Complex Binds (complex + bind)

Distribution by Scientific Domains


Selected Abstracts


Human rhinovirus 3C protease: a cysteine protease showing the trypsin(ogen)-like fold

BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 4 2001
Martino Bolognesi
Abstract Viral-encoded proteases cleave precursor polyprotein(s) leading to maturation of infectious virions. Strikingly, human rhinovirus 3C protease shows the trypsin(ogen)-like serine protease fold based on two topologically equivalent six-stranded ,-barrels, but displays residue Cys147 as the active site nucleophile. By contrast, papain, which is representative of most cysteine proteases, does not display the trypsin(ogen)-like fold. Remarkably, in human rhinovirus 3C cysteine protease, the catalytic residues Cys147, His40 and Glu71 are positioned as Ser195, His57 and Asp102, respectively, building up the catalytic triad of serine proteases in the chymotrypsin-trypsin-elastase family. However, as compared to trypsin-like serine proteases and their zymogens, residue His40 and the oxyanion hole of human rhinovirus 3C cysteine protease, both key structural components of the active site, are located closer to the protein core. Human rhinovirus 3C cysteine protease cleaves preferentially Gin , Gly peptide bonds or, less commonly, the Gin , Ser, Gin ,Ala, Glu , Ser or Glu ,Gly pairs. Finally, human rhinovirus 3C cysteine protease and the 3CD cysteine protease-polymerase covalent complex bind the 5° non-coding region of rhinovirus genomic RNA, an essential function for replication of the viral genome. © 2001 IUBMB. Published by Elsevier Science Ltd. All rights reserved. [source]


Metal-complex formation and DNA interaction of 5, 10,15,20-tetrakis(1-methyl-4-pyridiyl)-porphine: Study of the mechanistic aspects

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2010
Sabriye Aydinoglu
The macrocyclic porphyrin 5,10,15,20-tetrakis(1-methyl-4-pyridiyl)-porphine is studied in its ability to coordinate Cu(II) even at very low pH values and to interact, as a copper complex, with calf-thymus (CT-DNA). The kinetics and equilibria for metal-ligand complexes formation are spectrophotometrically studied, particularly focussing on the mechanistic information provided by the kinetic approach. The rate constants of complex formation is much lower than that of water exchange at Cu(II); this behavior is ascribed to an equilibrium between two porphyrin populations, only one of them being reactive. Concerning the interaction of the copper,porphyrin complex (D) with CT-DNA, it has been found that the complex binds to G,C base pairs by intercalation while forms external complex with the A,T base pairs. The kinetic results agree with a reaction mechanism that takes into account the slow shuffling from an AT-bound form (DAT) to a GC-bound form (DGC) of the copper complex (D), finally leading to a more stable DGC* intercalated form. Kinetic and equilibrium parameters for the copper complex binding to the nucleic acid are obtained, and the binding mechanism is discussed. A mechanism is proposed where D reacts simultaneously with (G,C) and (A,T) base pairs. The resulting bound forms interconvert according to a "shuffling" process, which involves formation of an intermediate (DGC) form. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 79,89, 2010 [source]


Multiple promoter elements required for leukemia inhibitory factor-stimulated M2 muscarinic acetylcholine receptor promoter activity

JOURNAL OF NEUROCHEMISTRY, Issue 4 2006
George S. Laszlo
Abstract Treatment of neuronal cells with leukemia inhibitory factor (LIF) results in increased M2 muscarinic acetylcholine receptor promoter activity. We demonstrate here that multiple promoter elements mediate LIF stimulation of M2 gene transcription. We identify a LIF inducible element (LIE) in the M2 promoter with high homology to a cytokine-inducible ACTG-containing sequence in the vasoactive intestinal peptide promoter. Mutagenesis of both a STAT (signal transducers and activators of transcription) element and the LIE in the M2 promoter is required to attenuate stimulation of M2 promoter activity by LIF completely. Mobility shift assays indicate that a LIF-stimulated complex binds to a 70 base pair M2 promoter fragment. Furthermore, a STAT element within this fragment can bind to LIF-stimulated nuclear STAT1 homodimers in vitro. Mutagenesis experiments show that cytokine-stimulated activation of M2 promoter activity requires tyrosine residues on glycoprotein 130 (gp130) that are also required for both STAT1 and STAT3 activation. Dominant negative STAT1 or STAT3 can block LIF-stimulated M2 promoter activity. Real-time RT-PCR analysis indicates that LIF-stimulated induction of M2 mRNA is partially dependent on protein synthesis. These results show that regulation of M2 gene transcription in neuronal cells by LIF occurs through a complex novel mechanism that is dependent on LIE, STAT and de novo protein synthesis. [source]


Resonance Raman spectroscopic studies of [Ru(phen)2qdppz]2+ and its interactions with calf thymus DNA

JOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2004
B. Abraham
Abstract Resonance Raman (RR) spectroscopy was employed to study the metal to ligand charge transfer (MLCT) and intraligand transition (IL) state of the [Ru(phen)2qdppz]2+ complex, where phen = 1, 10-phenanthroline and qdppz = naphtho[2,3- a]dipyrido[3,2- h:2,,3, - f]phenazine-5,18-dione. The vibrational bands were assigned based on the data available for [Ru(phen)2dppz]2+ (dppz = dipyrido[3,2- a:2,,3, - c]phenazine), [Ru(dppz)3]2+ and [Ru(phen)3]2+. The tail end of the MLCT band is inferred to be the Ru , qdppz localized transition based on vibrational intensity analysis. On intercalation with DNA, the modes assigned to qdppz decrease in intensity owing to ,, stacking interactions with the DNA bases. RR data show that the above complex binds to DNA through intercalation via the qdppz moiety. Copyright © 2003 John Wiley & Sons, Ltd. [source]