The interaction of two copper(II) complexes, namely [Cu(L 1 )Cl 2 ] 2 (1) and [Cu(L 2 )Cl 2 ] 2 (2), where L 1 = 1-amidino-O-methylurea and L 2 = N-(benzyl)-amidino-O-methylurea, with DNA has been thoroughly investigated using different characterization techniques, including electronic absorption spectroscopy, viscosity measurements, fluorescence spectroscopy, circular dichroism spectroscopy, thermal denaturation, stoichiometric determination, gel electrophoresis and atomic-force microscopy. The coordination compounds exhibit DNA binding potential by non-intercalation and DNA-cleaving ability through the oxidative pathway. Indeed, both complexes display antibacterial properties (against three bacteria involved in human-food poisoning, i.e.Salmonella, E. coli and Campylobacter). Furthermore, their cytotoxicity has been tested against three cancer cell lines, which are the small cell lung carcinoma (NCI-H187), the oral cavity carcinoma (KB) and the breast adenocarcinoma (MCF-7) and it was revealed that they are more cytotoxic than cisplatin against the NCI-H187 cancer cell line.
Microbacterium luteolum YK-1 has pyridoxine degradation pathway I. We have cloned the structural gene for the second step enzyme, pyridoxal 4-dehydrogenase. The gene consists of 1,026-bp nucleotides and encodes 342 amino acids. The enzyme was overexpressed under cold shock conditions with a coexpression system and chaperonin GroEL/ES. The recombinant enzyme showed the same properties as the M. luteolum enzyme. The primary sequence of the enzyme was 54% identical with that of D-threo-aldose 1-dehydrogenase from Agrobacterium tumefaciens, a probable aldo-keto reductase (AKR). Upon multiple alignment with enzymes belonging to the 14 AKR families so far reported, pyridoxal 4-dehydrogenase was found to form a new AKR superfamily (AKR15) together with A. tumefaciens D-threo-aldose 1-dehydrogenase and Pseudomonas sp. L-fucose dehydrogenase. These enzymes belong to a distinct branch from the two main ones found in the phylogenic tree of AKR proteins. The enzymes on the new branch are characterized by their inability to reduce the corresponding lactones, which are produced from pyridoxal or sugars. Furthermore, pyridoxal 4-dehydrogenase prefers NAD ؉ to NADP ؉ as a cofactor, although AKRs generally show higher affinities for the latter.
Four novel copper(ii) complexes based on guanidine derivatives have been synthesized by addition of N,N-heterocyclic ligands, and their interesting biological activities have been evaluated.
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