A simple model is presented for analyzing a set of spectra obtained from spectrophotometric study of protein titration. With this model one can determine the states of (probable) intermediates in the course of protein unfolding. The model is developed based on abundance of native state, intermediate(s) and denatured state, and their contributions to differential absorbance at selected wavelengt...

In order to improve the activities of mycelium-bound ester hydrolases of Aspergillus oryzae Cs007, the main production conditions were investigated. The activities of the ester hydrolases were simultaneously determined by titration assay and spectrophotometric assay methods, using olive oil and p-nitrophenyl esters as substrates, respectively. The optimum carbon source and nitrogen source were ...

Extracts of frozen human pituitary glands contain, in addition to normal growth hormone (hGH (Mr = 22,005), a variant of lower molecular weight (approximately 20,000) (Singh, R. N. P., Seavey, B. K. and Lewis, U. J. (1974) Endocrinol. Res. Commun. 1, 449-464). This material, designated 20K hGH, occurs in various forms with the majority present as a heterologous dimer of Mr = 20,000 hGH and hGH....

4-(2-Methylbutyl)aminodipicolinic acid (H(2)MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pK(a)'s) and photophysical measurements. The pK(a)'s were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescenc...

Proteins can be bound to surfaces through chemical coupling reactions between the reactive groups of the protein and matrix. In this report, ribonuclease A immobilized on Silica beads, has been used as a model to study the modification of the properties of the enzyme after immobilization. The biological activity has been monitored by studying the binding of the inhibitor ~ytidine-3~-monophospha...

Spectrophotometric titration of pyridoxamine-pyruvate transaminase (EC 2.6.1.30) with pyridoxal at pH 7.15 gives four equivalent binding sites per tetramer. The pH dependence of the equilibrium constant for the association of 5'-deoxypyridoxal with the active site lysine residue was determined spectrophotometrically. These dissociation constants increase with increasing pH over the range pH 7.5...

We employed Circular Dichroism (CD) and UV/Vis-spectrophotometric methods to study the interaction of two Fe-containg cationic porphyrins: meso-tetra (4N-butylpyridyl) porphyrin [FeTButPyP4] and meso-tetra (4N-oxyethylpyridyl) porphyrin [FeTOEtPyP4] with DNA at various ionic strengths. The temperature-dependent absorption titration data were used to determine the binding constants and stoichiom...

Spectrophotometric titration in the ultraviolet has been employed to determine the pK values for dissociation of the sugar hydroxyls in pyrimidine arabinonucleosides and some of their O'-methyl and O'-ethyl derivatives. The order of dissociation of the sugar hydroxyls in the arabinofuranose ring was 2'-OH greater than 3'-OH greater than 5'-OH. The higher acidity (lower pK) of the 2'-OH was inte...

A bacterial strain, isolated from a cyanobacterial culture, was identified as Pseudomonas sp. strain X40. Under iron-limiting conditions, the Pseudomonas sp. produced aerobactin, a dihydroxamate siderophore previously found only in the family Enterobacteriaceae. Aerobactin was identified by electrophoretic mobility, spectrophotometric titration, proton nuclear magnetic resonance spectroscopy, m...

Nitrogen constitutes 78.09% by volume of dry unpolluted air, but it is a minor element with respect to its abundance in the earthj:"crust. Atmospheric nitrogen forms an important raw material for the economical synthesis of bulk chemicals of industrial importance, viz. ammonia, urea, nitrate, nitrite etc. Therefore, estimation of ammonia and its derivatives assumes a great importance for chemic...