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1.
The fungusAspergillus flavipes was grown on a Czapeck sucrose medium; the biomass so obtained was treated with high concentration of sucrose to release intracellular metabolites. Sephadex G-75 chromatography of the latter yielded a pure protein having anti-trypsin activity in vitro. 相似文献
2.
Sea snake (Microcephalophis gracilis) hemoglobin: Primary structure and relationships to other forms
The hemoglobin of the sea snakeMicrocephalophis gracilis was purified and the primary structure of the α and β chains determined. This is the first sea snake hemoglobin structure characterized, and apparently also the first complete structure of any snake hemoglobin (an α chain of a viper was known), allowing judgments of reptilian variants. Variations between the sea snake form and other reptilian forms are large (52–65 differences for the α chains), of similar order as those between the sea snake and avian (56–65 differences) or human (58 differences) forms. Functionally, 19 residues at α/β contact areas and 7 at heme contacts are exchanged in relation to the human α and β chains. Four positions of the sea snake hemoglobin contain residues thus far unique to this form. However, all replacements appear compatible with conserved overall functional properties. 相似文献
3.
Abstract: The pentameric subunit composition of a large population (36%) of the cerebellar granule cell GABAA receptors that show diazepam (or clonazepam)-insensitive [3 H]Ro 15-4513 binding has been determined by immunoprecipitation with subunit-specific antibodies. These receptors have α6 , α1 , γ2S , γ2L , and β2 or β3 subunits colocalizing in the same receptor complex. 相似文献
4.
Summary Petiolar felt-sheath of palm (Livistona chinensis) has been successfully used as a new biostructural matrix for the immobilization of fungal hyphae. The reticulated felt-sheath is made up of fibrous bundles having irregularly scattered membranous-foliose and fibrous outgrowths woven into a cohesive multi-layered mesh. Immobilization of Aspergillus niger was achieved with both spore and hyphal suspensions as the inoculum. Growth in immobilized cultures was 19% greater than in free cultures. 相似文献
5.
The role of polyamines (PA) synthesis in NMDA receptor-mediated45Ca2+ fluxes and norepinephrine release was studied in rat hippocampal synaptosomes. NMDA (50M) caused a sharp (>2-fold) transient increase in PA synthesis regulating enzyme, ornithine decarboxylase (ODC) activity with concomitant elevation in PA levels in the order putrescine>spermidine>spermine. ODC inhibitor, -difluoromethylornithine (DFMO), and NMDA antagonist, 2-amino-5-phosphonovaleric acid (D-AP5), both blocked increases in ODC activity and PA levels. Activation of NMDA receptors induced a sharp (3 to 4-fold) and quick (15 seconds) increase in45Ca2+ uptake by synaptosomes within 15 seconds of exposure at 37°C. The efflux of45Ca2+ and3H-norepinephrine (NE) release at 22°C from pre-loaded synaptosomes was also significantly (2 to 4-fold) enhanced by NMDA within 15 seconds. These NMDA receptor-mediated effects on calcium fluxes and NE release were blocked by NMDA receptor-antagonists (DAP-5 and MK-801) and PA synthesis inhibitor, DFMO and the DFMO inhibition nullified by exogenous putrescine. These observations establish that ODC/PA cascade play an important role in transduction of excitatory amino acid mediated signals at NMDA receptors.Special issue dedicated to Dr. Sidney Ochs. 相似文献
6.
Growth and extracellular polysaccharide production byPorphyridium cruentum were measured as a function of several culture parameters. Photon flux density of 75 μmol m−2 s−1 and CO2 concentration of 2.5% were found to be optimum for both growth and extracellular polysaccharide production. Interactive studies
on these two parameters further confirmed that at these levels of photon flux density and CO2, when applied together, both growth (5.9·107 cells per mL) and extracellular polysaccharide production (1.9 g/L) were at the maximum. Maximum growth and extracellular
polysaccharide production were observed at inoculum density of 106 cells per mL and aeration rate of 500 mL air per min per liter. 相似文献
7.
Zafar R. S. Weber R. E. Sharma P. K. Vinogradov S. N. Walz D. A. 《Protein expression and purification》1993,4(6)
The apoprotein of component P1 of the polymeric fraction of the intracellular hemoglobin of the marine polychaete Glycera dibranchiata has been expressed at a high level in Escherichia coli. The expressed globin was reconstituted with heme and purified. The N-terminal sequence of the recombinant P1 is identical to the cDNA-derived sequence of cloned P1 (Zafar et al., Biochem. Biophys. Acta, 1041, 117-123, 1990). Gel filtration, SDS-PAGE, optical spectra over the range 200-650 nm, and circular dichroism over the range 200-250 nm of the purified recombinant P1 were very similar to the polymeric fraction of native Glycera hemoglobin. The molar ellipticity at 222 nm provided an estimate of 77% for the α-helical content of the recombinant P1, in excellent agreement with that calculated from the crystal structure of Glycera monomeric component M-II. Although the oxygen binding affinity of the recombinant P1 is higher than that of the polymeric fraction of Glycera hemoglobin (3-4 torr vs 7-13 torr), which consists of at least six different single-chain hemoglobins, the Hill coefficient is lower (1.0-1.2 vs 1.2-1.4). 相似文献
8.
Molecular and Cellular Biochemistry - The excitatory amino acids (EAA), L-glutamate and L-aspartate were initially advanced as excitatory neurotransmitters some 30 years ago but in the past few... 相似文献
9.
Calmodulin, a calcium-dependent regulatory protein has been isolated from mammalian nerve. The protein has similarities to the calcium-binding protein earlier shown to be transported at a fast rate in the nerve fibers. The implication is that calmodulin, which has been shown to be involved in various key cellular processes, may have a relation to axoplasmic transport. 相似文献