Influence of selected auxiliary substances on some physicochemical properties of solid dispersions containing magnesium salts.
(33/166)
In this survey magnesium sails in the form of solid dispersions were studied to examine the interaction of the drug and lecithin or Tego Betain L-7. The results of thermal analysis of solid dispersions containing magnesium adipate Mg[Adip] and compounds of this salt with glycine substituent, and the partition coefficient (logP) of this salts applied for solid dispersion, have been presented in this paper. Lecithin (45% phosphatidylcholine) or Tego Betain L-7 (30% solution of amide betaine) have been added to magnesium salts to obtain a solid dispersion. The influence of auxiliary substances: Tego Betain L-7 and lecithin on physicochemical properties of the examined preparations has been assessed. The results of thermal analysis (DTA, DSC, TG) of magnesium complexes indicated their good thermal resistance up to the temperature of 375 K. (+info)
Characterization of the genes encoding beta-ketoadipate: succinyl-coenzyme A transferase in Pseudomonas putida.
(34/166)
beta-Ketoadipate:succinyl-coenzyme A transferase (beta-ketoadipate:succinyl-CoA transferase) (EC 2.8.3.6) carries out the penultimate step in the conversion of benzoate and 4-hydroxybenzoate to tricarboxylic acid cycle intermediates in bacteria utilizing the beta-ketoadipate pathway. This report describes the characterization of a DNA fragment from Pseudomonas putida that encodes this enzyme. The fragment complemented mutants defective in the synthesis of the CoA transferase, and two proteins of sizes appropriate to encode the two nonidentical subunits of the enzyme were produced in Escherichia coli when the fragment was placed under the control of a phage T7 promoter. DNA sequence analysis revealed two open reading frames, designated pcaI and pcaJ, that were separated by 8 bp, suggesting that they may comprise an operon. A comparison of the deduced amino acid sequence of the P. putida CoA transferase genes with the sequences of two other bacterial CoA transferases and that of succinyl-CoA:3-ketoacid CoA transferase from pig heart suggests that the homodimeric structure of the mammalian enzyme may have resulted from a gene fusion of the bacterial alpha and beta subunit genes during evolution. Conserved functional groups important to the catalytic activity of CoA transferases were also identified. (+info)
The fluorene catabolic linear plasmid in Terrabacter sp. strain DBF63 carries the beta-ketoadipate pathway genes, pcaRHGBDCFIJ, also found in proteobacteria.
(35/166)
Terrabacter sp. strain DBF63 is capable of degrading fluorene (FN) to tricarboxylic acid cycle intermediates via phthalate and protocatechuate. Genes were identified for the protocatechuate branch of the beta-ketoadipate pathway (pcaR, pcaHGBDCFIJ) by sequence analysis of a 70 kb DNA region of the FN-catabolic linear plasmid pDBF1. RT-PCR analysis of RNA from DBF63 cells grown with FN, dibenzofuran, and protocatechuate indicated that the pcaHGBDCFIJ operon was expressed during both FN and protocatechuate degradation in strain DBF63. The gene encoding beta-ketoadipate enol-lactone hydrolase (pcaD) was not fused to the next gene, which encodes gamma-carboxymuconolactone decarboxylase (pcaC), in strain DBF63, even though the presence of the pcaL gene (the fusion of pcaD and pcaC) within a pca gene cluster has been thought to be a Gram-positive trait. Quantitative RT-PCR analysis revealed that pcaD mRNA levels increased sharply in response to protocatechuate, and a biotransformation experiment with cis,cis-muconate using Escherichia coli carrying both catBC and pcaD indicated that PcaD exhibited beta-ketoadipate enol-lactone hydrolase activity. The location of the pca gene cluster on the linear plasmid, and the insertion sequences around the pca gene cluster suggest that the ecologically important beta-ketoadipate pathway genes, usually located chromosomally, may be spread widely among bacterial species via horizontal transfer or transposition events. (+info)
Effects of perinatal exposure to phthalate/adipate esters on hypothalamic gene expression and sexual behavior in rats.
(36/166)
Our previous research has identified the granulin (grn) and p130 genes as sex steroid-regulated genes in the neonatal rat hypothalamus that might be involved in sexual differentiation of the brain. Since phthalate/adipate esters such as di-n-butyl phthalate (DBP), diisononyl phthalate (DINP), and di-2-ethylhexyl adipate (DEHA) are suspected to interfere with the endocrine system as environmental endocrine disruptors having estrogenic or antiandrogenic properties, these chemicals may affect sexual differentiation of the brain. The present study assessed the effects of perinatal exposure to DBP, DINP, and DEHA on grn and p130 mRNA expressions in the hypothalamus on postnatal day (PND) 7 and sexual behaviors after maturation in rats. Maternal rats were given a phytoestrogen-free diet containing different doses of DBP (20, 200, 2,000, and 10,000 ppm), DINP (40, 400, 4,000, and 20,000 ppm) and DEHA (480, 2,400, and 12,000 ppm) from gestational day 15 to the day of weaning (PND 21). DBP and DINP exposure during the perinatal period resulted in an increase in hypothalamic grn and p130 mRNA levels in females and males, respectively, but DEHA exposure decreased expression levels of grn in males and p130 in females, although the effects were not dose-dependent. After maturation, male rats that were exposed to several doses of DBP, DINP, and DEHA displayed decreased copulatory behavior. The lordosis quotient was decreased in females perinatally exposed to DBP, DINP, and DEHA at all the doses used. On the other hand, serum levels of LH and FSH in both sexes and the estrous cycles in females were not affected by the treatments. These results suggest that inappropriate expression of grn and/or p130 genes in the brains of male and female neonatal rats by perinatal exposure to these chemicals may exert permanent effects on the hypothalamus, thereby decreasing sexual behavior after maturation. (+info)
Aerobic benzoyl-coenzyme A (CoA) catabolic pathway in Azoarcus evansii: conversion of ring cleavage product by 3,4-dehydroadipyl-CoA semialdehyde dehydrogenase.
(37/166)
Benzoate, a strategic intermediate in aerobic aromatic metabolism, is metabolized in various bacteria via an unorthodox pathway. The intermediates of this pathway are coenzyme A (CoA) thioesters throughout, and ring cleavage is nonoxygenolytic. The fate of the ring cleavage product 3,4-dehydroadipyl-CoA semialdehyde was studied in the beta-proteobacterium Azoarcus evansii. Cell extracts contained a benzoate-induced, NADP(+)-specific aldehyde dehydrogenase, which oxidized this intermediate. A postulated putative long-chain aldehyde dehydrogenase gene, which might encode this new enzyme, is located on a cluster of genes encoding enzymes and a transport system required for aerobic benzoate oxidation. The gene was expressed in Escherichia coli, and the maltose-binding protein-tagged enzyme was purified and studied. It is a homodimer composed of 54 kDa (without tag) subunits and was confirmed to be the desired 3,4-dehydroadipyl-CoA semialdehyde dehydrogenase. The reaction product was identified by nuclear magnetic resonance spectroscopy as the corresponding acid 3,4-dehydroadipyl-CoA. Hence, the intermediates of aerobic benzoyl-CoA catabolic pathway recognized so far are benzoyl-CoA; 2,3-dihydro-2,3-dihydroxybenzoyl-CoA; 3,4-dehydroadipyl-CoA semialdehyde plus formate; and 3,4-dehydroadipyl-CoA. The further metabolism is thought to lead to 3-oxoadipyl-CoA, the intermediate at which the conventional and the unorthodox pathways merge. (+info)
Novel hydrophobic surface binding protein, HsbA, produced by Aspergillus oryzae.
(38/166)
Hydrophobic surface binding protein A (HsbA) is a secreted protein (14.5 kDa) isolated from the culture broth of Aspergillus oryzae RIB40 grown in a medium containing polybutylene succinate-co-adipate (PBSA) as a sole carbon source. We purified HsbA from the culture broth and determined its N-terminal amino acid sequence. We found a DNA sequence encoding a protein whose N terminus matched that of purified HsbA in the A. ozyzae genomic sequence. We cloned the hsbA genomic DNA and cDNA from A. oryzae and constructed a recombinant A. oryzae strain highly expressing hsbA. Orthologues of HsbA were present in animal pathogenic and entomopathogenic fungi. Heterologously synthesized HsbA was purified and biochemically characterized. Although the HsbA amino acid sequence suggests that HsbA may be hydrophilic, HsbA adsorbed to hydrophobic PBSA surfaces in the presence of NaCl or CaCl(2). When HsbA was adsorbed on the hydrophobic PBSA surfaces, it promoted PBSA degradation via the CutL1 polyesterase. CutL1 interacts directly with HsbA attached to the hydrophobic QCM electrode surface. These results suggest that when HsbA is adsorbed onto the PBSA surface, it recruits CutL1, and that when CutL1 is accumulated on the PBSA surface, it stimulates PBSA degradation. We previously reported that when the A. oryzae hydrophobin RolA is bound to PBSA surfaces, it too specifically recruits CutL1. Since HsbA is not a hydrophobin, A. oryzae may use several types of proteins to recruit lytic enzymes to the surface of hydrophobic solid materials and promote their degradation. (+info)
Fungal colonization of soil-buried plasticized polyvinyl chloride (pPVC) and the impact of incorporated biocides.
(39/166)
Plasticized polyvinyl chloride (pPVC) with or without incorporated biocides was buried in grassland and forest soil for up to 10 months. The change with time in viable counts of fungi on the plastic surface was followed, together with the percentage capable of clearing the two plasticizers dioctyl adipate (DOA) and dioctyl phthalate (DOP). With time fungal total viable counts (TVC) on control pPVC increased and the fraction able to clear DOA was considerably higher than the average estimated in both soil types. A total of 92 fungal morphotypes were isolated from grassland soil and 42 from forest soil with the greatest variety of fungal isolates observed on control pPVC. The incorporation of biocides into pPVC affected both fungal TVC and the richness of species isolated. The biocides NCMP [n-(trichloromethylthio)phthalimide], OBPA (10,10'-oxybisphenoxarsine) and OIT (2-n-octyl-4-isothiazolin-3-one) were the most effective in grassland soil, and TCMP [2,3,5,6-tetrachloro-4-(methylsulphonyl)pyridine] and NCMP the most effective in forest soil. In grassland soil, Penicillium janthinellum established as a principal colonizer and was recovered from all pPVC types. DOP clearers were found at much lower levels than DOA clearers, with Doratomyces spp. being the most efficient. At the end of 10 months the physical properties of the pPVC were altered; changes in stiffness were the most significant for heavily colonized grassland-buried pPVC samples, whereas in forest soil, the extensibility of the pPVC was affected more than the stiffness. These results suggest that fungi are important colonizers of pPVC buried in soil and that enrichment of soil fungi capable of clearing DOA occurs during colonization of the plastic surface. The results also demonstrate that incorporated biocides have a marked impact on the richness of species colonizing the pPVC surface. (+info)
Characterization of the beta-ketoadipate pathway in Sinorhizobium meliloti.
(40/166)
Aromatic compounds represent an important source of energy for soil-dwelling organisms. The beta-ketoadipate pathway is a key metabolic pathway involved in the catabolism of the aromatic compounds protocatechuate and catechol, and here we show through enzymatic analysis and mutant analysis that genes required for growth and catabolism of protocatechuate in the soil-dwelling bacterium Sinorhizobium meliloti are organized on the pSymB megaplasmid in two transcriptional units designated pcaDCHGB and pcaIJF. The pcaD promoter was mapped by primer extension, and expression from this promoter is demonstrated to be regulated by the LysR-type protein PcaQ. Beta-ketoadipate succinyl-coenzyme A (CoA) transferase activity in S. meliloti was shown to be encoded by SMb20587 and SMb20588, and these genes have been renamed pcaI and pcaJ, respectively. These genes are organized in an operon with a putative beta-ketoadipyl-CoA thiolase gene (pcaF), and expression of the pcaIJF operon is shown to be regulated by an IclR-type transcriptional regulator, SMb20586, which we have named pcaR. We show that pcaR transcription is negatively autoregulated and that PcaR is a positive regulator of pcaIJF expression and is required for growth of S. meliloti on protocatechuate as the carbon source. The characterization of the protocatechuate catabolic pathway in S. meliloti offers an opportunity for comparison with related species, including Agrobacterium tumefaciens. Differences observed between S. meliloti and A. tumefaciens pcaIJ offer the first evidence of pca genes that may have been acquired after speciation in these closely related species. (+info)