THE BINDING OF ETHACRYNIC ACID TO BOVINE SERUM ALBUMIN

1967 ◽  
Vol 45 (9) ◽  
pp. 1433-1443 ◽  
Author(s):  
Edward Ronwin ◽  
Anthony G. Zacchei

Studies with 14C-labelled ethacrynic acid indicated that this potent diuretic binds to the albumin fraction of plasma protein. An investigation of the variation of molar binding as a function of the molar concentration ratio revealed that a mole of bovine serum albumin can bind 4 moles of ethacrynic acid strongly (probably irreversibly) and approximately 12 moles reversibly at pH 7.4. Further, it appears that the protein could accommodate a maximum of approximately 16 reversibly bound moles of ethacrynic acid at this pH. Efforts to determine the chemical identity of specific binding sites did not allow positive assignments.

Author(s):  
SHAMPA CHATTERJEE ◽  
T. S. SRIVASTAVA

The binding of meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (T4CPP), meso-tetrakis[3-(carboxymethyleneoxy)phenyl]porphyrin (T3CPP) and meso-tetrakis[3,4-bis(carboxymethyl-eneoxy)phenyl]porphyrin (T3, 4BCPP) with bovine serum albumin (BSA) at pH 7.4 has been studied at 420 nm in detail. The results show hypochromicity along with a red shift in the Soret band of the porphyrins. This suggests that these porphyrins bind to BSA as monomers. Further analysis of these data supports the non-interactive binding of T4CPP and T3CPP with BSA and the cooperative binding of T3, 4BCPP with BSA. These binding data have been interpreted in terms of one specific binding site and several non-specific binding sites on BSA for the porphyrins. The absorption spectral changes of the porphyrins between 400 and 450 nm when titrated with BSA suggest that there is another specific binding site on BSA for the porphyrins. These two specific binding sites have also been supported by circular dichroism (CD) studies. The absorption spectral and CD studies on the interactions of the porphyrins with BSA further suggest that these interactions are dependent on the number and configuration of substituents in the phenyl groups of the porphyrins. The contact energy transfer from the aromatic amino acid residues tryptophan and tyrosine of BSA to the porphyrins in the BSA–porphyrin complexes has also been studied using fluorescence spectroscopy. These energy transfer data show the energy transfer from tryptophan to the porphyrins for their binding to site I of BSA and from tyrosine to the porphyrins for their binding to site II of BSA. Unfolding studies of the BSA–porphyrin systems indicate that the tertiary structure is essential for the binding of the porphyrins. A correlation between the accumulation of99 mTc -labelled T4CPP and T3, 4BCPP in tumour tissue and their binding at site II of BSA is possible. The interaction of the porphyrins can also be used as a model for mitochondrial interactions.


1983 ◽  
Vol 212 (2) ◽  
pp. 249-257 ◽  
Author(s):  
M J Imber ◽  
S V Pizzo

These studies explore the role of carbohydrate recognition systems and the direct involvement of terminal alpha 1-3-linked fucose in the clearance of lactoferrin from the murine circulation and in the specific binding of lactoferrin to receptors on murine peritoneal macrophages. As previously reported, radiolabelled lactoferrin cleared very rapidly (t1/2 less than 1 min) after intravenous injection into mice. However, competing levels of ligands specific for the hepatic galactose receptor (asialo-orosomucoid), the hepatic fucose receptor (fucosyl-bovine serum albumin), and the mononuclear-phagocyte system pathway recognizing mannose, N-acetylglucosamine and fucose (mannosyl-, N-acetylglucosaminyl- and fucosyl-bovine serum albumin) did not block radiolabelled lactoferrin clearance in vivo or binding to mouse peritoneal macrophage monolayers in vitro. Almond emulsin alpha 1-3-fucosidase was used to prepare defucosylated lactoferrin in which 88% of the alpha 1-3-linked fucose was hydrolysed. No difference in clearance or receptor binding was observed between radiolabelled native and defucosylated lactoferrin. Fucoidin, a fucose-rich algal polysaccharide, completely inhibits the clearance in vivo and macrophage binding in vitro of lactoferrin. This effect, however, is probably not the result of competition for binding to the fucose receptor, since gel-filtration studies demonstrated formation of a stable complex between lactoferrin and fucoidin. The present results indicate that the lactoferrin-clearance pathway is distinct from several pathways mediating glycoprotein clearance through recognition of terminal galactose, fucose, N-acetylglucosamine or mannose. Furthermore, alpha 1-3-linked fucose on lactoferrin is not essential for lactoferrin clearance in vivo or specific binding to macrophage receptors in vitro.


1992 ◽  
Vol 103 (2) ◽  
pp. 565-570
Author(s):  
V. Leick

Receptor-mediated binding of leukocyte chemotactic peptide, N-formylMet-Leu-Phe (fMLP), occurs in the ciliated protozoon Tetrahymena thermophila. In vivo labelling of the cells with N-formylMet-Leu-[3H]Phe ([3H]fMLP) shows that the cells bind the ligand with high affinity (KD = 4 × 10(−9) M to 1 × 10(−8) M). Moreover, Scatchard transformations of the binding data show that there are about 5 × 10(5) binding sites per cell on the cell surface. Two fluorescent derivatives of leukocyte chemotactic peptide, N-dansylMet-Leu-Phe (dansMLP) and N-formylMet-Leu-Phe-(N-dansyl-)Lys (fMLPdanLys) compete for the N-formylMet-Leu-Phe (fMLP) binding sites on the cell surface. Moreover, both derivatives have retained significant chemoattracting potentials. Fluorescence from dansMLP, but not from fMLPdansLys and dansyl-beta-endorphin, is internalized preferentially into small vesicles. The differences may, however, reflect that the fluorescence from the dansyl group is strongly quenched by a hydrophilic microenvironment when using the two latter peptide derivatives. In contrast, the dansyl group from dansMLP must be assumed to be embedded in a hydrophobic microenvironment in the vesicular membrane or membrane protein. Rhodamine-labelled bovine serum albumin, egg albumin and cytochrome c as well as dansylated bovine serum albumin, which are poor chemoattractants, are preferentially seen to be internalized into large vesicles (food vacuoles).


1995 ◽  
Vol 269 (5) ◽  
pp. H1514-H1521 ◽  
Author(s):  
M. A. Katz ◽  
M. L. La Marche

Albumin reduces capillary hydraulic conductance (Lp) even at low concentrations. To determine if part of this barrier protective effect might be extracellular, we studied the effects of bovine serum albumin (BSA) on Lp of self-assembled basement membrane (Matrigel). Lp with tris(hydroxymethyl)aminomethane (Tris) buffer superfusate was stable at 1.77 +/- 0.22 x 10(-5) (SE) cm.s-1.cmH2O-1 over several hours. At 0.1 g/dl BSA, experimental/control (Tris) Lp fell to 83.1 +/- 6.0% (2P < 0.025), with decreases to 72.4 +/- 3.7% at 1 g/dl (2P < 0.005), 45.3 +/- 5.1% at 2.5 g/dl (2P < 0.001), and 45.0 +/- 4.8% at 4.0 g/dl (2P < 0.001). In separate experiments, BSA arginine groups were neutralized by 1,2-cyclohexanedione (CHD), and experimental/control Lp values were measured. At 2.5 g/dl, CHD-BSA depressed Lp to 54.4 +/- 4.8%, while unmodified BSA reduced Lp to 40.8 +/- 3.5% of Tris control (2P = 0.05). Finally, soluble arginine at three- and sixfold the arginine in BSA was added to BSA superfusate. For threefold, Lp rose to 120 +/- 8% of BSA level and for sixfold to 129 +/- 9% (2P < 0.05). We conclude that some part of the albumin protective effect is very likely due to consequences on extracellular matrix and that at least 18-22% of this effect is related to arginine groups on albumin when computed from Lp, and up to 34% when viscosity is taken into account. Membrane-saturable arginine-binding sites can be unbound with arginine, thus nullifying part of the barrier protective effect of BSA.


2007 ◽  
Vol 1774 (11) ◽  
pp. 1359-1369 ◽  
Author(s):  
Paz Sevilla ◽  
José M. Rivas ◽  
Francisco García-Blanco ◽  
José V. García-Ramos ◽  
Santiago Sánchez-Cortés

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Qiaoli Yue ◽  
Tongfei Shen ◽  
Changna Wang ◽  
Chaohui Gao ◽  
Jifeng Liu

The mechanism of the interaction between bovine serum albumin (BSA) and ceftriaxone with and without zinc (II) (Zn2+) was studied employing fluorescence, ultraviolet (UV) absorption, circular dichroism (CD), and synchronous fluorescence spectral methods. The intrinsic fluorescence of BSA was quenched by ceftriaxone in a static quenching mode, which was authenticated by Stern-Volmer calculations. The binding constant, the number of binding sites, and the thermodynamic parameters were obtained, which indicated a spontaneous and hydrophobic interaction between BSA and ceftriaxone regardless of Zn2+. Changes in UV absorption, CD, and synchronous fluorescence spectral data are due to the microenvironment of amide moieties in BSA molecules. In the BSA-ceftriaxone-Zn2+ system, Zn2+ must first interact with ceftriaxone forming a complex, which inhibits BSA binding to ceftriaxone. The present work uses spectroscopy to elucidate the mechanism behind the interaction between BSA and ceftriaxone in the presence and absence of Zn2+. The BSA and ceftriaxone complex provides a model for studying drug-protein interactions and thus may further facilitate the study of drug metabolism and transportation.


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