Albumin sites

Caravan, P, Greenfield, M.T., Li, X., and Sherry, A.D. (2001) The Gd complex of a fatty acid analogue of DOTP binds to multiple albumin sites with variable water relaxivities. Inorganic Chemistry, 40, 6580-6587. 

Phenytoin enters the brain rapidly and is redistributed to other body tissues, including breast miUc and the placenta. It is highly (>90%) protein bound. Phenytoin competes for albumin sites with other highly protein bound drugs. It is essential to know the patient s serum albumin level in interpreting the serum concentrations of phenytoin. Patients with significant renal dysfunction will have altered phenytoin protein binding. Obesity increases the volume of distribution of phenytoin. 

A low hydrogen ion concentration occurs as a result of hyperventilation, in which carbon dioxide is blown off in the lungs. The condition occurs in certain otherwise normal people who hyperventilate as a reaction to stress. A frequent result is a reduced concentration of ionized calcium in the extracellular fluid, the condition of hypocalcaemia. The effect is hypocalcaemic tetany, which consists of involuntary uncoordinated contractions of skeletal muscles and of bizarre subjective sensations and numbness. These symptoms and signs are due to hyperexcitability of peripheral nerve fibres, which fire action potentials spontaneously. The mechanism is that the reduced hydrogen ion concentration results in dissociation of complexes between plasma albumin and hydrogen ions, with a binding of plasma calcium to the albumin sites which are vacated by the hydrogen ions. Hence there is a fall in the concentration of ionized calcium in the extracellular fluid and this results in the nervous hyperexcitability. 

Dougherty, T.J., Sumlin, A.B., Greco, W.R., Weishaupt, K.R., Vaughan, L.A., and Pandey, R.K., The role of the peripheral benzodiazepine receptor in photodynamic activity of certain pyropheophor-bide ether photosensitizers albumin site II as a surrogate marker for activity, Photochem. Photohiol, 76, 91, 2002. 

One limitation of enzyme replacement therapy is the targeting of enzyme proteins to appropriate sites of substrate accumulation. Administration of a cholesterol esterase conjugated to albumin results in the degradation of pathologic cholesterol ester accumulations within the lysosomes of fibroblasts from a patient with cholesterol ester storage disease (246). 

Sulfaphenazole (684) and sulfazamet (685) are both examples of relatively short acting sulfonamides (B-80MI40406) and their antibacterial activity has been tested against Escherichia coli, the former being more effective than the latter. Sulfaphenazole also displaces sulfonyl ureas from protein binding sites on human serum albumin and consequently increases the concentration of the free (active) drug and produces a more intense reaction that may result in hypoglycemia. 

When most lipids circulate in the body, they do so in the form of lipoprotein complexes. Simple, unesterified fatty acids are merely bound to serum albumin and other proteins in blood plasma, but phospholipids, triacylglycerols, cholesterol, and cholesterol esters are all transported in the form of lipoproteins. At various sites in the body, lipoproteins interact with specific receptors and enzymes that transfer or modify their lipid cargoes. It is now customary to classify lipoproteins according to their densities (Table 25.1). The densities are... 

Caeruloplasmin (Cp) is an acute phase glycoprotein with a copper transport function. At least 90% of total plasma copper is bound to Cp with the remaining 10% associated with albumin, histidine and small peptides. Lipid peroxidation requires the presence of trace amounts of transition metals and the copper-containing active site of Cp endows it with antioxidant capacity... 

Direct and indirect competition formats, illustrated in Figure 1, are widely used for both qualitative and quantitative immunoassays. Direct competition immunoassays employ wells, tubes, beads, or membranes (supports) on to which antibodies have been coated and in which proteins such as bovine semm albumin, fish gelatin, or powdered milk have blocked nonspecific binding sites. Solutions containing analyte (test solution) and an analyte-enzyme conjugate are added, and the analyte and antibody are allowed to compete for the antibody binding sites. The system is washed, and enzyme substrates that are converted to a chromophore or fluorophore by the enzyme-tracer complex are added. Subsequent color or fluorescence development is inversely proportionate to the analyte concentration in the test solution. For this assay format, the proper orientation of the coated antibody is important, and anti-host IgG or protein A or protein G has been utilized to orient the antibody. Immunoassays developed for commercial purposes generally employ direct competition formats because of their simplicity and short assay times. The price for simplicity and short assay time is more complex development needed for a satisfactory incorporation of the label into the antibody or analyte without loss of sensitivity. 

We used an anti-DNA antibody as an exploratory model system. The antibody was monoelonal from mouse sourees and its subelass was IgM. Mouse IgG (MW 1.5 x 10 Da) and IgM (MW 9 X 10 Da) antibodies from normal plasma, and bovine serum albumin were used for the eontrol measurements. To prevent the nonspeeilie adsorption of proteins to the uneovered, bare Au site in the modified eleetrode surfaee, the DNA-modified eleetrode prepared by the standard proeedure was further treated with aqueous 2-mercaptoethanol solution and was used for the measurements. 

Patwardhan, A.V. and Ataai, M.M., Site accessibility and the pH dependence of the saturation capacity of a highly cross-linked matrix. Immobilized metal affinity chromatography of bovine serum albumin on Chelating Superose, /. Chromatogr. A, 767, 11, 1997. 

Because of the presence of anionic sites on the endothelium and on the glycocalyx layer, anionic macromolecules show a significantly slower rate of extravasation compared with neutral and cationic macromolecules. Kern and Swanson [39] found a threefold increase in the permeability of the pulmonary vascular system to cationic albumin, compared with native albumin of the same molecular weight and hydrodynamic radius. 

The N-terminal peptide fragment of des-angiotensinogen Val-Ile-His-Asn contains two strongly hydrophobic amino acid residues on the N-terminal site of His-3. The potentiometric data have shown that the NiH.2L complex with this albumin-like sequence is more than two orders of magnitude more stable than the respective complex with Gly-Gly-His.1744 The NMR-based molecular structure has shown that the side chains of Val-1 and lie-2 form a well-ordered hydrophobic fence (Figure 21) shielding one side of the coordination plane from the bulk of... 

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