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121.
The powder and tableting properties of cellulose II powders (MCCII) and (SDCII) were evaluated and compared with common direct compression binders. The cellulose II polymorphs offered more benefits in terms of functionality as compared with cellulose I (Avicel® PH-102) spray dried lactose and starch. Spray dried cellulose II (SDCII) had a better disintegrant ability, but a lower compactibility than microcrystalline cellulose I (Avicel® PH-102). However, when mixed and compressed with acetaminophen, SDCII was as compactable as cellulose I. Further, unprocessed cellulose II has a comparable compressibility to that of cellulose I. SDCII was found to be less friable, less sensitive to magnesium stearate, and possessed better acetaminophen loading capacity than unprocessed cellulose II and comparable to that of cellulose I. The cellulose II materials showed potential for use as a direct compression excipient. 相似文献
122.
Sun HG Ruszczycky MW Chang WC Thibodeaux CJ Liu HW 《The Journal of biological chemistry》2012,287(7):4602-4608
UDP-galactopyranose mutase (UGM) requires reduced FAD (FAD(red)) to catalyze the reversible interconversion of UDP-galactopyranose (UDP-Galp) and UDP-galactofuranose (UDP-Galf). Recent structural and mechanistic studies of UGM have provided evidence for the existence of an FAD-Galf/p adduct as an intermediate in the catalytic cycle. These findings are consistent with Lewis acid/base chemistry involving nucleophilic attack by N5 of FAD(red) at C1 of UDP-Galf/p. In this study, we employed a variety of FAD analogues to characterize the role of FAD(red) in the UGM catalytic cycle using positional isotope exchange (PIX) and linear free energy relationship studies. PIX studies indicated that UGM reconstituted with 5-deaza-FAD(red) is unable to catalyze PIX of the bridging C1-OP(β) oxygen of UDP-Galp, suggesting a direct role for the FAD(red) N5 atom in this process. In addition, analysis of kinetic linear free energy relationships of k(cat) versus the nucleophilicity of N5 of FAD(red) gave a slope of ρ = -2.4 ± 0.4. Together, these findings are most consistent with a chemical mechanism for UGM involving an S(N)2-type displacement of UDP from UDP-Galf/p by N5 of FAD(red). 相似文献
123.
Jung TY Li D Park JT Yoon SM Tran PL Oh BH Janeček Š Park SG Woo EJ Park KH 《The Journal of biological chemistry》2012,287(11):7979-7989
Staphylothermus marinus maltogenic amylase (SMMA) is a novel extreme thermophile maltogenic amylase with an optimal temperature of 100 °C, which hydrolyzes α-(1-4)-glycosyl linkages in cyclodextrins and in linear malto-oligosaccharides. This enzyme has a long N-terminal extension that is conserved among archaic hyperthermophilic amylases but is not found in other hydrolyzing enzymes from the glycoside hydrolase 13 family. The SMMA crystal structure revealed that the N-terminal extension forms an N' domain that is similar to carbohydrate-binding module 48, with the strand-loop-strand region forming a part of the substrate binding pocket with several aromatic residues, including Phe-95, Phe-96, and Tyr-99. A structural comparison with conventional cyclodextrin-hydrolyzing enzymes revealed a striking resemblance between the SMMA N' domain position and the dimeric N domain position in bacterial enzymes. This result suggests that extremophilic archaea that live at high temperatures may have adopted a novel domain arrangement that combines all of the substrate binding components within a monomeric subunit. The SMMA structure provides a molecular basis for the functional properties that are unique to hyperthermophile maltogenic amylases from archaea and that distinguish SMMA from moderate thermophilic or mesophilic bacterial enzymes. 相似文献
124.
Birgit Schiller Georgia Makrypidi Ebrahim Razzazi-Fazeli Katharina Paschinger Julia Walochnik Iain B. H. Wilson 《The Journal of biological chemistry》2012,287(52):43191-43204
Glycans play key roles in host-pathogen interactions; thus, knowing the N-glycomic repertoire of a pathogen can be helpful in deciphering its methods of establishing and sustaining a disease. Therefore, we sought to elucidate the glycomic potential of the facultative amoebal parasite Acanthamoeba. This is the first study of its asparagine-linked glycans, for which we applied biochemical tools and various approaches of mass spectrometry. An initial glycomic screen of eight strains from five genotypes of this human pathogen suggested, in addition to the common eukaryotic oligomannose structures, the presence of pentose and deoxyhexose residues on their N-glycans. A more detailed analysis was performed on the N-glycans of a genotype T11 strain (4RE); fractionation by HPLC and tandem mass spectrometric analyses indicated the presence of a novel mannosylfucosyl modification of the reducing terminal core as well as phosphorylation of mannose residues, methylation of hexose and various forms of pentosylation. The largest N-glycan in the 4RE strain contained two N-acetylhexosamine, thirteen hexose, one fucose, one methyl, and two pentose residues; however, in this and most other strains analyzed, glycans with compositions of Hex8–9HexNAc2Pnt0–1 tended to dominate in terms of abundance. Although no correlation between pathogenicity and N-glycan structure can be proposed, highly unusual structures in this facultative parasite can be found which are potential virulence factors or therapeutic targets. 相似文献
125.
Imamura A Yoshikawa T Komori T Ando M Ando H Wakao M Suda Y Ishida H Kiso M 《Glycoconjugate journal》2008,25(3):269-278
A series of ganglioside GM1-, GM2-, and GM3-type probes, in which the ceramide portion is replaced with a glucose residue,
were systematically synthesized based on a convergent synthetic method. 相似文献
126.
127.
Istvan Toth Pavla Simerska Yoshio Fujita 《International journal of peptide research and therapeutics》2008,14(4):333-340
Synthetic lipopeptide vaccines are being increasingly investigated mainly because of the advantages they offer over traditional
vaccines, including safety of use in humans, high specificity in eliciting immune responses, greater purity and large scale/cost-effective
production capacity. Moreover, a number of lipopeptide vaccines designed to possess self-adjuvanting properties have been
developed and tested in vitro and in vivo. Producing high levels of serum-specific antibodies against incorporated peptide
epitopes, they are showing their potential as effective vaccine candidates without the need for a co-administered adjuvant
and/or carrier protein, often associated with undesirable effects in humans. This review presents recent insights on lipopeptide
vaccine research and development, particularly on (1) the influence of the orientation of peptide epitopes and lipids on immune
responses, (2) the use of carbohydrates for vaccine targeting, adjuvanting or as peptide epitope carriers, and (3) synthetic
approaches to highly pure, multi-epitopic vaccine molecules using native chemical ligation techniques. Incorporation of different
types of antigens within the same lipopeptide construct could provide a lipopeptide vaccine candidate suitable for safe and
effective mucosal administration, which is a comfortable way of drug delivery. 相似文献
128.
129.
1H, 13C, and 15N backbone and side-chain chemical shift assignments for the 29 kDa human galectin-1 protein dimer 总被引:1,自引:0,他引:1
Irina V. Nesmelova Mabel Pang Linda G. Baum Kevin H. Mayo 《Biomolecular NMR assignments》2008,2(2):203-205
Galectin-1 is an important regulator of leukocyte function and tumor angiogenesis. Recently, this lectin has been identified
as a molecular target for the potent angiogenesis inhibitor anginex. Here, we report 1H, 13C, and 15N chemical shift assignments for human galectin-1 as determined by using heteronuclear triple resonance NMR spectroscopy. 相似文献
130.
Photobacterium damsela α2,6-sialyltransferase was cloned as N- and C- His-tagged fusion proteins with different lengths (16–497 aa or 113–497 aa). Expression and activity assays indicated that
the N-terminal 112 amino acid residues of the protein were not required for its α2,6-sialyltransferase activity. Among four truncated
forms tested, N-His-tagged Δ15Pd2,6ST(N) containing 16–497 amino acid residues had the highest expression level. Similar to the Δ15Pd2,6ST(N),
the shorter Δ112Pd2,6ST(N) was active in a wide pH range of 7.5–10.0. A divalent metal ion was not required for the sialyltransferase
activity, and the addition of EDTA and dithiothreitol did not affect the activity significantly.
Mingchi Sun and Yanhong Li contributed equally to this work. 相似文献