A 42-kD, calcium-dependent, membrane-binding protein (VCaB42) was associated with partially purified vacuole membranes. Membrane-dissociation assays indicated that VCaB42 binding to vacuole membranes was selective for calcium over other cations and that 50% of VCaB42 remained membrane bound at 61 2 11 nM free calcium. A 13-amino acid sequence obtained from VCaB42 showed 85% similarity with the endonexin fold, a sequence found in the annexin family of proteins that is thought to be essential for calcium and lipid binding. The greatest similarity in amino acid sequence was observed with annexin Vlll (VAC-0). The calcium-binding properties and sequence similarities suggest that VCaB42 is a member of the annexin family of calciumdependent, membrane-binding proteins. Functional assays for VCaB42 on vacuole membrane transport processes indicated that it did not significantly affect the initial rate of calcium uptake into vacuole membrane vesicles. Because VCaB42 is vacuole localized (likely on the cytosolic surface of the vacuole) and is 50% dissociated within the physiological range of cytosolic free calcium, we hypothesize that this protein is a sensor that monitors cytosolic calcium levels and transmits that information to the vacuole.
Transoesophageal echocardiography can be performed on an outpatient basis in children with a wide spectrum of congenital cardiac malformations, and propofol is an ideal sedative agent in this setting. Although not common, preparations must be made for significant haemodynamic and respiratory complications. In our study, we intubated all the children under 2 years of age.
Disclosed herein is a photoinduced selective hydroamination of ynamides with nitrogen heteroaromatic nucleophiles. By using an organocatalytic photoredox system, a direct method to construct a diverse of (Z)‐α‐azole enamides from ynamides and pyrazoles, as well as triazoles, benzotriazoles, indazoles, and tetrazoles, is developed, thus providing a photocatalytically synthetic route to heterocyclic motifs common in medicinal agents. Based on the mechanistic studies, the hydroamination is postulated to operate via a mechanism in which the single‐electron oxidation of ynamide and the intermediacy of an alkyne radical cation, is responsible for the observed reactivity.
Disclosed herein is a novel photoinduced selective hydroamination of ynamides with nitrogen heteroaromatic nucleophiles. By using an organocatalytic photoredox system, a direct method to construct a diverse of (Z)-α-azole enamides from ynamides and pyrazoles, as well as triazoles, benzotriazoles, indazoles, and tetrazoles, is developed, thus providing a concise route to heterocyclic motifs common in medicinal agents. Based on the mechanistic studies, the hydroamination is postulated to operate via a mechanism in which the single-electron oxidation of ynamide and the intermediacy of an alkyne radical cation, is responsible for the observed reactivity.
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