs2. Pbs2 tagged with green fluorescent protein (Pbs2-GFP) is evenly distributed in the cytoplasm but excluded from the nucleus before and after exposure to stress. Here we show that a catalytically inactive form of Pbs2 attains a highly polarised localization during osmostress. This phenomenon depends of the osmosensor Sho1 and on a functional Cdc42 GTPase. Cdc42, but not the actin cytoskeleton, influences Sho1-dependent activation of the MAP kinase. Sho1 itself accumulates at sites of polar growth, but independently of stress conditions and Cdc42. These observations allow us to define the sequence of events that occurs during propogation of osmostress signals.  相似文献   
3.
Natural products containing a gamma-butyrolactone ring are abundant in nature; however, few general synthetic approaches to their stereoselective synthesis with broad structural variety are known. In this article, recent developments towards mono- and polycyclic gamma-butyrolactone natural products and analogs are discussed. A special focus is given to asymmetric methods applying transition metal or organocatalysts that allow not only the efficient introduction of a broad variety of functional groups but ideally also the flexible construction of various natural-product-like, polycyclic scaffolds from common precursors.  相似文献   
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Background

30 years ago, the potential of bispecific antibodies to engage cytotoxic T cells for the lysis of cancer cells was discovered. Today a variety of bispecific antibodies against diverse cell surface structures have been developed, the majority of them produced in mammalian cell culture systems. Beside the r28M, described here, no such bispecific antibody is known to be expressed by transgenic livestock, although various biologicals for medical needs are already harvested—mostly from the milk—of these transgenics. In this study we investigated the large-scale purification and biological activity of the bispecific antibody r28M, expressed in the blood of transgenic cattle. This tandem single-chain variable fragment antibody is designed to target human CD28 and the melanoma/glioblastoma-associated cell surface chondroitin sulfate proteoglycan 4 (CSPG4).

Results

With the described optimized purification protocol an average yield of 30 mg enriched r28M fraction out of 2 liters bovine plasma could be obtained. Separation of this enriched fraction by size exclusion chromatography into monomers, dimers and aggregates and further testing regarding the biological activity revealed the monomer fraction as being the most appropriate one to continue working with. The detailed characterization of the antibody’s activity confirmed its high specificity to induce the killing of CSPG4 positive cells. In addition, first insights into tumor cell death pathways mediated by r28M-activated peripheral blood mononuclear cells were gained. In consideration of possible applications in vivo we also tested the effect of the addition of different excipients to r28M.

Conclusion

Summing up, we managed to purify monomeric r28M from bovine plasma in a large-scale preparation and could prove that its biological activity is unaffected and still highly specific and thus, might be applicable for the treatment of melanoma.  相似文献   
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The amounts of lysine-derived crosslinks in collagens from tendon, cartilage, intervertebral disc, and bone and changes in the composition of sternal cartilage glycosaminoglycans were estimated in two lines of chickens, a control-isogenic line and a line that develops scoliosis. In the scoliotic line, scoliosis first appears at 3-4 weeks and progressively increases in severity and incidence so that 90% of the birds express the lesion by week 10. We have reported previously that cartilage, tendon, and bone collagens from scoliotic birds are more soluble than corresponding collagens from normal birds. Herein, collagen crosslinking and altered proteoglycan metabolism are examined as possible mechanisms for the differences in collagen solubility. At 1 week of age there were fewer reducible crosslinking amino acids (hydroxylysinonorleucine, dihydroxylysinonorleucine, and lysinonorleucine) in collagens from sternal cartilage and tendon in the scoliotic line than in the isogenic line. However, by week 3 and at weeks 5 or 7 values were similar in both groups. The amounts of hydroxypyridinium in vertebral bone and intervertebral disc collagen were also similar in both groups of birds. Consequently, differences in collagen crosslinking do not appear to be a persistent developmental defect underlying the expression of scoliosis in the model. However, differences were observed in cartilage proteoglycans and glycosaminoglycans from the scoliotic line that were not present in cartilage from the isogenic line. The average molecular weight of the uronide-containing glycosaminoglycans was 30% less in the scoliotic line than in the isogenic line, i.e., 12,000 compared to 18,000. The size distribution of cartilage proteoglycans from the scoliotic line also differed from that of proteoglycans from the isogenic line.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
9.
A series of fused and functionalized pyridine derivatives were designed, synthesized and tested for their potential antitubercular properties. All these novel compounds were prepared by using multistep methods involving the construction of pyridine ring as a key synthetic step. Some of these compounds were found to be interesting when tested for their antitubercular properties in vitro and one of them appeared as an attractive and potential antitubercular agent.  相似文献   
10.
This paper describes a novel antibody-based livestock movement control tool and method of meat allocation, both in livestock husbandry as well as during the meat-processing chain. Immuno Track fulfills diverse prerequisites and meets regulatory demands which are substantial for a successful monitoring technology: (i) the induction of long-lasting antibody responses detectable onsite throughout the whole mast period of pigs, (ii) a single immunization injection with protein derivatives is sufficient to evoke a strong epitope-specific antibody response, and (iii) the complete degradation of the protein markers after the antibody response has been triggered in meatproducing animals such as cattle or pigs. There are diverse fields of application for the Immuno-Track marker technology, such as in quality meat programs, as compliance markers for animal vaccines or as a tool for verification of origin. Combination of this monitoring technology with the husbandry and identification databases for cattle and pigs within the European Community will lead to greater transparency in meat production, thereby regaining consumers' trust in concomitant structures of the meat-producing industry.  相似文献   
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