Role of electrostatics in the binding of charged metallophthalocyanines to neutral and charged phospholipid membranes

Binding of the cationic tetra(tributylammoniomethyl)-substituted hydroxoaluminum phthalocyanine (AlPcN₄) to bilayer lipid membranes was studied by fluorescence correlation spectroscopy (FCS) and intramembrane field compensation (IFC) methods. With neutral phosphatidylcholine membranes, AlPcN₄ appeared to bind more effectively than the negatively charged tetrasulfonated aluminum phthalocyanine (AlPcS₄), which was attributed to the enhancement of the coordination interaction of aluminum with the phosphate moiety of phosphatidylcholine by the electric field created by positively charged groups of AlPcN₄. The inhibitory effect of fluoride ions on the membrane binding of both AlPcN₄ and AlPcS₄ supported the essential role of aluminum-phosphate coordination in the interaction of these phthalocyanines with phospholipids. The presence of negative or positive charges on the surface of lipid membranes modulated the binding of AlPcN₄ and AlPcS₄ in accord with the character (attraction or repulsion) of the electrostatic interaction, thus showing the significant contribution of the latter to the phthalocyanine adsorption on lipid bilayers. The data on the photodynamic activity of AlPcN₄ and AlPcS₄ as measured by sensitized photoinactivation of gramicidin channels in bilayer lipid membranes correlated well with the binding data obtained by FCS and IFC techniques. The reduced photodynamic activity of AlPcN₄ with neutral membranes violating this correlation was attributed to the concentration quenching of singlet excited states as proved by the data on the AlPcN₄ fluorescence quenching.     

In vitro binding to and in vivo effect on the cytosol and nuclear progesterone receptors of various progestins,and their relationship to synthesis of uteroglobin in rabbit uterus

In vitro binding affinities of various progestins to cytosol and nuclear progesterone receptors of rabbit uterus were determined and correlated with the biological potency of these steroids. In addition, cytosol and nuclear progesterone receptor levels were measured after a 5-day administration of different progestins (0.5 mg/kg daily) with variable biologic activites. The receptor levels were compared with the bilological response; the induction of uteroglobin synthesis. Cytosol and nuclear progesterone receptors had identical steroid binding properties (r = 0.98). The correlation between the in vitro binding affinity (cytosol or nuclear) and the in vivo biologic activity of the steroids was good (r = 0.73). After a 5-day treatment with progestins, the nuclear receptor concentration correlated in an inverse manner (r = ?0.84) with the uterine fluid unteroglobin concentration. A similar, but slightly weaker correlation (r = ?0.81) was also found for the cytosol receptor content and uteroglobin secretion. These data indicate that not only nuclear, but also cytosol progesterone receptor levels decrease in the rabbit uterus during chronic hormone action. Decline in the nuclear progesterone receptor content seemed to occur during treatment with all progestational steroids, while onlyi progestins with high biological potency were capable of decreasing the cytosol receptor content.     

The position of the epistatic S locus in the halothane linkage group in pigs

The linkage of the Phi, Pgd, Po2, S, H and halothane sensitivity loci was followed in a Belgian Landrace family, heterozygous for these systems over 6 generations. Recombination next to the S locus occurred mainly in pigs belonging to this particular family. From this investigation the position of the S locus is proved to be outwith the Phi-Pgd region, next to Phi . Therefore the gene sequence S - Phi - Hal -H- Po2 -Pgd is proposed. Higher recombination rates were observed in the female parental line of the multiheterozygous family when compared to the male parental line. Additional data from animals, unrelated to this strain, confirm the evidence of close linkage of the S system to the nearest marker loci.     

Selectivity is an Important Characteristic of Lipases (Acylglycerol Hydrolases)

Lipases are enzymes that usually hydrolyze acylglycerols, but will hydrolyze the carboxylic esters in many other compounds. They also catalyze esteriftcations and transesterifications. In addition to specificity for carboxylic esters, the lipases are selective for lipid classes and show selectivity for primary vs. secondary alcohols (positional or regio-), fatty acids, enantiomers (chirality of either the acid or alcohol residue) and combinations of these. Uses of the enzymes have depended to some extent on regio- and fatty acid selectivities. Newer applications, such as ester synthesis and asymmetric hydrolysis, may not be based on selectivities. Factors affecting selectivities are discussed and some areas for research are mentioned.     

Synthesis of phosphorylated 3,4-branched trisaccharides corresponding to LPS inner core structures of Neisseria meningitidis and Haemophilus influenzae

2-(N-Benzyloxycarbonyl)aminoethyl 7-O-acetyl-6-O-allyl-2-O-benzoyl-4-O-benzyl-3-O-chloroacetyl-l-glycero-α-d-manno-heptopyranosyl-(1→3)-[2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→4)]-6,7-di-O-acetyl-2-O-benzyl-l-glycero-α-d-manno-heptopyranoside, a spacer-equipped protected derivative of the common 3,4-branched diheptoside trisaccharide structure of the lipopolysaccharide core of Neisseria meningitidis and Haemophilus influenzae has been synthesized. The protecting group pattern installed allows regioselective introduction of phosphoethanolamine residues in the 3- and 6-position of the second heptose unit in accordance with native structures. From this intermediate the 3-and 6-monophosphoethanolamine as well as the non-phosphorylated deprotected trisaccharides have been synthesized to be used in evaluation of antibody binding specificity and in investigation of the substrate specificity of glycosyl transferases involved in the biosynthesis of LPS core structures.     

Iridoid glucosides in fouquieriaceae

From three Fouquieria sp. 12 iridoid glucosides were isolated and identified. Eight of these were structurally related to galioside (monotropein methylester), while four were hydroxy substitution products of deoxyloganin. In three cases the glucoside occurred together with the corresponding 10-O-acetate.     

TRIM32/USP11 Balances ARID1A Stability and the Oncogenic/Tumor-Suppressive Status of Squamous Cell Carcinoma

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Collagen biosynthesis by human skin fibroblasts III. The effects of ascorbic acid on procollagen production and prolyl hydroxylase activity

Human skin fibroblasts were cultured under conditions optimized for collagen synthesis, and the effects of ascorbic acid on procollagen production, proline hydroxylation and the activity of prolyl hydroxylase were examined in cultures. The results indicated that addition of ascorbic acid to confluent monolayer cultures of adult human skin fibroblasts markedly increased tha amount of [³H]hydroxyproline syntehsized. Ascorbic acid, however, did not increase the synthesis of ³H-labeled collagenous polypeptides assayed independently of hydroxylation of proline residues, nor did it affect the amount of prolyl hydroxylase detectable by an in vitro enzyme assay. Also long-term cultures of the cells or initiation of fibroblast cultures in the presence of ascorbic acid did not lead to an apparent selection of a cell population which might be abnormally responsive to ascorbic acid. Thus, ascorbic acid appears to have one primary action on the synthesis of procollagen by cultured human skin fibroblasts: it is necessary for synthesis of hydroxyproline, and consequently for proper triple helix formation and selection of procollagen.     

MODY 2: Mutation identification and molecular ancestry in a Brazilian family

Maturity Onset Diabetes of the Young (MODY) is a heterogeneous group of genetic diseases characterized by a primary defect in insulin secretion and hyperglycemia, non-ketotic disease, monogenic autosomal dominant mode of inheritance, age at onset less than 25 years, and lack of auto-antibodies. It accounts for 2–5% of all cases of non-type 1 diabetes. MODY subtype 2 is caused by mutations in the glucokinase (GCK) gene. In this study, we sequenced the GCK gene of two volunteers with clinical diagnosis for MODY2 and we were able to identify four mutations including one for a premature stop codon (c.76C>T). Based on these results, we have developed a specific PCR-RFLP assay to detect this mutation and tested 122 related volunteers from the same family. This mutation in the GCK gene was detected in 21 additional subjects who also had the clinical features of this genetic disease. In conclusion, we identified new GCK gene mutations in a Brazilian family of Italian descendance, with one due to a premature stop codon located in the second exon of the gene. We also developed a specific assay that is fast, cheap and reliable to detect this mutation. Finally, we built a molecular ancestry model based on our results for the migration of individuals carrying this genetic mutation from Northern Italy to Brazil.