The kinetic behaviour of native bovine erythrocyte Cu,Zn superoxide dismutase (N-SOD) and of its derivatives by reaction with polyethylene glycol, acetic and succinic anhydrides has been investigated here in detail. Their responses to changes of pH and ionic strength (I) have been used as a probe for quantitatively displaying the relevance to kinetic rate constant of superficial positive charge...

The kinetic mechanism by which Escherichia coli RecBCD helicase unwinds duplex DNA was studied using a fluorescence stopped-flow method. Single turnover DNA unwinding experiments were performed using a series of fluorescently labeled DNA substrates containing duplex DNA regions ranging from 24 bp to 60 bp. All or no DNA unwinding time courses were obtained by monitoring the changes in fluoresce...

In this paper we demonstrate the utility of differential scanning calorimetry for investigating the thermodynamics and kinetics of a broad range of thin film reactions. We begin by describing differential scanning calorimeters and the preparation of thin film samples. We then cite a number of examples that illustrate how enthalpies of crystallization, heats of formation and enthalpies of interf...

The specific binding of [3H]phorbol 12,13-dibutyrate ([3H]PDBU) to participate preparations from mouse brain has been further characterized. Kinetic analysis, using a filtration assay to measure binding, yielded a second-order rate constant at 23°of 3.75 x 107 M~' min"1 and a first-order dissociation rate constant of 0.21 min~1. The Kd of 5.6 nw calculated from the kinetic data agreed well wit...

Human cytoplasmic antiproteinase (CAP) is an intracellular serpin that has been reported to utilize Arg341 as the reactive site P1 residue to neutralize a broad variety of extracellular serine proteases with trypsin-like specificity. Both native CAP and recombinant CAP purified from Escherichia coli were observed to form SDS-stable complexes not only with 125I-thrombin and 125I-urokinase, but a...

In order to solve nonlinear kinetic equations for recombination reactions when the production of participating species is driven externally at a time-dependent rate, we establish a framework based on the correspondence between these equations and a Schrodinger-type equation in which the product of the recombination constant with the production rate plays the role of the potential. The required ...

We describe a fluorescence assay that can be used to monitor helicase-catalyzed unwinding of duplex DNA continuously in real time. The assay is based on the observation that fluorescence resonance energy transfer (FRET) occurs between donor (fluorescein) and acceptor (hexachlorofluorescein) fluorophores that are in close proximity due to their covalent attachment to the 3' and 5' ends of the co...

The kinetics of electron attachment to CF(3) as a function of temperature (300-600 K) and pressure (0.75-2.5 Torr) were studied by variable electron and neutral density attachment mass spectrometry exploiting dissociative electron attachment to CF(3)Br as a radical source. Attachment occurs through competing dissociative (CF(3) + e(-) → CF(2) + F(-)) and non-dissociative channels (CF(3) + e(-) ...

Solvents can significantly alter the rates and selectivity of liquid-phase organic reactions, often hindering the development of new synthetic routes or, if chosen wisely, facilitating routes by improving rates and selectivities. To address this challenge, a systematic methodology is proposed that quickly identifies improved reaction solvents by combining quantum mechanical computations of the ...

The binding of inositol hexaphosphate (IHP) to oxyhemoglobin (oxy-Hb) was investigated by gel filtration and stopped flow kinetic methods. The stoichiometry of the complex is 1 IHP per hemoglobin tetramer in 0.05 M Z,Z-bis(hydroxymethyl)-2,2’,2”nitrilotriethanol (pH 7.0) containing 0.11 M NaCl and appears to approach 2 IHP per tetramer when the ionic strength is reduced to 0.01. The dissociatio...