We have studied the kinetics of the gelation process that occurs upon warming cold extracts of Acanthamoeba using a low-shear falling ball assay. We find that the reaction has at least two steps, requires 0.5 mM ATP and 1.5 mM MgCl2, and is inhibited by micromolar Ca++. The optimum pH is 7.0 and temperature, 25 degrees-30 degrees C. The rate of the reaction is increased by cold preincubation wi...

The chemical reactivity of fully maleylated horse heart cytochrome c with oxidants, reductants, and iron ligands was studied in the presence and absence of MgCl2. In the absence of salt, the partly unfolded protein reacts rapidly with cyanide in the ferric state (k = 235 M-1s-1); the reaction is exothermic (delta H = -9.4 kcal/mol) and entropically unfavored (delta S = -7.0 e.u.). In 0.01 M MgC...

In support of the RNA world hypothesis, previous studies identified trimetaphosphate (Tmp) as a plausible energy source for RNA world organisms. In one of these studies, catalytic RNAs (ribozymes) that catalyze the triphosphorylation of RNA 5'-hydroxyl groups using Tmp were obtained by in vitro selection. One ribozyme (TPR1) was analyzed in more detail. TPR1 catalyzes the triphosphorylation rea...

Properties of calf thymus chromatin, prepared by mild procedures, have been studied in various solvents. In 0.2 mM EDTA s-values ranged from 20 to 30 S and intrinsic viscosities from 5 to 24 dl/g. Dialysis against 0.15 M NaCl or 0.2 mM MgCl2 changed these values to 80 to 100 S and 0.2 to 5 dl/g, respectively, indicating an essentially more compact structure. In 0.2 mM EDTA X-ray scattering yiel...

1. A simple method is described for calculating the free concentrations of all species in a mixture of several ionic components that associate at equilibrium to any extent and with any stoicheiometry. 2. It can readily be adapted to take account of species such as protons for which the free rather than the total concentrations are controlled. 3. It was applied to mixtures of adenine nucleotides...

Transport properties of concentrated electrolytes have been analyzed using classical molecular dynamics simulations with the algorithms and parameters typical of simulations describing complex electrokinetic phenomena. The electrical conductivity and transport numbers of electrolytes containing monovalent (KCl), divalent (MgCl2), a mixture of both (KCl + MgCl2), and trivalent (LaCl3) cations ha...

Recently, we reported on main group metal complexes of tridentate polyimido sulfur ligands with a phosphorus [1] or a nitrogen [2, 3] side-arm. These monoanionic ligands have the general formulae {R2PCH2S(NR)2} (R1 = Me, Ph; R2 = tBu, SiMe3) and {R2N(spacer)S(NR)2} (R1 = Me; R2 = tBu, SiMe3, spacer = 0, (CH2)n, C6H4). Metal complexes are accessible via salt elimination from the dimer [Li{Me2PCH...

We demonstrate that despite lacking a 3'----5' proofreading exonuclease, the Thermus aquaticus (Taq) DNA polymerase can catalyze highly accurate DNA synthesis in vitro. Under defined reaction conditions, the error rate per nucleotide polymerized at 70 degrees C can be as low as 10(-5) for base substitution errors and 10(-6) for frameshift errors. The frequency of mutations produced during a sin...

Effect of salts (Na2SO4, Na2CO3, MgSO4, NaCl, MgCl2), soil extract and polyethylene glycol (PEG-6000) on the germination of Chenopodium glaucum L., seed was studied. Maximum germination was obtained in distilled water. Germination decreased with increase in salinity. The inhibition of germination by salt solutions was in the order of MgCl2 > Na2SO4 > Na2CO3 > NaCl > Soil extract > MgSO4. Germin...