Mechanistic interpretation of the dilution effect for Azotobacter vinelandii and Clostridium pasteurianum nitrogenase catalysis.

Nitrogenase activity for Clostridium pasteurianum (Cp) at a Cp2:Cp1 ratio of 1.0 and Azotobacter vinelandii (Av) at Av2:Av1 protein ratios (R) of 1, 4 and 10 is determined as a function of increasing MoFe protein concentration from 0.01 to 5 microM.

Analysis of steady state Fe and MoFe protein interactions during nitrogenase catalysis.

Steady state kinetic measurements are reported for nitrogenase from Azotobacter vinelandii (Av) and Clostridium pasteurianum (Cp) under a variety of conditions, using dithionite as reductant. The specific activities of Av1 and Cp1 are determined as functions of Av2:Av1 and Cp2:Cp1, respectively, at component protein ratios from 0.4 to 50, and conform to a simple hyperbolic rate law for the interaction of Av2 with Av1 and Cp2 with Cp1.

Enhanced efficiency of ATP hydrolysis during nitrogenase catalysis utilizing reductants that form the all-ferrous redox state of the Fe protein.

The amount of MgATP hydrolyzed per pair of electrons transferred (ATP/2e) during nitrogenase catalysis (1.0 atm N(2), 30 degrees C) using titanium(III) citrate (Ti(III)) as reductant was measured and compared to the same reaction using dithionite (DT). ATP/2e values near 2.

A novel buffer system for separation of metal cations by capillary electrophoresis with indirect UV detection.

Generally, the buffers used for metal ion separations in capillary electrophoresis (CE) consist of a UV-active substance, pH-adjuster, and weak complexing reagent. This paper describes the successful separation of metal ions with a new buffer that contains no complexing reagent. Of several weakly basic compounds tested, 2-aminopyridine was selected as the most useful UV-active substance.

Comparison of serum total calcium, dialyzable calcium, and dialyzable magnesium in well and sick neonates.

We studied the relation of serum total calcium, dialyzable calcium, and dialyzable magnesium in 61 well and sick newborn infants aged 7-76 h. The infants' serum total calcium, dialyzable calcium and magnesium concentrations (ion chromatography method) were studied in comparison with the infant's history and sickness scale. We found that serum total calcium and dialyzable magnesium were lower in sick infants compared to well infants.