Hypercholesterolemia has been reported to be the main cause of cardiovascular diseases and the leading cause of death. Therefore, decreasing serum cholesterol level is very important for preventing the cardiovascular diseases. It has been supposed that probiotics in human gastrointestinal tract have the ability to decrease serum cholesterol level by reducing the absorption of cholesterol from the intestinal tract and the bile salt deconjugation. In this study, 28 strains of Lactobacillus spp., isolated from breast-fed infant's feces, were identified and investigated for their bile salt deconjugation ability. The deconjugation ability of the strains was determined by the release of cholic acid resulting from the deconjugation of conjugated bile salts. Research results showed that four of the strains had bile salt deconjugation ability. The strains with deconjugation ability have been identified in species level by using biochemical test, and molecular techniques, API 50CHL test and 16S rRNA gene sequence analysis respectively. LP1, E3, and E9 strains with deconjugation activity were identified as Lactobacillus rhamnosus and GD2 strain as Lactobacillus plantarum. Even if oxgall decreases the viability of bacteria, the highest amount of cholesterol precipitation (42%) was performed by GD2 strain in the presence of 0.3% (w/v) bile. This study demonstrated that the identified Lactobacillus strains had an excellent ability to survive at low pH, a high bile deconjugation ability, and hypocholesterolemic effect in in vitro conditions.
The heme-copper superfamily of proton-pumping respiratory oxygen reductases are classified into three families (A, B, and C families) based on structural and phylogenetic analyses. Most studies have focused on the A family, which includes the eukaryotic mitochondrial cytochrome c oxidase as well as many bacterial homologues. Members of the C family, also called the cbb 3 -type oxygen reductases, are found only in prokaryotes and are of particular interest because of their presence in a number of human pathogens. All of the heme-copper oxygen reductases require proton-conducting channels to convey chemical protons to the active site for water formation and to convey pumped protons across the membrane. Previous work indicated that there is only one proton-conducting input channel (the K C channel) present in the cbb 3 -type oxygen reductases, which, if correct, must be utilized by both chemical protons and pumped protons. In this work, the effects of mutations in the K C channel of the cbb 3 -type oxygen reductase from Rhodobacter capsulatus were investigated by expressing the mutants in a strain lacking other respiratory oxygen reductases. Proton pumping was evaluated by using intact cells, and catalytic oxygen reductase activity was measured in isolated membranes. Two mutations, N346M and Y374F, severely reduced catalytic activity, presumably by blocking the chemical protons required at the active site. One mutation, T272A, resulted in a substantially lower proton-pumping stoichiometry but did not inhibit oxygen reductase activity. These are the first experimental data in support of the postulate that pumped protons are taken up from the bacterial cytoplasm through the K C channel.
Water lilies are aquatic, ornamental and economically valuable plants classified under Nymphaea genus. Nymphaea alba L., white water lily, has a special focus since it is a member of basal angiosperms. Alternative oxidase (AOX) proteins are the terminal oxidases in the electron transport chain of plants. Identification of alternative oxidase encoding genes for basal angiosperms is important to increase the quality of phylogenetic studies. However, AOX encoding genes were yet to be discovered for N. alba. In this study, we aimed to identify alternative oxidase encoding genes in N. alba by performing transcriptome analysis. Annotation of 272,934 unigenes with Trinotate tool revealed 77 transcripts with AOX domains characterized in known alternative oxidases. Blast analysis of these 77 sequences with known AOX proteins revealed three distinct AOX genes (AOX1, AOX2 and AOX4) in N. alba. After in silico subcellular localization analysis of three identified AOX proteins, AOX1, AOX2 are predicted as mitochondrial while AOX4 is a plastidic alternative oxidase protein. Template-based structural modeling results showed that all identified proteins are statistically similar to known structure models of corresponding AOXs.
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