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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Irradiation with visible light of human serum albumin in aqueous solution at pH 8, in the presence of catalytic amounts of rose bengal or methylene blue, resulted in random oxidation of the histidine residues in the protein under consumption of one mole O2, and release of somewhat less than one proton, per histidine residue degraded. An increase of light absorption at 250 nm was proportional to the amount of oxygen consumed. Bilirubin bound to the oxidized protein showed an increased light absorption at its maximum, 460 nm, and a decreased binding affinity, indicating a conformational change of the protein on oxidation of histidine residues. This change also resulted in a slight perturbation of tyrosine light absorption, corresponding to a shift of the chromophore to more polar surroundings. Further, a sensitized oligomerization of albumin was observed, independent of oxidation of the histidine residues, and not consuming oxygen. Irradiation of a complex of human serum albumin with one molecule of bound bilirubin, in the absence of a sensitizing dye, resulted in a fast, non-oxygen consuming process whereby the light absorption maximum of the pigment was shifted 4 nm towards longer wavelength and part of the bilirubin was converted to a more polar pigment, bound less firmly to the protein. This was followed by a relatively slow oxidation of the pigment under uptake of one mole O2. Parallel photooxidation of the protein carrier could not be detected. It is considered possible that the fast, anaerobic process is operative in phototherapy of hyperbilirubinemia in the newborn. Serum albumin is probably not oxidized during this treatment.
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PMID:Photooxidation of human serum albumin and its complex with bilirubin. 1 94

The binding of sisomicin and streptomycin to human serum albumin was studied in the absence of divalent cations by means of the dialysis method. Hydrophobic bonds between albumin and sisomicin or streptomycin can be excluded by nuclear magnetic resonance measurements. The presence of hydrogen bonds is made unlikely according to the result that the binding of the aminoglycosides decreases with increasing number of OH groups in the aminoglycoside molecule. The pH dependence of protein binding suggests that ionic bonds are involved in the binding of aminoglycosides. On the basis of the concentration dependence of the albumin binding of sisomicin and streptomycin we determined the binding affinities delta F degrees, the binding constants K1, and the maximum number n of aminoglycoside molecules that can be bound by a molecule of albumin in the absence of Ca++ ions. The results were as follows: Sisomicin: delta F degrees = -4189 cal/mole, K1 = 900 1/mole, n = 12; Streptomycin: delta F degrees = 3512 cal/mole, K1 = 300 1/mole, n = 17.
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PMID:Ionic binding of aminoglycosides to human serum albumin in the absence of divalent cations. IV. Effect of structure, ph and concentration. 2 93

Human serum pregnancy-specific beta1-globulin (beta1-GP) was localized in paraffin sections of placenta and chorioepithelioma of the uterus by indirect immunofluorescence. The structures containing beta1-GP but not human serum albumin were regarded as specifically associated with beta1-GP metabolism. Beta1-GP was found in trophoblastic cells of chorion and Langhans cells of chorioepithelioma. Using the immunoautoradiographic method (I131), we only found beta1-GP in sera of patients with trophoblastic tumours: in 74.3% of 35 patients with chorioepithelioma and in 80% of 25 patients with hydatidiform mole and destructive hydatidform mole. The diagnostic and prognostic significance of the immunochemical test for beta1-GP in trophoblastic tumours is discussed.
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PMID:Human pregnancy-specific beta1-globulin and its relation to chorioepithelioma. 5 35

A 17beta-estradiol-6-carboxymethyl-oxime-bovine serum albumin--fluorescein isothiocyanate conjugate is prepared by attaching on the average 11 moles of the fluorescein dye and 24 moles of the steroid hormone to each mole of the protein carrier. This fluorescent estradiol conjugate is used as a tracer to detect estrogen receptor of human mammary cancer cells in frozen sections. The cytochemical findings indicate that mammary carcinomas are composed of heterogeneous populations of receptor-positive and receptor-negative cancer cells in varying proportions and probably should be classified according to the percentages of receptor-positive cells in the cancer cell populations for better correlation with endocrine therapies.
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PMID:Cytochemical study of estrogen receptor in human mammary cancer. 8 Sep 58

We report the equilibrium binding parameters for the interactions of the estrogen analogue diethylstilbestrol (DES) with highly purified rat alpha 1-fetoprotein (AFP) and serum albumin preparations. At 25 degrees C and pH 7.4, an association constant (Ka) of about 1.5 X 10(6)M-1 and 2 sites/mole are measured with the DES-AFP system, whereas for the DES-albumin interaction, we find a Ka of approximately 2 X 10(5)M-1 and about 11 sites/mole of protein. The removal of fatty acids from pure AFP causes a reversible 3 fold increase of the number of DES binding sites; the same delipidation procedure applied to albumin slightly diminishes its DES binding parameters. We also demonstrate the capability of DES to displace competitively estradiol-17 beta (E2) from its high affinity sites on the estrophilic rat AFP. Finally, the binding behaviour of the two serum proteins towards the synthetic estrogen is compared to their interaction with the natural hormones. The physiological and pharmacological relevance of these data is discussed.
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PMID:Ligand properties of diethylstilbestrol: studies with purified native and fatty acid-free rat alpha 1-fetoprotein and albumin. 9 92

Three spin-labeled derivatives of stearic acid and two derivatives of palmitic acid have been used to study the structure of the strong fatty acid binding site of bovine serum albumin. The steroid and indole binding sites have been studied using spin-labeled derivatives of androstol and indole, respectively. Paramagnetic resonance and fluorescence quenching data suggest that the fatty acid, steroid, and indole binding sites may be identical. The mobility of the nitroxyl group at C-8 of palmitic acid bound to albumin at a 1:1 molar ratio is unaffected when the carboxyl group is esterified. When the nitroxyl group is located at C-5 on this acid its motion is detectably increased by esterification of the carboxyl group but the magnitude of this change is small. This result suggests that the carboxyl group may play a minor role in the binding of fatty acids to the strongest fatty acid binding site of albumin. When stearic acid derivatives bearing the nitroxide at C-5, C-12, and C-16 are bound to albumin at a ligand to albumin ratio of 1, the order of mobility at 0-30 degrees is C-16 greater than C-12 congruent to C-5. Although motion at the methyl terminus is always greater than at the COOH terminus in the range 0-60 degrees, a simple monotonic increase in chain motion between the two termini is not observed. Arrhenius plots of the motion parameters for these bound fatty acids show two abrupt changes in slope. The temperature ranges for these changes are 15-23 degrees and 38-45 degrees. These results suggest that when one mole of spin-labeled fatty acid is bound to albumin, the protein undergoes a conformational change in each of these temperature ranges.
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PMID:Bovine serum albumin. Study of the fatty acid and steroid binding sites using spin-labeled lipids. 16 44

Heat-denatured chicken egg white lysozyme and the reduced carboxymethylated maleylated derivative of this protein were found to serve as substrates for rabbit skeletal muscle cyclic AMP-dependent protein kinase. The native form of the protein was not a substrate. Two phosphoryl groups per mole of lysozyme were incorporated in the reaction. It was determined that the phosphoryl moieties were bound to serine 24 and serine 50 in the modified protein. Serine 24 was phosphorylated approximately 3 times as fast as serine 50. Reduced carboxymethylated maleylated derivatives of bovine serum albumin, phosphorylase b, and creatine kinase also served as substrates for the protein kinase whereas their native forms did not. The reduced carboxymethylated maleylated derivative of the inhibitory subunit of troponin was a poorer substrate than the native form of the protein. Maleylated histones F1 and F2b were also poorer substrates than the nonderivatized forms. The significance of these experiments with reference to the specificity of cyclic AMP-dependent protein kinase is discussed.
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PMID:Effect of denaturation on the susceptibility of proteins to enzymic phosphorylation. 16 38

The interaction between valproic acid (VPA) and human serum albumin (HSA) was investigated using the equilibrium dialysis technique under various conditions. Solutions of VPA in HSA (2 x 10(-4) M) were dialyzed against isotonic phosphate buffer at 37 degrees C. Protein and buffer compartments were assayed for VPA by GLC. The free fraction (alpha) of VPA increased from 0.13 at 27 microgram/ml to 0.49 at 103 microgram/ml. Scatchard plots were linear, indicating the existence of one type of binding site. The mean (+/- % SD) number of binding sites per macromolecule was 2.06 +/- 3.7% and the mean (+/- % SD) association constant was 2.69 x 10(4) +/- 15.0% liters/mole. The effects of three anticonvulsants (phenytoin, phenobarbital, and carbamazepine) and four major free fatty acids (FFA) (stearic, palmitic, oleic, and linoleic) on alpha were studied. The free fraction, 0.18, was not affected by phenobarbital (20 and 40 microgram/ml), carbamazepine (10 and 20 microgram/ml) or phenytoin (20 and 40 microgram/ml). Each of the four FFA caused a significant increase in alpha: 19--48% increase at 100 microgram/ml of FFA and 88--118% at 200 microgram/ml.
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PMID:Valproic acid binding to human serum albumin and determination of free fraction in the presence of anticonvulsants and free fatty acids. 36 55

Unselected, consecutive surgical specimens from 120 women with cancer of the breast were subjected to histochemical assay for the presence of estrogen receptor. A fluoresceinated bovine serum albumin--estradiol conjugate was used that linked estradiol at position 17 and contained 5 mol fluorescein and 4 mol estradiol per mole albumin. Simultaneous competitive binding studies with excess unlabeled estradiol, diethylstilbestrol, and the antiestrogen nitromifene citrate were regularly performed. Results were compared to those obtained by the dextran-coated charcoal receptor assay. Three specimens were necrotic, two others thawed, and two lacked sufficient protein for biochemical analysis. One specimen did not contain tumor, and 11 others showed a predominant nuclear staining pattern. Nuclear receptor was not assayed biochemically. Comparison of results in the remaining 101 cases showed agreement in 92%. The precedure is uncomplicated, economical, and could be performed and interpreted in any pathology laboratory.
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PMID:An improved histochemical method for detection of estrogen receptors in mammary cancer. Comparison with biochemical assay. 37 38

Antibodies to adenosine were elicited in rabbits by immunization with bovine serum albumin-adenosine conjugate. The antibodies were purified and fractionated on two affinity columns (Sepharose-oligo(A) and Sepharose-AMP). Two families of antibodies have been obtained. The antibodies purified on the Sepharose-oligo(A) column react with poly(A) while those purified on the Sepharose-AMP column do not, as shown by gel diffusion. The association constants for the binding of Fab fragments or IgG purified on the Sepharose-oligo(A) column and several haptens were deduced from dialysis equilibrium, fluorescence quenching and displacement of AMP-fluorescein conjugate. The antibodies mainly recognize adenine, and the ribose or the phosphate group of (or AMP derivatives) do not play a critical role in the interaction. Thermodynamic parameters for adenosine-Fab fragments complexes have been determined deltaH degrees = 16 kcal/mole and deltaS degrees = - 15 cal. degree-1 mole-1. Circular dichroism studies indicate that about three nucleotide residues penetrate the binding site of Fab fragments.
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PMID:Purification and specificity of antibodies to adenosine. 40 59


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