Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To define the mechanism of the protection by ecabet sodium of the gastric mucosa, the characteristics of protein binding of this drug were investigated using a quartz-crystal microbalance (QCM) method. The binding rate constants (kb) and the binding amounts (delta m) were obtained from time courses of the frequency decrease (mass increase) of the QCM. The binding constants to proteins of two ecabet analogues (G1, ecabet type and G2, non-ionic ecabet type) were dependent on the pH, leading to large kb values at the acidic region. Furthermore, the kb values of G1 with the addition of bovine serum albumin (BSA) and bovine serum fibrinogen (BSF) at the acid region were larger than those of G2. The difference in kb values between G1 and G2 for porcine gastric mucin (PGM) is hardly discernible. Ecabet seems to be more heavily distributed in the ulcerous areas than in the intact mucosa, judging from the large binding constants of this drug to BSA and BSF compared with those to PGM. It is suggested that ecabet is bound to proteins by hydrophobic interaction, moreover, the electrostatic interaction between this drug and proteins (BSA and BSF) occurs at acidic pH region. On account of these interactions, ecabet sodium seems to have a more protective effect on an ulcer at intraluminal acidity than sucralfate. Finally, QCM was found to be a useful technique for detecting quantitatively the time course of binding proteins with drug.
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PMID:A kinetic study of protein binding to ecabet sodium using quartz-crystal microbalance. 1043 94

Using UV-vis spectrometrical measurements, equilibrium constants for NO transfer between S-nitroso-N-acetyl-penicillamine (SNAP) and different thiols as well as kinetic data for NO transfer from S-nitroso bovine serum albumin (BSANO) to thiols have been obtained. NO transfer from SNAP to other primary/secondary thiols are thermodynamically favorable, whereas other S-nitrosothiols exhibit similar NO transfer potential. The obtained Gibbs free energy, enthalpy and entropy data indicated that NO transfer reactions from SNAP to four thiols are exothermic with entropy loss. The kinetic behavior of BSANO/RSH transfer can be related to both the acidity of sulfhydryl group and the electronic structure in thiol.
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PMID:Equilibrium and kinetics studies of transnitrosation between S-nitrosothiols and thiols. 1121 29

This paper investigated the interaction of acidic chrome blue K with bovine serum albumin (BSA). When BSA was added into acidic chrome blue K solution at pH 2.87 HCl-NaAc buffter, bathochromic effect and hypochromicity were observed. With the increase in BSA concentration, the absorption peak at 523 nm decreased. It was considered that the combination of BSA with acidic chrome blue K is due to static electricity forces. The interaction is in accord with model of phase distribution. It was discussed the effect of acidity, concentration of acidic chrome blue K, ion strength to apparent binding constant Kc, binding number n, Sandell constant. The reaction time, surfactant, work curve were studied.
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PMID:[Spectra studies on interaction of bovine serum albumin with acidic chrome blue K in acidic solution]. 1291 2

In this study, we show that the difference in acidity of functional groups in porphyrin photosensitizers provides a meaningful avenue to achieve differential localization and retention of porphyrins in tissues and cells, and in the end could be a positive factor in the photodynamic treatment of cancer (PDT). We have demonstrated that meso-tetraphenylporphyrin derivative with four phosphonate (bond P(double bond O)(bond OH)(2)) moieties exists in aqueous solutions mainly in four forms that differ by a degree of protonation of the porphyrin ring and ionization of the phosphonate group. It is shown that each porphyrin form has different affinities toward the model protein (bovine serum albumin, BSA). Thus pH of the medium significantly modulates the affinity of the phosphonate porphyrin toward BSA. At lower pH (pH 6.0), the phosphonate porphyrin and BSA form a complex with affinity constant of K(b)=6.9 x 10(5) M(-1), while at pH 7.0 the K(b)=6.1 x 10(5) M(-1). At pH 8.0 the association is significantly lower. Because cancerous cells have generally lower pH (pH approximately 6.9) compared to healthy cells (pH approximately 7.4), the pH of such cells could be a decisive factor for cellular retention of the porphyrin in the form of an associate with intracellular proteins. Moreover, we have also demonstrated that the protonation/deprotonation equilibria do not negatively affect the photophysical properties or ability of phosphonate porphyrin to generate singlet oxygen.
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PMID:Modulation of porphyrin binding to serum albumin by pH. 1472 40

The aim of this study was to examine the stability of bovine serum albumin (BSA) in poly(DL-lactic acid-co-glycolic acid) (PLGA) microspheres upon addition of a new excipient, poly(ethylene glycol)-poly(L-histidine) diblock copolymer (PEG-PH). Poly(L-histidine) component can form an ionic complex with BSA under acidic conditions within a narrow pH range. To optimize the ionic complexation conditions for BSA with PEG-PH, the resulting complex sizes were monitored using the Zetasizer. PLGA microspheres containing BSA as a model protein were prepared by w/o/w double emulsion method. BSA stability in aqueous solutions and after release from PLGA microspheres was determined using circular dichroism (CD) spectroscopy for secondary structure analyses and fluorescence measurements for tertiary structure analyses. The release profile of BSA from the microspheres was monitored using UV spectrophotometry. The rate of PLGA degradation was monitored by gel permeation chromatography. The pH profile within microspheres was further evaluated by confocal microscopy using a pH-sensitive dye. Approximately 19 PEG-PH molecules and one BSA molecule coalesced to form an ionic complex around a pH range of 5.0-6.0. Plain BSA/PLGA and BSA/PEG-PH/PLGA microspheres had a mean size of 27-35 microm. PLGA microspheres with a BSA loading efficiency >80% were prepared using the double emulsion method. PEG-PH significantly improved the stability of BSA both in aqueous solutions and in PLGA microspheres. The release profiles of BSA from different formulations of PLGA microspheres were significantly different. PEG-PH effectively buffered the local acidity inside the microspheres and improved BSA release kinetics by reducing initial burst release and extending continuous release over a period of time, when encapsulated as an ionic complex. PLGA degradation rate was found to be delayed by PEG-PH. There was clear evidence that PEG-PH played multiple roles when complexed with BSA and incorporated into PLGA microspheres. PEG-PH is an effective excipient for preserving the structural stability of BSA in aqueous solution and BSA/PLGA microspheres formulation.
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PMID:Stability of bovine serum albumin complexed with PEG-poly(L-histidine) diblock copolymer in PLGA microspheres. 1626 69

The effect of high-intensity pulsed electric fields (HI-PEF) processing (35.5 kV/cm for 1,000 or 300 micros with bipolar 7-micros pulses at 111 Hz; the temperature outside the chamber was always < 40 degrees C) on microbial shelf life and quality-related parameters of whole milk were investigated and compared with traditional heat pasteurization (75 degrees C for 15 s), and to raw milk during storage at 4 degrees C. A HIPEF treatment of 1,000 micros ensured the microbiological stability of whole milk stored for 5 d under refrigeration. Initial acidity values, pH, and free fatty acid content were not affected by the treatments; and no proteolysis and lipolysis were observed during 1 wk of storage in milk treated by HIPEF for 1,000 micros. The whey proteins (serum albumin, beta-lactoglobulin, and alpha-lactalbumin) in HIPEF-treated milk were retained at 75.5, 79.9, and 60%, respectively, similar to values for milk treated by traditional heat pasteurization.
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PMID:Comparative study on shelf life of whole milk processed by high-intensity pulsed electric field or heat treatment. 1650 84

In this paper, the interaction between 2-sulfophenylazo-rhodanine and protein was investigated by Rayleigh light-scattering technique. Based on this, a novel method for the determination of protein was developed. The effects of different conditions, such as acidity and media, were investigated thoroughly, and the optimum conditions were confirmed. Bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion, which is introduced into the protein determination, markedly increased the sensitivity of the system by changing the microenvironment. In pH 2.80 Britton-Robinson buffer solution in the presence of AOT microemulsion, the detection limits of bovine serum albumin, human serum albumin, ovalbumin, and gamma-globulin are 5.4, 4.5, 9.8, and 10.1 ng/mL, respectively. The method developed in this paper has been applied to the determination of protein in milk powder with satisfactory results.
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PMID:Determination of protein in milk powder using 2-sulfophenylazo-rhodanine as a probe by the enhanced resonance Rayleigh light-scattering technique. 1704 87

Tributyltin (TBT) compound is one of the main components of antifouling paint for boats and ships. The interaction of TBT compound and bovine serum albumin (BSA) was investigated by ultraviolet, fluorescence and circular dichroism (CD) spectra. The influences of concentration, acidity and organic solvent were also studied. The results showed that the interaction of TBT and BSA was dual, showing not only the hydrophobic actions of butyl groups but also the coordination action of tin cation with BSA molecule, which resulted in the exposures of aromatic amino acids residues of tryptophane and tyrosine in BSA molecule, the destruction of BSA secondary structure, the decrease in alpha-helix content, and the transformation of the conformation.
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PMID:[Interaction of tributyltin (TBT) compound and bovine serum albumin (BSA)]. 1751 63

In polyethylene glycol 2000 (PEG)-(NH4)2SO4-edible pigment two-phase aqueous systems, the spectroscopic behaviour of the complexes of edible pigment and human serum albumin in PEG phase was investigated. Effects of different acidity, quantities of PEG and salt, reaction time, and coexistent matter on the determination of systems were discussed. Experimental results show that compared to BS spectra, the maximum wavelength of the complex of human serum albumin shifted to the red by 13 nm in buffer solution at pH 8, the maximum binding number of 40 was measured by molar ratio method, and the apparent molar absorptivity was 9.4 x 10(4) L x mol(-1) x cm(-1). The linear range was 0-21.07 mg x L(-1). With different surfactant, the interaction mechanism of protein and edible pigment was discussed.
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PMID:[The spectroscopic study on the interaction between edible pigment and human serum albumin in two-phase aqueous systems]. 1751 68

The interaction between bovine serum albumin (BSA) and Fe(III)-tartrate complexes ([Fe(III)(tar)(H(2)O)(3)](-) and [Fe(III)(tar)(2)](5-)) as well as the damage of BSA in the presence of Fe(III)-tartrate complexes under ultrasonic irradiation was studied by UV-vis and fluorescence spectra. In addition, the influences of ultrasonic irradiation time, Fe(III)-tartrate complex concentration, ionic strength and solution acidity (pH value) were also examined on the damage of BSA. The results showed that the fluorescence quenching of BSA caused by the Fe(III)-tartrate complexes belonged to the static quenching. The BSA and Fe(III)-tartrate complexes interacted with each other mainly through weak interaction and coordinate actions. The corresponding binding association constants (K) and the binding site numbers (n) were calculated. The results were as follows: K(1)=1.67 x 10(3) L mol(-1) and n(1)=0.9699 for [Fe(III)(tar)(H(2)O)(3)](-), K(2)=1.54 x 10(3) L mol(-1) and n(2)=0.8754 for [Fe(III)(tar)(2)](5-). Otherwise, under ultrasonic irradiation the BSA molecules were obviously damaged by the Fe(III)-tartrate complexes. The damage degree rose up with the increase of ultrasonic irradiation time, Fe(III)-tartrate complex concentration, pH value and ionic strength. And that, [Fe(III)(tar)(H(2)O)(3)](-) exhibited higher sonocatalytic activity in a way than [Fe(III)(tar)(2)](5-).
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PMID:Investigation on damage of BSA molecules under irradiation of low frequency ultrasound in the presence of FeIII-tartrate complexes. 1870 48


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