beta-N-acetylhexosaminidase isoenzymes during chick embryo development

1. Two forms (I and II) with acidic pH optima and a neutral form of beta-hexosaminidase has been separated by DEAE-cellulose chromatography and characterized in skin and lung of 7, 9, 11, 14 day chick embryos and 1 day old chicken. 2. Forms I and II are similar to hexosaminidase A and B for their behaviour on DEAE-cellulose chromatography, Concanavalin A-Sepharose column and thermal stability. 3. Neutral form has a neutral pH optimum and higher molecular weight and a more acidic I. P. than forms I and II, a low beta-N-acetylgalactosaminidase activity and it is not bound by a Concanavalin A-Sepharose column and in that resemble hexosaminidase C and/or other neutral hexosaminidases. 4. We have found differences in the percentage of neutral form and in the specific activities of the extracts in the skin in different stages of development. 5. No significant differences were observed in the lung.     

Simple and high yield synthesis of (±)10,10′-dimethyl-dotriacontan-1,1′-diol as a building block for branched bola compounds. Preparation of (±)10,10′-dimethyl-dotriaconta-1,1′-diyl-bis[2-(trimethylammonio)ethyl phosphate] and the corresponding unbranched equivalent

The synthesis of a specially methyl branched bipolar hydrocarbon chain is described by alkylation of 1,12-dibromododecane with two equivalents of the dianion of undec-10-enoic acid. The subsequent transformation includes the reduction of the carboxyl groups to methyl branches and the hydroboration of the terminal olefines. The resulting 1,32 diol is suitable for phosphorylation in order to form the corresponding 1,1′bis-phosphocholine.     

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Different binding modes of tropeines mediating inhibition and potentiation of α1 glycine receptors

Tropeines are bidirectional modulators of native and recombinant glycine receptors (GlyRs) and promising leads for the development of novel modulatory agents. Tropisetron potentiates and inhibits agonist-triggered GlyR currents at femto- to nanomolar and micromolar concentrations respectively. Here, the potentiating and inhibitory effects of another tropeine, 3α-(3'-methoxy-benzoyloxy)nortropane (MBN) were examined by voltage-clamp electrophysiology at wild type and mutant α1 GlyRs expressed in Xenopus laevis oocytes. Several substitutions around the agonist-binding cavity of the α1 subunit interface (N46C, F63A, N102A, R119K, R131A, E157C, K200A, Y202L and F207A) were found to reduce or eliminate MBN inhibition of glycine activation. In contrast, the binding site mutations Q67A, R119A and S129A which did not affect MBN inhibition abolished the potentiation of chloride currents elicited by low concentrations of the partial agonist taurine following pre-incubation with MBN. Thus, potentiation and inhibition involve distinct binding modes of MBN in the inter-subunit agonist-binding pocket of α1 GlyRs. Homology modelling and molecular dynamics simulations disclosed two distinct docking modes for MBN, which are consistent with the differential effects of individual binding site substitutions on MBN inhibition and potentiation respectively. Together these results suggest that distinct binding modes at adjacent binding sites located within the agonist-binding pocket of the GlyR mediate the bidirectional modulatory effects of tropeines.     

Structural elucidation of 13-acetoxylichesterinic and 13-acetoxyprotolichesterinic acids,two aliphatic lichen metabolites from Neuropogon trachycarpus

From the lichen Neuropogon trachycarpus, six aliphatic acids related to lichesterinic acid have been isolated: neuropogolic, murolic, isomuronic an     

Restoration of a normal phenotype, microtubular pattern and DNA synthesis in embryonic fibroblasts concanavalin A pretreated

The present research investigated the time required for reconstructing normal microtubular pattern and the phenotype of cells after short-term (30 min.) and long-term (24 hrs.) pretreatment with the lectin concanavalin A (Con A). Short-term pretreatment led to the formation of incomplete tubules within 2 and 24 hrs. in cells cultured in 199 medium alone. The addition of serum to the medium reversed the globular phenotype and allowed the formation of normal microtubules, even after prolonged pretreatment with Con A. Whereas long-term Con A treatment provoked a reduction in DNA synthesis in 199 alone, in serum-added 199 the percentage of 3H-thymidine incorporation of treated cells tended to reach that of controls over time.