Search results for "Biochemistry"
showing 10 items of 20172 documents
Structure, Biosynthesis, and Bioactivity of Photoditritide from Photorhabdus temperata Meg1
2019
A new cyclic peptide photoditritide (1), containing two rare amino acid d-homoarginine residues, was isolated from Photorhabdus temperata Meg1 after the nonribosomal peptide synthetase encoding gene pdtS was activated via promoter exchange. The structure of 1 was elucidated by HR-MS and NMR experiments. The absolute configurations of amino acids were determined according to the advanced Marfey's method after hydrolysis of 1. Bioactivity testing of 1 revealed potent antimicrobial activity against Micrococcus luteus with an MIC value of 3.0 μM and weak antiprotozoal activity against Trypanosoma brucei rhodesiense with an IC50 value of 13 μM. Additionally, the biosynthetic pathway of 1 was als…
In Vivo Studies on the Anti-Inflammatory Activity of Pachymic and Dehydrotumulosic Acids
2000
Pachymic and dehydrotumulosic acids were studied in different models of acute and chronic inflammation. They proved to be active in most of the methods applied. None of them were active against arachidonic acid-induced ear edema. Dehydrotumulosic acid significantly diminished the mouse ear edema induced by ethyl phenylpropiolate, while pachymic acid was ineffective. When the putative corticoid-like mechanism of both compounds was explored, pachymic acid activity was partially abolished by the glucocorticoid receptor antagonist progesterone, but dehydrotumulosic acid activity was not affected. In vivo experiments demonstrated the inhibition by both principles of the phospholipase A2 (PLA2)-i…
Targeting a Targeted Drug: An Approach Toward Hypoxia-Activatable Tyrosine Kinase Inhibitor Prodrugs
2016
Tyrosine kinase inhibitors (TKIs), which have revolutionized cancer therapy over the past 15 years, are limited in their clinical application due to serious side effects. Therefore, we converted two approved TKIs (sunitinib and erlotinib) into 2-nitroimidazole-based hypoxia-activatable prodrugs. Kinetics studies showed very different stabilities over 24 h; however, fast reductive activation via E. coli nitroreductase could be confirmed for both panels. The anticancer activity and signaling inhibition of the compounds against various human cancer cell lines were evaluated in cell culture. These data, together with molecular docking simulations, revealed distinct differences in the impact of …
Immunonegative Staining: Epitope Localization on Macromolecules
1996
Relevant literature relating to immunonegative staining is reviewed and integrated with current research of the author and others. The immunonegative staining procedure has been utilized for the study of epitope localization on immune complexes formed from keyhole limpet hemocyanin type 2 (KLH2) di- and multidecamers, and the 20S and 26S proteasome from Xenopus laevis. The IgG linkage pattern of molecules in small immune complexes is considered to provide the most reliable indication of epitope location. For both KLH2 and the 20S proteasome, using domain-specific monoclonal antibodies and a 32-kDa (p32) subunit-specific polyclonal antibody, respectively, it is shown that epitopes (KLH2, sub…
Gut Microbiota Cannot Compensate the Impact of (quasi) Aposymbiosis in Blattella germanica
2021
Simple Summary The German cockroach Blattella germanica is a good model to study complex symbiotic relationships because the following two symbiotic systems coexist in a single individual: the endosymbiont Blattabacterium (living inside specialized cells called bacteriocytes) and the gut microbiota. Although the role of the endosymbiont has been fully elucidated, the function of the gut microbiota remains unclear. The study of the gut microbiota will benefit from the availability of insects deprived of Blattabacterium. Our goal is to determine the effect of the removal (or, at least, the reduction) of the endosymbiont population on the cockroach’s fitness, in a normal gut microbiota communi…
Benzodiazepines: specific competitors for the binding of L-tryptophan to human serum albumin.
1975
By means of the gel filtration technique, the effect of nine benzo-diazepine derivates on the binding of l-tryptophan to human serum albumin was investigated. Using equimolar tryptophan and benzodiazepine concentrations, all benzodiazepines with binding constants higher than 104 (M−1), displace l-tryptophan from its binding site to a high degree. The mechanism of the displacement was characterized as a competition for a common binding site. Some of the benzodiazepines displace l-tryptophan to a greater extent than salicylic acid. The benzodiazepines and tryptophan are the only substances known with a high degree of stereospecific binding to human serum albumin. This study shows that there i…
Monoclonal antibodies and antibody fragments: state of the art and future perspectives in the treatment of non-haematological tumors
2011
Introduction: The use of monoclonal antibodies is one of the strategies for targeting the specific key points of the main pathways of cancer growth and survival, but only a few antibodies have offered a clear clinical benefit in the treatment of non-haematological malignancies. Areas covered: This review summarizes the general properties of monoclonal antibodies, including structure, nomenclature and production techniques. The antibodies approved for use in clinical practice for the treatment of non-haematological tumors and those antibodies still being developed in this setting are briefly described. The types of antibody fragments are also reported. Expert opinion: Monoclonal antibodies w…
Stimuli-responsive bile acid-based metallogels forming in aqueous media
2015
Abstract The synthesis and gelation properties of a picolinic acid conjugated bile acid derivative in the presence of metal salts along with the stimuli-responsiveness of the systems are reported. The gels are formed in the presence of Cu 2+ ions in the solvent systems composed of 30–50% of organic solvent (MeOH, acetonitrile, or acetone) in water. The gels respond to various stimuli: they can be formed upon sonication or shaking, and their gel–sol transformation can be triggered by a variety of chemical species. NMR, MS, and SEM techniques are exploited in order to gain a deeper insight on the self-assembled systems.
Design, synthesis, DNA-binding and cytotoxicity evaluation of new potential combilexines
2002
Combilexines, compounds in which a DNA intercalator is linked to a minor groove binding component, interact with the DNA in a sequence specific manner to yield in most cases compounds with anticancer activity. A series of new compounds closely related to netropsin in which the two components were linked by an amide group was synthesised as potential combilexines. As some of these compounds showed cytotoxic activity in vitro, an attempt was made to rationalise their mechanism of action. The DNA binding characteristics of the carboxamides were evaluated by thermal denaturation experiments and by ethidium bromide displacement assay. Their ability to inhibit the topoisomerase I was also determi…
Correction: Total synthesis of two potent anti-inflammatory macrolactones of the oxacyclododecindione type
2015
Correction for ‘Total synthesis of two potent anti-inflammatory macrolactones of the oxacyclododecindione type’ by Johannes Tauber et al., Org. Biomol. Chem., 2015, 13, 7813–7821.