title: Peroxidase activity-structure relationship of the intermolecular four-stranded G-quadruplex-hemin complexes and their application in Hg2+ ion detection.
abstract: The peroxidase activities of the complexes of hemin and intermolecular four-stranded G-quadruplexes formed by short-stranded X(n)G(m)X(p) sequences (X=A, T or C), especially T(n)G(m)T(p) sequences, were compared. The results, combining with those of circular dichroism (CD) spectra and acid-base transition study for DNA-hemin complexes, provide some important information about DNAzymes based on G-quadruplex-hemin complexes, such as the formation of a G-quadruplex structure is an important factor for determining whether a DNA sequence can enhance the catalytic activity of hemin; both intramolecular parallel G-quadruplexes and intermolecular four-stranded parallel G-quadruplexes can enhance the catalytic activity of hemin; the addition of T nucleotides to the 5'-end of a G-tract confers corresponding G-quadruplex greatly enhanced catalytic activity, whereas the addition of T nucleotides to the 3'-end of the G-tract has little effect; the high catalytic activity of hemin in the presence of some short-stranded G-rich sequences may be a result of the reduction of the acidity of the bound hemin cofactor. These studies provide more information for the DNA-hemin peroxidase model system, may help to elucidate the structure-function relationship of peroxidase enzymes and to develop novel, highly efficient peroxidase-liking DNAzymes. As a sequence of such an investigation, a new Hg(2+) detection method was developed.
authors.affiliation: Key Laboratory of Functional Polymer Materials, Ministry of Education, Nankai University, Tianjin, PR China. kongdem@nankai.edu.cn
authors.forename: De-Ming
authors.initials: DM
authors.lastname: Kong
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.forename: Na
authors.initials: N
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Han-Xi
authors.initials: HX
authors.lastname: Shen
mesh_terms: D002384:Catalysis; D002942:Circular Dichroism; D021881:DNA, Catalytic / Q000737:chemistry / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry* / Q000378:metabolism; D017669:Mercury Compounds / Q000032:analysis / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry* / Q000378:metabolism; D015203:Reproducibility of Results; D013329:Structure-Activity Relationship; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D021881:DNA, Catalytic; D017669:Mercury Compounds; D009841:Oligonucleotides; D014874:Water Pollutants, Chemical; D006427:Hemin; D009195:Peroxidase