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1.
2.
J H Fellman 《Journal of neurochemistry》1969,16(2):135-143
Abstract— 1. A chemical method for the determination of acetylcholine has been devised based upon (a) The precipitation of acetylcholine out of solution as an iodine complex. (b) The absorption of the quaternary ester to a ‘carboxyl’ ion exchange resin column. (c) The hydrazinolysis of the acetylcholine to form acetyl hydrazide. (d) The formation of a fluorescent molecule with salicylaldehyde. 2. The method was utilized to determine (a) If tetramethylammonium ions would release acetylcholine from the cat cervical synaptic ganglion. (b) The activity of enzyme choline acetyltransferase in rat brain. 3. The observation that tetramethylammonium ions do release acetylcholine sustains the viability of the hypothesis that acetylcholine forms a primary acyl bond with its receptor. 相似文献
3.
We have shown previously that anti-phenylphosphocholine antibodies elicited by phosphocholine-keyhole limpet hemocyanin can be divided into two populations according to their ability to recognize the two hapten analogues p-nitrophenylphosphocholine (NPPC) and p-nitrophenyl 3,3-dimethylbutyl phosphate (NPDBP). These analogues differ from each other in that NPPC has a positively charged nitrogen in the choline moiety, whereas NPDBP lacks the positively charged nitrogen. Group II-A antibodies bind only NPPC, whereas group II-B antibodies bind both ligands. Here, by infrared and nuclear magnetic resonance spectroscopic investigations, we find that when free in solution NPPC has a predominantly fixed structure in which the termini approach each other, probably due to electrostatic interactions within the molecule; this "bent" structural feature is retained when the ligand is bound by antibody. In contrast, the structure of unbound NPDBP is less fixed, being characterized by rapidly interchanging conformations corresponding to an open chain structure with less overall proximity of the termini compared to NPPC. The overall shape of NPPC is essentially unaltered by binding, whereas in the case of NPDBP what was a minor conformation in the unbound state becomes the predominate conformation of the bound ligand. Thus, our results are consistent with these antibodies providing a molecular template for stabilizing the conformation of the bound ligand. 相似文献
4.
Esmaeil Fallahi Brenda R. Simons John K. Fellman W. Michael Colt 《Plant Growth Regulation》1992,11(4):435-439
Effects of various concentrations of Dormex (a.i. 49% hydrogen cyanamide) on fruit thinning of Rome Beauty apple (Malus domestica Borkh.), Friar and Simka plums (Prunus salicina Lindley) were studied. A full bloom application of Dormex at all tested concentrations decreased Rome Beauty apple fruit set and yield, and increased fruit weight. Dormex at 0.25% (v/v) resulted in adequate apple thinning, indicated by production of an optimum fruit weight (320 g). Prebloom and full bloom applications of Dormex at greater than 0.75% reduced plum fruit set and yield in Friar. Full bloom application of Dormex at 0.50% showed a satisfactory fruit set, yield, and fruit weight in Friar plum. Prebloom Dormex application had no significant effect on `Simka' plum fruit set or yield, but full bloom application decreased fruit set and yield. 相似文献
5.
Antioxidant role and subcellular location of hypotaurine and taurine in human neutrophils. 总被引:3,自引:0,他引:3
The subcellular location of taurine, and its precursor, hypotaurine, within human neutrophils has been examined by nitrogen cavitation, Percoll-gradient centrifugation and HPLC analysis. Hypotaurine and taurine were found to reside within the cytosolic compartment of the cell. The ratio of taurine to hypotaurine is approx 50:1. The cytosolic concentration of taurine is approx. 50 mM. The concentration of hypotaurine decreased by 80% when resting neutrophils were converted into actively respiring cells by exposure to opsonized zymosan. These results prompted in vitro studies on the antioxidant properties of hypotaurine. We demonstrate by EPR spectroscopy that hypotaurine competes with 5,5'-dimethyl-1-pyrroline N-oxide) (DMPO) for hydroxyl radicals, and that it is the sulfinyl group which confers hydroxyl radical scavenging activity to it. Following its exposure to hydroxyl radicals, two oxidation products were isolated by HPLC, one of which has been identified as taurine. The biological roles of hypotaurine and taurine in the neutrophil are discussed with respect to their antioxidant properties and subcellular location within the cell. 相似文献
6.
We report that mammalian tissues posses hypotaurine (2-aminoethane- sulfinate) aminotransferase activity. One product of transamination, sulfinoacetaldehyde could theoretically undergo internal oxidation-reduction leading to isethionate (2-hydroxyethanesulfonate). This hypothesis was examined. No isethionate was formed . 相似文献
7.
G H Wada J H Fellman T S Fujita E S Roth 《The Journal of biological chemistry》1975,250(17):6720-6726
Avian liver p-hydroxyphenylpyruvate hydroxylase (EC 1.13.11.27) was purified to a 1000-fold increase in specific activity over crude supernatant, utilizing a substrate analogue, o-hydroxyphenylpyruvate, to stabilize the enzyme. The preparation was homogeneous with respect to sedimentation with a sedimentation velocity (s20,w) of 5.3 S. The molecular weight of the enzyme was determined to be 97,000 +/- 5,000 by sedimentation equilibrium, and the molecular weight of the subunits was determined to be 49,000 +/- 3,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Polyacrylamide gel electrophoresis revealed heterogeneity of the purified enzyme. The multiple molecular forms were separable by isoelectric focusing, and their isoelectric points ranged from pH 6.8 to 6.0. The amino acid compositions and tryptic peptide maps of the three forms isolated by isoelectric focusing were very similar. The forms of the enzyme had the same relative activity toward p-hydroxyphenylpyruvate and phenylpyruvate. Conditions which are known to accelerate nonenzymic deamidation of proteins caused interconversion of the multiple molecular forms. Iron was the only transition metal found to be associated with the purified enzyme at significant levels. The amount of enzyme-bound iron present in equilibrium-dialyzed samples was equivalent to 1 atom of iron per enzyme subunit. Purification of the enzyme activity correlated with the purification of the enzyme-bound iron. An EPR scan of the purified enzyme gave a signal at g equal 4.33, which is characteristic of ferric iron in a rhombic ligand field. 相似文献
8.
William J. Sutherland Rosalind Aveling Thomas M. Brooks Mick Clout Lynn V. Dicks Liz Fellman Erica Fleishman David W. Gibbons Brandon Keim Fiona Lickorish Kathryn A. Monk Diana Mortimer Lloyd S. Peck Jules Pretty Johan Rockström Jon Paul Rodríguez Rebecca K. Smith Mark D. Spalding Femke H. Tonneijck Andrew R. Watkinson 《Trends in ecology & evolution》2014
9.
Ryan M. Burrows Jason B. Fellman Regina H. Magierowski Leon A. Barmuta 《Hydrobiologia》2013,703(1):1-14
Clearfell, burn and sow (CBS) forestry can potentially alter stream environments by increasing available light and the input of woody debris. However, little is known about how CBS forestry affects in-stream processes such as nutrient uptake. We evaluate whether short-term (2–7 years) environmental changes (e.g. light availability and woody debris) associated with CBS forestry lead to differences in nutrient uptake metrics. To do this, we measured in-stream uptake of soluble reactive phosphorus (SRP) and ammonium (NH4) in three old growth (OG) and four CBS-affected headwater stream reaches. The abundance of fine woody debris and light availability were significantly greater in CBS-affected than in OG reaches. Uptake velocities varied from 0.0880 to 0.951 mm min?1 for NH4 and from 0.0383 to 1.06 mm min?1 for SRP across all sites. The mean uptake of SRP, but not NH4, was significantly greater (i.e. higher uptake velocities and lower uptake lengths) in CBS-affected than in OG reaches. These results suggest that CBS forestry altered the stream environment enabling greater SRP uptake relative to OG reaches. Our findings highlight the tight linkage between headwater streams and their surrounding terrestrial environment, which has direct implications for catchment-scale biogeochemical processes. 相似文献
10.
Visapää I Fellman V Vesa J Dasvarma A Hutton JL Kumar V Payne GS Makarow M Van Coster R Taylor RW Turnbull DM Suomalainen A Peltonen L 《American journal of human genetics》2002,71(4):863-876
GRACILE (growth retardation, aminoaciduria, cholestasis, iron overload, lactacidosis, and early death) syndrome is a recessively inherited lethal disease characterized by fetal growth retardation, lactic acidosis, aminoaciduria, cholestasis, and abnormalities in iron metabolism. We previously localized the causative gene to a 1.5-cM region on chromosome 2q33-37. In the present study, we report the molecular defect causing this metabolic disorder, by identifying a homozygous missense mutation that results in an S78G amino acid change in the BCS1L gene in Finnish patients with GRACILE syndrome, as well as five different mutations in three British infants. BCS1L, a mitochondrial inner-membrane protein, is a chaperone necessary for the assembly of mitochondrial respiratory chain complex III. Pulse-chase experiments performed in COS-1 cells indicated that the S78G amino acid change results in instability of the polypeptide, and yeast complementation studies revealed a functional defect in the mutated BCS1L protein. Four different mutations in the BCS1L gene have been reported elsewhere, in Turkish patients with a distinctly different phenotype. Interestingly, the British and Turkish patients had complex III deficiency, whereas in the Finnish patients with GRACILE syndrome complex III activity was within the normal range, implying that BCS1L has another cellular function that is uncharacterized but essential and is putatively involved in iron metabolism. 相似文献