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961.
962.
The purpose of this reseach was to characterize and optimize the properties of microcapsules produced by the solvent exchange
method, a new microencapsulation technique. Reservoir-type microcapsules containing lysozyme as a model protein were produced
using a coaxial ultrasonic atomizer under various formulation and instrument settings, and characterized with respect to in
vitro release kinetics and stability of the encapsulated protein. The solvent exchange method could encapsulate protein drugs
with high efficiency under an optimized condition and was mild enough to preserve the integrity of the encapsulated lysozymes
during the process. In vitro release studies showed that the microcapsules could release proteins in a controllable manner.
The solvent exchange method is a mild and simple microencapsulation method that could encapsulate lysozyme, maintaining its
functional integrity. 相似文献
963.
964.
XAB2, a novel tetratricopeptide repeat protein involved in transcription-coupled DNA repair and transcription 总被引:6,自引:0,他引:6
965.
The type IV secretion system of Helicobacter pylori consists of 10--15 proteins responsible for transport of the transforming protein CagA into target epithelial cells. Secretion of CagA crucially depends on the hexameric ATPase, HP0525, a member of the VirB11-PulE family. We present the crystal structure of a binary complex of HP0525 bound to ADP. Each monomer consists of two domains formed by the N- and C-terminal halves of the sequence. ADP is bound at the interface between the two domains. In the hexamer, the N- and C-terminal domains form two rings, which together form a chamber open on one side and closed on the other. A model is proposed in which HP0525 functions as an inner membrane pore, the closure and opening of which is regulated by ATP binding and ADP release. 相似文献
966.
Upon sensing of peptide pheromone, Enterococcus faecalis efficiently transfers plasmid pCF10 through a type IV secretion (T4S) system to recipient cells. The PcfF accessory factor and PcfG relaxase initiate transfer by catalyzing strand-specific nicking at the pCF10 origin of transfer sequence (oriT). Here, we present evidence that PcfF and PcfG spatially coordinate docking of the pCF10 transfer intermediate with PcfC, a membrane-bound putative ATPase related to the coupling proteins of gram-negative T4S machines. PcfC and PcfG fractionated with the membrane and PcfF with the cytoplasm, yet all three proteins formed several punctate foci at the peripheries of pheromone-induced cells as monitored by immunofluorescence microscopy. A PcfC Walker A nucleoside triphosphate (NTP) binding site mutant (K156T) fractionated with the E. faecalis membrane and also formed foci, whereas PcfC deleted of its N-terminal putative transmembrane domain (PcfCDelta N103) distributed uniformly throughout the cytoplasm. Native PcfC and mutant proteins PcfCK156T and PcfCDelta N103 bound pCF10 but not pcfG or Delta oriT mutant plasmids as shown by transfer DNA immunoprecipitation, indicating that PcfC binds only the processed form of pCF10 in vivo. Finally, purified PcfCDelta N103 bound DNA substrates and interacted with purified PcfF and PcfG in vitro. Our findings support a model in which (i) PcfF recruits PcfG to oriT to catalyze T-strand nicking, (ii) PcfF and PcfG spatially position the relaxosome at the cell membrane to stimulate substrate docking with PcfC, and (iii) PcfC initiates substrate transfer through the pCF10 T4S channel by an NTP-dependent mechanism. 相似文献
967.
Studies of Ficus reproductive phenology have focused on documenting its seasonality and dependence on meteorological factors. While there
have been reports that duration of receptivity of syconia can be prolonged in response to pollinator limitation, the effect
of pollination rate on the duration of phenological phases over a year has not been examined. Percentage of unpollinated syconia,
number of foundresses per pollinated syconium, duration of receptivity, frequency of single-sex broods, crop size, frequency
of parasitisation, persistence of ripe syconia, and mass abscission were recorded for Ficus superba at the crop level. Percentage of unpollinated syconia is significantly negatively correlated with the number of foundresses
per syconium, and positively correlated with the duration of receptivity, and the persistence of ripe syconia. Despite the
absence of sesonality in reproduction, the occurrences of receptive syconia and ripe syconia showed unimodal and bimodal peaks,
respectively, owing to prolongment of these phases. This is attributable to meteorological factors, which are hypothesized
to influence pollinator dispersal, or population dynamics, and thus pollination rate. This highlights the overlooked significance
of pollinator, and possibly frugivore phenology in accounting for Ficus reproduction, and suggests that while reproduction may be aseasonal, reproductive potential may not be. Furthermore, crop
size was shown to affect the number of foundresses per syconium, duration of receptivity, and persistence of ripe syconia.
Possible adaptive value of producing crops of different sizes is discussed. 相似文献
968.
Young Ji Yoo Hanseong Kim Sung Ryeol Park Yeo Joon Yoon 《Journal of industrial microbiology & biotechnology》2017,44(4-5):537-553
Rapamycin is an immunosuppressive metabolite produced from several actinomycete species. Besides its immunosuppressive activity, rapamycin and its analogs have additional therapeutic potentials, including antifungal, antitumor, neuroprotective/neuroregenerative, and lifespan extension activities. The core structure of rapamycin is derived from (4R,5R)-4,5-dihydrocyclohex-1-ene-carboxylic acid that is extended by polyketide synthase. The resulting linear polyketide chain is cyclized by incorporating pipecolate and further decorated by post-PKS modification enzymes. Herein, we review the discovery and biological activities of rapamycin as well as its mechanism of action, mechanistic target, biosynthesis, and regulation. In addition, we introduce the many efforts directed at enhancing the production of rapamycin and generating diverse analogs and also explore future perspectives in rapamycin research. This review will also emphasize the remarkable pilot studies on the biosynthesis and production improvement of rapamycin by Dr. Demain, one of the world’s distinguished scientists in industrial microbiology and biotechnology. 相似文献
969.
Lay Teng Ang Antson Kiat Yee Tan Matias I. Autio Su Hua Goh Siew Hua Choo Kian Leong Lee Jianmin Tan Bangfen Pan Jane Jia Hui Lee Jen Jen Lum Christina Ying Yan Lim Isabelle Kai Xin Yeo Chloe Jin Yee Wong Min Liu Jueween Ling Li Oh Cheryl Pei Lynn Chia Chet Hong Loh Angela Chen Bing Lim 《Cell reports》2018,22(8):2190-2205
970.
Sang Hoon Yeo Jenna A. Monroy A. Kristopher Lappin Kiisa C. Nishikawa Dinesh K. Pai 《Journal of biomechanics》2013
We investigated the effectiveness of simple, Hill-type, phenomenological models of the force-length-velocity relationship for simulating measured length trajectories during muscle shortening, and, if so, what forms of the model are most useful. Using isotonic shortening data from mouse soleus and toad depressor mandibulae muscles, we showed that Hill-type models can indeed simulate the shortening trajectories with sufficiently good accuracy. However, we found that the standard form of the Hill-type muscle model, called the force-scaling model, is not a satisfactory choice. Instead, the results support the use of less frequently used models, the f-max scaling model and force-scaling with parallel spring, to simulate the shortening dynamics of muscle. 相似文献