The steady-state kinetics of chicken liver fatty acid synthase has been studied over the pH range 5.9-8.6 in 0.1 M potassium phosphate/1 mM EDTA at 25.0 degrees C. The steady-state initial velocity, v, which was determined by measuring the rate of consumption of NADPH spectrophotometrically over a wide range of substrate concentrations, followed the rate law v = (formula; see text), in which Ac...

An auxin-binding protein can be solubilized from microsomal membranes of Zea mays using either Triton X-100 extraction of the membranes or buffer extraction of the acetone-precipitated membranes. This paper describes the properties of the binding protein solubilized by these two methods. The binding is assayed by gel filtration chromatography in the presence of naphthalene [2-(14)C]acetic acid....

surfactant molecules are used as interesting tools to study the structure, function and stability of proteins. protonation states of amino acids may be changed in the presence of surfactants. in this work, using experimental observations and molecular dynamic simulation, the effects of sodium dodecyl sulfate on the acid dissociation constants of tryptophan was examined. the acid–base equilibriu...

The rate and equilibrium constants for the formation and dissociation of the bovine ventricular (BV) actomyosin-S1-ADP have been measured by stopped flow light scattering. A comparison of the rate constants obtained here with those for rabbit skeletal (RS) actomyosin-S1 indicates that there are large differences in several of the rate and equilibrium constants. 1) The rate constant of ADP disso...

This paper describes convenient preparations of heterogeneous multisectional polyacrylamide slab gels and the protocols that use these gels to measure protein-ligand binding constants [using bovine carbonic anhydrase B (CAB) as a model system]. Unlike procedures for affinity electrophoresis using tube gels, all binding information concerning protein-ligand interactions was encoded in a single m...

The dissociation kinetics of cooperatively bound bacteriophage T4 gene 32 protein from a variety of single-stranded homopolynucleotides has been investigated by stopped-flow techniques. Irreversible dissociation of the complexes was induced by rapidly increasing the salt concentration and monitoring the increase in tryptophan fluorescence upon dissociation of the gene 32 protein. The dependence...

According to the classical theory of the dissociation of weak electrolytes, the amino acids show much lower basic and acidic dissociation constants than would be expected from a comparison with other weak acids and bases. In order to explain this anomaly, Adams (1) originally suggested that an ampholyte must necessarily exist almost entirely as an “inner salt.” Bjerrum (2) extended this idea wi...

The reaction between carboxyhemoglobin and reduced microperoxidase (MP): Hb4(CO)4 + 4MP=Hb4 + 4MPCO, recently reported by us, has been further studied. By generating species Hb4(CO), Hb4(CO)2, and Hb(CO)3 in the stopped flow cuvette by the reaction of dithionite with the species of the general formula Hb4(O2)x(CO)y(x + y=4) in the presence of microperoxidase it has been possible to determine th...

Myoglobin (Mb) buffers intracellular O2 and facilitates diffusion of O2 through the cell. These functions of Mb will be most effective when intracellular PO2 is near the partial pressure of oxygen at which Mb is half saturated (P50) of the molecule. We test the hypothesis that Mb oxygen affinity has evolved such that it is conserved when adjusted for body temperature among closely related anima...