scholarly journals Self-association of unconjugated bilirubin-IX α in aqueous solution at pH 10.0 and physical-chemical interactions with bile salt monomers and micelles

1979 ◽  
Vol 179 (3) ◽  
pp. 675-689 ◽  
Author(s):  
M C Carey ◽  
A P Koretsky
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Bile Salt ◽  
Bile Salts ◽  
Sodium Dodecyl ◽  
Chemical Properties ◽  
Critical Micellar Concentration ◽  
Solvent Mixtures ◽  
Physical Chemical ◽  
Self Association

Spectrophotometric measurements of bilirubin-IX alpha in water and in aqueous/organic solvent mixtures at pH 10.0 as a function of bilirubin-IX alpha concentration (approx. 0.6–400 microM) are consistent with the formation of dimers (KD - 1.5 microM) in dilute (less than 10 microM) aqueous solution and further self-aggregation to multimers at higher concentrations. Added urea (to 10M) and increases in temperature (to 62 degrees C) obliterate the dimer-multimer transition at 10 microM, but added NaCl (to 0.30 M) promotes strong aggregation of dimers over a narrow concentration range, suggesting a ‘micellization’ phenomenon. Concentrations of dioxan or ethanol greater than 60% (v/v) in water were required to obtain the absorption spectrum of bilirubin-IX alpha monomers, suggesting that both hydrophobic and electrostatic (pi-orbital) interactions are involved in stabilizing the dimeric state in water. Micellar concentrations of sodium dodecyl sulphate induced spectrophotometric shifts in the dimer absorption spectrum of bilirubin-IX alpha consistent with progressive partitioning of bilirubin-IX alpha monomers into a relatively non-polar region of the micelles and allowed a deduction of the apparent critical micellar concentration that closely approximated the literature values. The pattern of bilirubin IX alpha association with bile salts is complex, since the absorption spectrum shifts hypsochromically below and bathochromically above the critical micellar concentration of the bile salts. Consistent with these observations, bilirubin IX alpha appears to bind to the polar face of bile salt monomers and to the polar perimeter of small bile salt micelles. At higher bile salt concentrations some-bilirubin-IX alpha monomers partition into the hydrophobic interior of the bile salt micelles. Our results suggest that under physiological conditions the natural conjugates of bilirubin-IX alpha may exhibit similar physical chemical properties in bile, in that dimers, highly aggregated multimers and bile salt-associated monomers may co-exist.

Hepatic bile flow

1984 ◽  
Vol 64 (4) ◽  
pp. 1055-1102 ◽  
Author(s):  
R. C. Strange
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Critical Micellar Concentration ◽  
Canalicular Membrane ◽  
Receptor Proteins ◽  
Subcellular Organelles ◽  
Golgi Bodies ◽  
Initial Event

The hepatocyte is a polar cell that can remove a variety of molecules from blood and excrete them into bile. This review is primarily concerned with the mechanism of transport of the principal anions--the bile salts--across the sinusoidal membrane, their passage through the cell, and excretion across the canalicular membrane. Clearly much of this process is poorly understood, but the study of the membrane stages should be facilitated by the ability to prepare purified sinusoidal and canalicular membrane vesicles. For example, the relative importance of albumin-binding sites as well as the putative bile salt receptor proteins can be better assessed. It seems likely that although the interaction of bile salts with receptor proteins is important, it is an initial event that puts the bile salt in the correct place for uptake to occur. The driving force for uptake is the Na+ gradient created across the basolateral membrane by the activity of the Na+-K+-ATPase. Within the cell, various modes of transport have been suggested. Several authors emphasize the importance of protein binding of bile salts, either because of their presumed ability to maintain the concentration of these anions in the hepatocyte below their critical micellar concentration or because of their putative role in transport. It is important to understand these aspects of the role of cytosolic proteins for several reasons. Knowledge of the true concentration of free bile salt within the cell should allow estimation of whether the electrochemical gradient is sufficient for bile salts to accumulate in bile without the need for active transport of molecules from the cell into the canaliculus. The compartmental model described by Strange et al. (153) offers one theoretical way of determining the concentration of free bile salt, although the problems inherent in studying amphipath binding to the membranes of subcellular organelles (31) require that the model be reevaluated by the hygroscopic-desorption method. The second role suggested for the cytosolic bile salt-binding proteins is as transport proteins. As discussed in section VI, I think it is unlikely that the proteins identified so far act in this way, and it is more likely that movement occurs by diffusion in free solution. It is also important to determine the possible involvement of subcellular organelles such as Golgi bodies. Little is known of their role in the transport of bile salts or indeed where bile salt micelles are formed.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Physical-chemical properties of C-phycocyanin isolated from an acido-thermophilic eukaryote, Cyanidium caldarium

1975 ◽  
Vol 147 (1) ◽  
pp. 63-70 ◽  
Author(s):  
O H Kao ◽  
M R Edwards ◽  
D S Berns
Keyword(s):  
Absorption Spectrum ◽  
High Temperature ◽  
Amino Acid ◽  
Ph Dependence ◽  
Chemical Properties ◽  
Sedimentation Velocity ◽  
Subunit Structure ◽  
Cyanidium Caldarium ◽  
Eukaryotic Alga ◽  
Physical Chemical

C-Phycocyanin from an acido-thermophilic eukaryotic alga, Cyanidium caldarium, was characterized with respect to subunit structure, absorption spectrum and fluorescence properties and was found to be similar to C-phycocyanins from mesophilic sources. The pH-dependence of fluorescence polarization and the changes in sedimentation velocity as a function of pH, concentration and temperature indicate the presence of extremely large amounts of unusually stable 19S aggregates. It was not possible to disaggregate this phycocyanin completely to monomer under normal conditions. The amino acid composition is similar to that of phycocyanins from other thermophilic and halophilic sources. The isoelectric point of this C-phycocyanin was 5.11, an unusually high value. The properties of this C-phycocyanin suggest an increase in protein stability as its mode of adaptation to the environmental stress of high temperature.

The Effects of Bile Salts on Some Coagulation Components and Related Enzymes

1972 ◽  
Vol 27 (03) ◽  
pp. 594-609 ◽  
Author(s):  
A. M Engel ◽  
B Alexander
Keyword(s):  
Platelet Aggregation ◽  
Bile Salt ◽  
Salt Concentration ◽  
Bile Salts ◽  
Direct Action ◽  
Critical Micellar Concentration ◽  
The Other ◽  
Salt Mixture ◽  
Induced Aggregation ◽  
Activator Complex

SummaryCertain purified bile salts, individually or in a mixture, profoundly affect - either inhibiting or enhancing - the esterolytic activities of thrombin, trypsin, and plasmin, the clotting activity of thrombin, and caseinolysis by trypsin. They also promote SK-induced fibrinolysis and impair FI clottability. These effects are directly related to bile salt concentration but not to the critical micellar concentration.A very unusual effect was observed with deoxycholate and FI : besides inhibiting FI clottability, the salt induces spontaneous gelation. In addition, it binds strongly to the protein, as has been already reported for another plasma protein, albumin, and to a lesser degree, to alpha- and beta-globulins.Noteworthy is the fact that activation of pancreatic juice trypsinogen by thrombin also was increased by prior thrombin exposure to the salts. On the other hand, thrombin-induced platelet aggregation was slightly inhibited by the bile salt mixture, which, when added to PRP moderately inhibited the ADP-induced aggregation. No effect was observed on the conversion of F II in plasma via the thromboplastic mechanism when deoxycholate, or cholate, or glycocholate was added to the system.It is postulated that the bile salt mixture enhances SK-induced fibrinolysis by direct action, either on SK, or on the SK-activator complex, attributable to the detergent properties of the salts.The physiologic and pathologic implications of our results with respect to hemostasis and pancreatitis are discussed.

scholarly journals Activated biochar derived from pomelo peel as a high-capacity sorbent for removal of carbamazepine from aqueous solution

RSC Advances ◽  
2017 ◽  
Vol 7 (87) ◽  
pp. 54969-54979 ◽  
Author(s):  
Dezhi Chen ◽  
Shasha Xie ◽  
Caiqin Chen ◽  
Hongying Quan ◽  
Li Hua ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
High Capacity ◽  
Chemical Properties ◽  
Pomelo Peel ◽  
Activated Biochar ◽  
Physical Chemical

In recent years, the application of biochar to remove contaminants from aqueous solutions has become interesting due to favorable physical/chemical properties and abundant feedstocks.

scholarly journals Biliary protein output by isolated perfused rat livers. Effects of bile salts

1983 ◽  
Vol 210 (2) ◽  
pp. 549-557 ◽  
Author(s):  
S G Barnwell ◽  
P P Godfrey ◽  
P J Lowe ◽  
R Coleman
Keyword(s):  
Plasma Membrane ◽  
Bile Salt ◽  
Bile Salts ◽  
Serum Proteins ◽  
Critical Micellar Concentration ◽  
Rapid Decline ◽  
Perfusion Medium ◽  
Rat Serum ◽  
Membrane Enzymes ◽  
Rat Livers

The output of proteins into bile was studied by using isolated perfused rat livers. Replacement of rat blood with defined perfusion media deprived the liver of rat serum proteins (albumin, immunoglobulin A) and resulted in a rapid decline in the amounts of these proteins in bile. When bovine serum albumin was incorporated into the perfusion medium it appeared in bile within 20 min and the amount in the bile was determined by the concentration of the protein in the perfusion medium. The use of a defined perfusion medium also deprived the livers of bile salts and the amounts of these, and of plasma-membrane enzymes [5′-nucleotidase (EC 3.1.3.5) and phosphodiesterase I], in bile declined rapidly. Introduction of micelle-forming bile salts (taurocholate or glycodeoxycholate) to the perfusion medium 80 min after liver isolation markedly increased the output of plasma-membrane enzymes but had no effect on the other proteins. The magnitude of this response was dependent on the bile salt used and its concentration in bile; there was little effect on plasma-membrane enzyme output until the critical micellar concentration of the bile salt had been exceeded in the bile. A bile salt analogue, taurodehydrocholate, which does not form micelles, did not produce the enhanced output of plasma-membrane enzymes. This work supports the view that the output of plasma-membrane enzymes in bile is a consequence of bile salt output and also provides evidence for mechanisms by which serum proteins enter the bile.

scholarly journals Spectrophotometric determination of the critical micellar concentration of bile salts using bilirubin monoglucuronide as a micellar probe. Utility of derivative spectroscopy

1988 ◽  
Vol 252 (1) ◽  
pp. 275-281 ◽  
Author(s):  
W Spivak ◽  
C Morrison ◽  
D Devinuto ◽  
W Yuey
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Sodium Taurocholate ◽  
Critical Micellar Concentration ◽  
Relative Energy ◽  
Bile Pigment ◽  
Sharp Change ◽  
Derivative Spectroscopy ◽  
Invasive Method ◽  
Sudden Decrease

We have developed a simple biologically non-invasive method for determining the critical micellar concentration (CMC) of bile salts using pure naturally occurring bilirubin IX alpha monoglucuronide (BMG), an important bile pigment present in virtually all mammalian biles. This methodology employs visible absorbance spectroscopy of BMG in bile salts over a range of bile salt concentrations that include the reported CMC. Using 100 microM-BMG in 0.4 M-imidazole buffer at pH 7.8, we calculated that the CMC for sodium taurochenodeoxycholate is between 2.5 and 3.0 mM based on: (1) an abrupt change in lambda max. in this concentration range, (2) a precipitous decrease in the amplitude of the absorbance shoulder at 450 nm, (3) a sudden decrease in the second derivative absorbance of BMG at 400 nm and an increase in absorbance at 470 nm, (4) a sharp change in the 4th derivative absorbance at 375 and 395 nm. In contrast, sodium taurocholate, a bile salt that reportedly does not have a CMC but continuously self-associates over a wide concentration range, exhibited none of these changes. The use of derivative spectroscopy enhances the ability to detect the CMC changes and also indicates the number of BMG species in solution and their relative energy states.

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