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At least 541 records · Page 30Linked to original sources
PubMed1994

Identical amino acid sequence of ferredoxin from Datura metel and D. innoxia.

The complete amino acid sequence of the respective [2Fe-2S] ferredoxins from Datura metel (D. alba) and D. innoxia, have been determined by automated Edman degradation of the entire Cm-protein and of the peptides obtained by tryptic digestion and CNBr treatment. The ferredoxins from the two plants had an identical amino acid sequence, suggesting a very close taxonomic relationship between the two. This is the first report for the identical primary structure of Fds from different species of higher plants.

Amino Acid Sequence↗
PubMed1999

The metabolic effects of native and transgenic hemoglobins on plants.

The strictly aerobic bacterium Vitreoscilla expresses a hemoglobin-like protein, VHb, when subjected to oxygen stress. When expressed in plants, this has several intriguing physiological effects, such as improving the overall growth rate, speeding germination and flowering, and increasing the productivity of certain oxygen-requiring metabolic pathways. Although the mechanisms behind the effects of VHb in heterologous hosts are not yet fully characterized, it has been suggested that VHb facilitates oxygen transport and/or storage. This hypothesis is supported by the kinetic properties of VHb, which allow very rapid dissociation of oxygen from the protein.

Bacteria, Aerobic↗
PubMed1977

Jimson seed poisoning-- a new hallucinogen on the horizon.

Of 27 patients with Jimson seed poisoning recently treated in the University of Cincinnati Medical Center, 15 were admitted to the hospital, while 12 were treated and released. The patients ranged in age from 13 to 21. The dose was between 2 gm and 25 gm. Time from ingestion to arrival in the emergency department averaged 12.1 hours for those admitted and 10 hours for those who were not. All patients had altered mental status. Twenty-five of the 27 received Ipecac and all but one received at least 2 mg of physostigmine, which produced dramatic improvement in central nervous system symptoms. The authors have developed a management protocol based on physiologic criteria.

Adolescent↗
PubMed1999

Glutamine synthetase activity in Solanaceous cell suspensions accumulating alkaloids or not. 13C NMR and enzymatic assay.

The metabolism of labelled pyruvate followed by 13C NMR and the measure of glutamine synthetase (GS) showed, according to previous results, a high activity of this enzyme in suspension cells of Nicotiana plumbaginifolia. This activity could derive glutamate from the alkaloid synthesizing pathways. However, a recent work showed that the rate of the GS gene transcription was inversely proportional to the Gln/Glu ratio. The measures of Gln and Glu concentrations in Nicotiana plumbaginifolia cells revealed that high GS activity correlates with the weak value of Gln/Glu ratio. Therefore, the hypothesis of GS dysfunctioning for the non-biosynthesis of alkaloids in N. plumbaginifolia suspension cells can be discarded. This conclusion is strengthened by the results obtained when using a GS inhibitor.

Alkaloids↗
PubMed2003

Capturing enzyme structure prior to reaction initiation: tropinone reductase-II-substrate complexes.

To understand the catalytic mechanism of an enzyme, it is crucial to determine the crystallographic structures corresponding to the individual reaction steps. Here, we report two crystal structures of enzyme-substrate complexes prior to reaction initiation: tropinone reductase-II (TR-II)-NADPH and TR-II-NADPH-tropinone complexes, determined from the identical crystals. A combination of two kinetic crystallographic techniques, a continuous flow of the substrates and Laue diffraction measurements, enabled us to capture the transit structures prior to the reaction proceeding. A structure comparison of the enzyme-substrate complex elucidated in this study with the enzyme-product complex in our previous study indicates that one of the substrates, tropinone, is rotated relative to the product so as to make the spatial organization in the active site favorable for the reaction to proceed. Side chains of the residues in the active site also alter their conformations to keep the complementarity of the space for the substrate or the product and to assist the rotational movement.

Alcohol Oxidoreductases↗
PubMed1999

Structure of tropinone reductase-II complexed with NADP+ and pseudotropine at 1.9 A resolution: implication for stereospecific substrate binding and catalysis.

Tropinone reductase-II (TR-II) catalyzes the NADPH-dependent reduction of the carbonyl group of tropinone to a beta-hydroxyl group. The crystal structure of TR-II complexed with NADP+ and pseudotropine (psi-tropine) has been determined at 1.9 A resolution. A seven-residue peptide near the active site, disordered in the unliganded structure, is fixed in the ternary complex by participation of the cofactor and substrate binding. The psi-tropine molecule is bound in an orientation which satisfies the product configuration and the stereochemical arrangement toward the cofactor. The substrate binding site displays a complementarity to the bound substrate (psi-tropine) in its correct orientation. In addition, electrostatic interactions between the substrate and Glu156 seem to specify the binding position and orientation of the substrate. A comparison between the active sites in TR-II and TR-I shows that they provide different van der Waals surfaces and electrostatic features. These differences likely contribute to the correct binding mode of the substrates, which are in opposite orientations in TR-II and TR-I, and to different reaction stereospecificities. The active site structure in the TR-II ternary complex also suggests that the arrangement of the substrate, cofactor, and catalytic residues is stereoelectronically favorable for the reaction.

Alcohol Oxidoreductases↗
PubMed2002

Kinetic study of littorine rearrangement in Datura innoxia hairy roots by (13)C NMR spectroscopy.

The kinetics of tropane alkaloid biosynthesis, particularly the isomerization of littorine into hyoscyamine, were studied by analyzing the kinetics of carbon-13 ((13)C) in metabolites of Datura innoxia hairy root cultures fed with labeled tropoyl moiety precursors. Both littorine and hyoscyamine were the major alkaloids accumulated, while scopolamine was never detected. Feeding root cultures with (RS)-phenyl[1,3-(13)C(2)]lactic acid led to (13)C spin-spin coupling detected on C-1' and C-2' of the hyoscyamine skeleton, which validated the intramolecular rearrangement of littorine into hyoscyamine. Label from phenyl[1-(13)C]alanine or (RS)-phenyl[1,3-(13)C(2)]lactic acid was incorporated at higher levels in littorine than in hyoscyamine. Initially, the apparent hyoscyamine biosynthesized rate (v(app)()hyo = 0.9 micromol (13)C.flask(-1).d(-1)) was lower than littorine formation (v(app)()litto = 1.8 micromol (13)C.flask(-1).d(-1)), suggesting that the isomerization reaction could be rate limiting. The results obtained for the kinetics of littorine biosynthesis were in agreement with the role of this compound as a direct precursor of hyoscyamine biosynthesis.

Alkaloids↗
PubMed2002

Accidental mydriasis from exposure to Angel's trumpet (Datura suaveolens).

PURPOSE: To report clinical findings after accidental instillation into the eye of sap from Angel's trumpet (Datura suaveolens). METHODS: We report findings on seven patients who developed sudden onset of unilateral mydriasis. At least three of them also had ipsilateral cycloplegia and one developed transient tachycardia. RESULTS: The symptoms evolved after ocular exposure to sap from Angel's trumpet, a plant containing natural alkaloids with parasympatholytic properties. Six patients were initially unaware of the cause of their symptoms. In these cases, patient history revealed recent contact with Angel's trumpet. CONCLUSION: Accidental ocular instillation of sap from Angel's trumpet should be noted as a cause of sudden onset of mydriasis in otherwise unaffected patients and also of general symptoms like tachycardia.

Adult↗
PubMed1999

Angel trumpet lily poisoning in five adolescents: clinical findings and management.

OBJECTIVE: To describe clinical features and management of Angel trumpet lily poisoning in adolescents. METHODOLOGY: Case notes of five adolescent males who presented to the emergency department of a teaching hospital were reviewed. RESULTS: All five boys ingested a mixture of coca-cola and a brew prepared by boiling the leaves and flowers of the plant. They presented to the emergency department with various degrees of agitation and confusion and specific clinical signs. All were treated with charcoal and cathartics and discharged after 36 h. CONCLUSIONS: Due to its hallucinogenic effects, abuse of Angel trumpet lily is not uncommon and should be suspected in adolescents presenting with altered mental state and hallucinations in conjunction with other anticholinergic symptoms and signs.

Adolescent↗