The action of anticholinergic drugs on the oxidation of indole activated by acetylcholine chloride

Zusammenfassung Mittels Fluoreszenzmessung wurde die durch Acetylcholin aktivierte Indoloxydation verfolgt. Es wurde festgestellt, dass alle im Versuch verwendeten anticholinergischen Substanzen diese Reaktion konzentrationsabhängig abschwächen. Ist kein Aktivator vorhanden, verläuft die Indoloxydation äusserst langsam. Es wird angenommen, dass die anticholinergischen Substanzen die aktivierende Wirkung des Acetylcholins aufheben.     

Effect in heavy meromyosin on conformation of F-actin

Summary Cooperative conformational changes of F-actin induced by heavy meromyosin (HMM) binding (in the absence of troponin and tropomyosin) were found by the method of polarized UV-fluorescence microscopy.     

Molecular orbital studies on the conformation of γ-aminobutyric acid and muscimol

Zusammenfassung Mit Hilfe der Molecular Orbital Theorie werden die bevorzugten Konformationen für die-Aminobuttersäure und das strukturell verwandte Muscimol, die neurologisch bedeutsam sind, berechnet.

---

---

Supported by National Institutes of Health (US) Grant No. GM-16312.     

Are anticholinergic effects responsible for the heterogeneous quinidine-induced modifications of heart muscle refractoriness?

Cellular and Molecular Life Sciences - Vagal tone is responsible for the heterogeneous reactivity of atrial and ventricular contractile tissues to quinidine. Acetylcholine may make atrial cells...     

Natural peptide analgesics: the role of solution conformation

Endogenous opioids have been studied extensively since their discovery, in the hope of finding a perfect analgesic, devoid of the secondary effects of alkaloid opioids. However, the design of selective opioid agonists has proved very difficult. First, structural studies of peptides in general are hampered by their intrinsic flexibility. Second, the relationship between constitution and the so-called 'bioactive conformation' is far from obvious. Ideally, a direct structural study of the complex between a peptide and its receptor should answer both questions, but such a study is not possible, because opioid receptors are large membrane proteins, difficult to study by standard structural techniques. Thus, conformational studies of opioid peptides are still important for drug design and also for indirect receptor mapping. This review deals with conformational studies of natural opioid peptides in several solvents that mimic in part the different environments in which the peptides exert their action. None of the structural investigations yields a convincing bioactive conformation, but the global conformation of longer peptides in biomimetic environments can shed light on the interaction with receptors. Received 15 April 2001; received after revision 10 May 2001; accepted 11 May 2001     

On the relationship of hemoglobin oxidation with the conformation of hemoglobin

Summary The rate of hemoglobin oxidation by various oxidants was studied under aerobic and anaerobic conditions, and the mechanism of hemoglobin oxidation was discussed in relation to the conformation of hemoglobin.     

A study on the metabolism of some dienoic compounds

Riassunto Acidi dienoici marcati con¹⁴C facilmente aromatizzabili a fenoli per via chimica, sono stati somministrati a muffe produttrici di fenoli. Anzichè l'aromatizzazione è stata osservata una degradazione, che nel caso dell'acido 3-metilepta-2, 5-dien-1, 7-dioico conduce all'acido 2-metilglutarico.     

Spatial conformation of human serotransferrin glycans]

The construction of molecular models for the human serotransferrin glycans shows that they present one compact section linked to the protein and constituted by the pentasaccharide alpha-Man-(1 leads to 3)-[alpha-Man-(1 leads to 6)]-beta-Man-(1 leads to 4)-beta-GlcNAc-(1 leads to 4)-beta-GlcNAc-(1 leads to)-Asn to which are attached two "antennae" consisting of the trisaccharide alpha-NANA-(2 leads to 6)-beta-Gal-(1 leads to 4)-beta-GlcNAc. The trisaccharide sequence beta-Man-(1 leads to 4)-beta-GlcNAc-(1 leads to 4)-beta-GlcNAc adopts a flat and rigid conformation, stabilised by hydrogen bonds. In contrast, the sequence alpha-NANA-(1 leads to 6)-beta-Gal-(1 leads to 4)-beta-GlcNAc-(1 leads to 2)-alpha-Man takes up a helical configuration. The two "antennae" can be disposed on the pentasaccharide core to give two possible configurations, one Y-shaped and the other T-shaped. In both cases, the general conformation of the glycans is perfectly compatible with their postulated role as a recognition signal.     

The biologically active conformation of ergot alkaloids

Molecular mechanics and NMR studies of the D ring conformation of ergot alkaloids demonstrate that both D1 and D2 forms may exist in solution. The comparison of the geometric parameters defining the spatial relations between the aromatic moieties and the basic nitrogen of conformationally restricted dopamine analogs, and that of ergolene, shows the D1 conformation to be the bioactive one.     

The biologically active conformation of ergot alkaloids

Summary Molecular mechanics and NMR studies of the D ring conformation of ergot alkaloids demonstrate that both D₁ and D₂ forms may exist in solution. The comparison of the geometric parameters defining the spatial relations between the aromatic moieties and the basic nitrogen of conformationally restricted dopamine analogs, and that of ergolene, shows the D₁ conformation to be the bioactive one.     

The conformation of 4.5-substituted aporphine alkaloids

Résumé Par l'étude des rotations optiques, des spectres de l'ultraviolet, et des modèles moléculaires des alcaloides de l'aporphine, il a été démontré que dans les aporphines substituées en positions 4 et 5 le système biphényl est rigide et tordu.