Kinetics of interaction of Cotton Leaf Curl Kokhran Virus-Dabawali (CLCuKV-Dab) coat protein and its mutants with ssDNA

Gemini viral assembly and transport of viral DNA into nucleus for replication, ssentially involve DNA-coat protein interactions. The kinetics of interaction of Cotton LeafCtirl Kokhran Virus-Dabawali recombinant coat protein (rCP) with DNA was studied by electrophoretic mobility shift assay (EMSA) and Surface plasmon resonance (SPR). The rCP interacted with ssDNA with a K-A, of 2.6 +/- 0.29 x 10(8) M-1 in a sequence non-specific manner. The CP has a conserved C2H2 type zinc finger motif composed of residues C68, C72, H81 and H85. Mutation of these residues to alanine resulted in reduced binding to DNA probes. The H85A mutant rCP showed the least binding with approximately 756 fold loss in the association rate and a three order magnitude decrease in the binding affinity as compared to rCP. The CP-DNA interactions via the zinc finger motif could play a Crucial role ill Virus assembly and in nuclear transport. (C) 2009 Elsevier Inc.

Interaction of manganese(II) with valinomycin: Observation of mixed complexes

The interaction of antibiotic valinomycin with manganese (II) has been studied using circular dichroism, electron spin resonance and infrared techniques. Results show that Mn(II) forms complexes with valinomycin in both 2:1 (valinomycin-ion-valinomycin sandwich) and 1:1 (equimolar) stoichiometries. The 1:1 type observed here is very different from the well known K+-valinomycin bracelet conformation.

Coordinative interaction of morpholine with divalent metallo tetraphenyl porphyrins

The formation of axially coordinated morpholine (morph) complexes of MTPP, (M = Co, Ni, Cu and Zn) has been studied. Morpholine coordinates through imino nitrogen to the metal ions with the retainment of equatorial conformation. The presence of spin-free, NiTPP (morph), (S = 1) and an equilibrium mixture of CoTPP and an oxygen adduct of CoTPP (morph) in solution have been observed.

Resolution of racemic gossypol and interaction of individual enantiomers with serum albumins and model peptides

Racemic gossypol has been resolved by HPLC separation of diastereomeric (−) norepinephrine adducts on a reverse-phase column. The binding constants for the interaction of the three gossypol forms (+, − and −) with human and bovine serum albumins have been determined by fluoresence quenching studies. The KD values demonstrate that all three forms bind equally effectively to the two proteins, suggesting an absence of chiral discrimination in albumin-gossypol interactions. Circular dichroism studies of (+)-gossypol binding to the model dibasic peptides, Boc-Lys-Pro-Aib-Lys-NHMe and gramicidin S, suggesting that distortions of binaphthyl geometry may occur only for specific orientations of interacting residues at the receptor site.

Interaction of rat testis protein, TP, with nucleic acids in vitro. Fluorescence quenching, UV absorption, and thermal denaturation studies

The nucleic acid binding properties of the testis protein, TP, were studied with the help of physical techniques, namely, fluorescence quenching, UV difference absorption spectroscopy, and thermal melting. Results of quenching of tyrosine fluorescence of TP upon its binding to double-stranded and denatured rat liver nucleosome core DNA and poly(rA) suggest that the tyrosine residues of TP interact/intercalate with the bases of these nucleic acids. From the fluorescence quenching data, obtained at 50 mM NaCl concentration, the apparent association constants for binding of TP to native and denatured DNA and poly(rA) were calculated to be 4.4 X 10(3) M-1, 2.86 X 10(4) M-1, and 8.5 X 10(4) M-1, respectively. UV difference absorption spectra upon TP binding to poly(rA) and rat liver core DNA showed a TP-induced hyperchromicity at 260 nm which is suggestive of local melting of poly(rA) and DNA. The results from thermal melting studies of binding of TP to calf thymus DNA at 1 mM NaCl as well as 50 mM NaCl showed that although at 1 mM NaCl TP brings about a slight stabilization of the DNA against thermal melting, a destabilization of the DNA was observed at 50 mM NaCl. From these results it is concluded that TP, having a higher affinity for single-stranded nucleic acids, destabilizes double- stranded DNA, thus behaving like a DNA-melting protein.

Interaction Of Oxygen With Zn(0001) Surface

EELS and XPS studies show the presence of both adsorbed atomic and molecular oxygen at low temperatures. The nature of the oxide layer formed on the surface has been characterized by angular dependent and variable temperature EELS. A loss peak around 550 cm−1 is assigned to an electronic transition.

Hydroxylation of oxygen-covered Cu(110) and Zn(0001) surfaces by interaction with CH3OH, (CH3)2NH, H2S, HCl and other proton donor molecules

EELS studies provide definitive evidence for the hydroxylation of oxygen-covered Cu(110) and Zn(0001) surfaces on interaction with proton donor molecules such as H2O, CH3OH, HCOOH, NH3 and (CH3)2NH. The occurrence of surface hydroxylation is unambigouusly shown by a study of the interaction of H2S and HCl with an oxygen covered Cu(110) surface.

A novel investigation of vapor-phase charge-transfer complexes of halogens with n-donors by electron energy loss spectroscopy

Complexes of I2 with diethyl ether and triethylamine and of Br, with diethyl ether have been investigated in the vapor phase for the first time by employing electron energy loss spectroscopy. Besides the CT bands, blue-shifted vacuum-UV bands of the halogens have been assigned; the amine-I, system appears to exhibit two CT bands,associated with two different excited states of the complex.

Area Efficient Loop Filter Design for Charge Pump Phase Locked Loop

In this paper, two new dual-path based area efficient loop filtercircuits are proposed for Charge Pump Phase Locked Loop (CPPLL). The proposed circuits were designed in 0.25 CSM analog process with 1.8V supply. The proposed circuits achievedup to 85% savings in capacitor area. Simulations showed goodmatch of the new circuits with the conventional circuit. Theproposed circuits are particularly useful in applications thatdemand low die area.

An NMR study of the interaction of cytosine arabinoside and lysozyme

Abstract is not available.

Singlet and triplet molecular interaction in excimers

A perturbative approach is developed to determine, term by term, the contributions of the various forces to the excimer potentials of the singlet and triplet excimers. The results show that the singlet excimer of naphthalene is more stable than the corresponding triplet excimer primarily due to large contributions of the exciton-resonance and the dispersion energy terms. The variation of the various terms with the conformations of the excimers suggests that the singlet and triplet excimers of naphthalene cannot have identical structure.

Interaction of Alpha-tocopherol with diphenylpicryl hydrazyl a means to determine the polarity of the environment around Alpha-tocopherol and its binding with lipids

Alpha-Tocopherol is found to interact with the stable free radical DPPH orders of magnitude faster than ordinary phenols. It is suggested that the high reactivity arises from the coplanarity of the C-O-C framework with the aromatic ring. The rate constant of the reaction of Alpha-tocopherol with DPPH increases progressively with solvent polarity and can be quantitatively related to Kosower's Z parameter. Fatty acid derivatives slow down the reaction with DPPH due to binding with Alpha-tocopherol.

Kinetic mechanism of the interaction of D-cycloserine with serine hydroxymethyltransferase

The kinetic mechanism for the interaction of D-cycloserine with serine hydroxymethyltransferase (EC2.1.2.1) from sheep liver was established by measuring changes in the activity, absorbance, and circular dichoism (CD) of the enzyme. The irreversible inhibition of the enzyme was characterized by three detectable steps: an initial rapid step followed by two successive steps with rate constants of 5.4 X s-l and 1.4 X lo4 s-l. The first step was distinguished by a rapid disappearance of the enzyme absorbance peak at 425 nm, a decrease in the enzyme activity to 25% of the uninhibited velocity, and a lowering of the CD intensity at 432 nm to about 65% of the original value. The second step of the interaction was accompanied by a complete loss of enzyme.

On solitons with half integral charge

Can certain soliton states, with half integral expectation value of charge, be also eigenstates of charge X with half integral eigenvalue? It can be so only with a somewhat sophisticated definition of charge.