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Query: UMLS:C0027960 (mole)
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Binding of free fatty acid (FFA) to human serum albumin (HSA) was studied by 1H-NMR spectroscopy. Addition of FFA to defatted HSA at a mole ratio (FFA/HSA) up to 4 caused a small change in the NMR spectrum of HSA. The integrated intensity of sharp signals of the histidine C2 proton region of HSA decreased as the mole ratio was increased from 0 to 4 for both medium chain (lauric acid) and long chain (palmitic acid, stearic acid, and oleic acid) FFA's. By contrast, when the mole ratio was increased above 4, several histidine C2 proton signals coalesced and sharpened. Therefore, the HSA molecule appears to have a different conformation on binding with more than 4 FFA molecules, which allows increased local motions of HSA. By analyzing the NMR difference spectra of HSA with various amounts of FFA, the conformational change of HSA was investigated in more detail. The difference spectrum between [HSA + 2FFA] and [HSA + FFA] was almost the same as the difference spectrum between [HSA + FFA] and [HSA], which suggests that one primary site binds a pair of FFA molecules. These results are consistent with those of a spectroscopic study with polyene fatty acids (Berde, C.B., et al. (1979) J. Biol. Chem. 254, 391-400). The existence of a bimolecular complex of FFA molecules in aqueous solution may facilitate this type of binding. Similarly, it was found that the third and fourth FFA molecules were bound to a secondary site on HSA, because the difference spectrum between [HSA + 4FFA] and [HSA + 3FFA] was nearly equal to the difference spectrum between [HSA + 3FFA] and [HSA + 2FFA]. Further addition of FFA resulted in a drastic spectral change of HSA. The NMR difference spectrum between HSA solutions with perdeuterated FFA and those with undeuterated FFA gave the 1H-NMR spectra of FFA molecules bound to HSA. Titration of FFA revealed that, in the binding to the primary site of HSA, the carboxyl group of FFA is tightly bound to the protein, whereas the methyl group is not so firmly bound. In contrast, in the binding to low affinity sites, the methyl group is bound to HSA as tightly as other portions of the molecule.
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PMID:1H-NMR study on the interactions of human serum albumin with free fatty acid. 357 Nov 85

13C NMR chemical shift and intensity results for a series of carboxyl 13C-enriched saturated fatty acids (8-18 carbons) bound to bovine serum albumin (BSA) are presented as a function of increasing fatty acid (FA)/BSA mole ratio. Spectra for long-chain (greater than or equal to 12 carbons) FA X BSA complexes exhibited up to five FA carboxyl resonances, designated a, b, b', c, and d. Only three resonances (peaks b, b', and d) were observed below 3:1 FA X BSA mole ratio, and at greater than or equal to 3:1 mole ratio, two additional resonances were observed (peaks c and a). In a spectrum of 5:1 stearic acid X BSA complexes, peaks b, b', and d each represented approximately one-fifth, and peak c approximately two-fifths, of the total FA carboxyl intensity. Plots of total carboxyl/carbonyl intensity ratio as a function of FA X BSA mole ratio were linear up to 7-9 mole ratio. Deviation from linearity at mole ratios greater than or equal to 7 was accompanied by the detection of crystalline unbound FA (as 1:1 acid/soap) by X-ray diffraction. In contrast to long-chain FA X BSA complexes, 13C NMR spectra of octanoic acid X BSA complexes yielded only one FA carboxyl resonance (peak c) at FA X BSA mole ratios between 1 and 20. We conclude: peaks b, b', and d represent FA bound to three individual high affinity (primary) long-chain FA binding sites on BSA; peak c represents FA bound to several secondary long-chain (or primary short-chain) FA binding sites on BSA; peak a represents long-chain FA bound to an additional lower affinity binding site. We present a model that correlates the observed 13C NMR resonances with individual binding site locations predicted by a recent three-dimensional model of BSA.
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PMID:Carbon 13 NMR studies of saturated fatty acids bound to bovine serum albumin. I. The filling of individual fatty acid binding sites. 361 Oct 99

Synthetic peptides derived from human fibrin were unidirectionally conjugated to three carrier proteins (bovine serum albumin, bovine alpha-lactalbumin, and keyhole limpet hemocyanin) by a method that employs N-succinimidyl bromoacetate. This heterobifunctional crosslinking reagent was prepared with a 79% yield in gram quantities from inexpensive starting materials. With this reagent, carrier proteins were first bromoacetylated, then reacted with the thiol groups of cysteine-containing peptides. The extent of peptide conjugation was assessed by amino acid analysis after acid hydrolysis, which liberated 1 mol of S-carboxymethylcysteine for each mole of thioether linkage between peptide and protein. The results of several conjugation experiments indicated that the efficiency of peptide incorporation ranged between 22 and 37% based on the recovery of S-carboxymethylcysteine relative to lysine. When the conjugates were used as immunogens, the S-carboxymethyl linkage was not antigenic in comparison with the S-maleimidobenzoyl linkage, even though their antipeptide immunoreactivities were similar.
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PMID:Preparation of peptide-protein immunogens using N-succinimidyl bromoacetate as a heterobifunctional crosslinking reagent. 371 62

The ionization behavior of cholic acid, deoxycholic acid, and chenodeoxycholic acid in a variety of physiologically important molecular environments was studied using 13C NMR spectroscopy. The apparent pKa of the carboxyl group was determined from titration curves obtained from the dependence of the carboxyl carbon chemical shift on pH. Using 90% 13C isotopic substitution of the carboxyl carbon, a complete titration curve was obtained for cholate at a concentration below its critical micelle concentration and solubility limit in water. Incorporation of 12 mole % bile acid into mixed micelles with its taurine conjugate prevented precipitation of the unconjugated bile acid, and titration curves for cholic, deoxycholic, and chenodeoxycholic acids in the mixed micelles were obtained. The apparent pKa was also determined for 13C-enriched bile acids complexed with bovine serum albumin and in egg phosphatidylcholine vesicles. For monomers, micelles, and BSA complexes of all three bile acids and for deoxycholic and chenodeoxycholic acid in vesicles, one magnetic environment was observed. In contrast, two environments, both titratable, were detected for cholic acid in phosphatidylcholine vesicles. The apparent pKa's of the bile acids in the different environments ranged from 4.2 to 7.3. At pH 7.4, as monomers or bound to albumin, the bile acids were fully ionized, but when associated with phosphatidylcholine vesicles they were only partially ionized. In addition, aspects of the molecular motion and relative hydrophobicity of the bile acid carboxyl group in the environments studied were discerned from chemical shift, line-width, and lineshape data.
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PMID:The ionization behavior of bile acids in different aqueous environments. 373 30

The possibility that bilirubin can diffuse through lipid bilayers is investigated with liposomes prepared from dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylcholine (egg PC) with 22 mole percent cholesterol, and a lipid extract preparation from N115 neuroblastoma cells. Liposomes were prepared with internalized bilirubin and bovine or human serum albumin, and bilirubin efflux into an exogenous solution of human serum albumin was measured. Efflux from DPPC liposomes was significantly higher above the phase transition temperature than below it. This change was dependent on the lipid undergoing a phase transition and could not be accounted for by 6 K change in temperature. Maximum bilirubin efflux from egg PC-cholesterol liposomes was found to depend on the relative internal and external albumin pools, suggesting an equilibrium distribution of bilirubin between them. These observations demonstrate that bilirubin can diffuse freely through these lipid membranes.
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PMID:Bilirubin diffusion through lipid membranes. 375 60

Erythromycin binding to human serum albumin and to alpha 1-acid glycoprotein was measured under conditions of binding equilibrium. At therapeutical concentrations of erythromycin the binding to albumin is not saturable. The fraction of total erythromycin bound to alpha 1-acid glycoprotein is proportionally related to the protein concentration and is bound to a single class of binding sites with an apparent association constant Ka = 0.16 X 10(6) M-1 (38 degrees). About one mole of erythromycin is bound per mole of alpha 1-acid glycoprotein. The binding affinity can be enhanced and vice versa lowered by increasing the concentrations of NaCl and urea, respectively. The semilogarithmic plot of bound/free ratios vs log concentration of NaCl or urea exhibits linear relationships. Erythromycin binding can be competitively inhibited by mersalyl (Ki = 11-16 microM) but not by other SH-reagents or by neuraminidase treatment. A marked reduction of erythromycin binding to alpha 1-acid glycoprotein is seen with dithiothreitol. alpha 1-acid glycoprotein is the main erythromycin binding protein in human serum.
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PMID:The binding protein of erythromycin in human serum. 395 99

The transfer of hemin from one protein to another is an event biologically important for the conservation of heme iron. Hemin entering the circulation (or added to serum) is mainly bound by albumin and then transferred to hemopexin [Morgan, W.T., Liem, H.H., Sutor, R.P., & Muller-Eberhard, U. (1976) Biochim. Biophys. Acta 444, 435-445], and we are now investigating which mechanisms may be operative in enhancing this process. The presence of imidazole has been demonstrated to accelerate hemin transfer from albumin to hemopexin [Pasternack, R.F., Gibbs, E.J., Hoeflin, E., Kosar, W.P., Kubera, G., Skowronek, C. A., Wong, N.M., & Muller-Eberhard, U. (1983) Biochemistry 22, 1753-1758]. The present work is an examination of the effect of the reduction of albumin-bound hemin on the rate of its transfer to hemopexin. Hemin (HmIII., ferriprotoporphyrin IX) was reduced to HmII (ferroprotoporphyrin IX) by the addition of sodium dithionite under argon. The reduction kinetics of HmIII to HmII were studied separately in the two complexes: with human serum albumin (HSA), which binds up to 20 mol of heme/mol (the first mole with K congruent to 10(8)), and with hemopexin (HHx), which binds heme equimolarly (K congruent to 10(13)). The rate of reduction of HmIII to HmII on HSA was first order over several half-lives and linearly dependent on [S2O4(2-)]1/2. At [HSA]0/[HmIII] = 3, the kobsd was (5 X 10(-3) + 0.75[S2O4(2-)]1/2, and with [HSA]/[HmIII] approximately 25, the kobsd was (2 X 10(-3)) + 0.25[S2O4(2-)]1/2. The reduction of HmIII to HmII on human hemopexin (HHx) is much more rapid with kobsd = (2.5 X 10(3))[S2O4(2-)]1/2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Kinetics of hemoprotein reduction and interprotein heme transfer. 407 7

An enzyme-linked immunosorbent assay (BA-ELISA) involving use of biotin-labeled anti-rabbit IgG and avidin-labeled horseradish peroxidase was developed for the measurement of O6-methyl-2'-deoxyguanosine (O6-MedGuo). Up to 5 micrograms of methylated DNA was enzymatically hydrolyzed, and the extent of inhibition of binding of immobilized O6-MedGuo-bovine serum albumin to rabbit anti-O6-MedGuo was measured. Fifty percent inhibition of antigen-antibody binding was achieved with 2.5 pmole of of O6-MedGuo. Separation of O6-MedGuo from unmodified nucleosides by high-performance liquid chromatography (HPLC-BA-ELISA) allowed detection of 700 fmole O6-MedGuo in 1 mg of DNA. Among the tobacco-related carcinogens, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is one of the most potent. In F344 rats it induces nasal cavity, lung and liver tumors. Four hours after a single IV injection of NNK to F344 rats (87 mg/kg body weight), O6-MedGuo was present in target organs (mumole O6-MedGuo/mole dGuo) (nasal mucosa, 219; lung, 13.2; and liver, 34.5) but was not detectable in nontarget organs. F344 rats receiving daily IP injections of NNK (40 mg/kg body weight) for 14 days were sacrificed 24 hr after the last injection. The levels of (O6-Medguo/dGuo) were 7.9 and 11.4 mumole/mole in the nasal mucosa and lung, respectively. In the liver no O6-MedGuo was detected, but 1050 mumole of 7-MeGua/mole Gua was measured by HPLC-fluorimetry. No DNA methylation was observed in the nasal mucosa or liver of F344 rats treated with the nicotine-derived carcinogen N'-nitrosonornicotine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Study of DNA methylation by tobacco-specific N-nitrosamines. 408 24

1. The absorption, without change, of [(131)I] and [(125)I]solutes of high molecular weight after duodenal infusion has been measured in anaesthetized calves less than 20 hr old by analysis of lymph collected from the thoracic or intestinal duct.2. Factors present in boiled bovine colostrum whey known to be necessary for the rapid absorption of [(131)I]bovine serum gamma-globulin have now been shown to accelerate the passage of [(131)I]polyvinyl pyrrolidone (PVP) of mean mol. wt. 160,000 (K.60) into the lymph in a comparable manner.3. [(131)I]PVP K.30 (mean mol. wt. 40,000) and [(131)I]human serum albumin could be absorbed to some degree in the absence of solvent factors necessary for the absorption of solutes of higher mol. wt. and a large proportion of the solute thus absorbed passed directly into the portal capillaries.4. Lactate and pyruvate and salts of certain lower volatile fatty acids resemble factors in colostrum whey in their facilitation of the absorption of both gamma-globulin and PVP K.60: these active compounds were not however found in colostrum in significant quantities.5. Potassium isobutyrate was the most effective of the compounds tested and at concentrations of 56.7 m-mole/l. generally accelerated absorption to a greater degree than did colostrum whey itself.6. Absorption of both gamma-globulin and PVP K.60 from colostrum whey was characterized by a profuse flow of lymph containing relatively low concentrations of labelled solute. In contrast, when these solutes were fed in solutions containing simple compounds such as potassium isobutyrate they appeared in very high concentrations in the lymph, the flow of which remained relatively scant.7. When [(125)I]PVP was administered in water, little was absorbed. If, however, such an infusion was followed 3 hr later by a duodenal infusion of colostrum, [(125)I]PVP passed into the lymph almost immediately. This response was too rapid for the colostrum to have reached the absorbing cells in the terminal ileum.8. Intravenous infusions of L+lactate have been found to facilitate the absorption of [(125)I]PVP K.60 introduced into the duodenum in water. This indicates that some of the solvent factors which accelerate absorption may reach the terminal ileum via the blood vascular system after they themselves have been absorbed from the upper small intestine.
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PMID:The influence of specific chemical factors in the solvent on the absorption of macromolecular substances from the small intestine of the new-born calf. 418 15

Trent, Dennis W. (University of Oklahoma School of Medicine, Oklahoma City), and L. Vernon Scott. Colorado tick fever virus in cell culture. II. Physical and chemical properties. J. Bacteriol. 91:1282-1288. 1966.-Heat-inactivation kinetics for Colorado tick fever (CTF) virus grown in L cells indicated that more than one rate constant was involved for inactivation at each exposure temperature. An Arrhenius plot of the data indicated the inactivation rate constants to be dependent on the absolute temperature. The energy of activation, for thermal inactivation of the virus, was 17,289 calories per mole, with the Q(10) being 2.6. The optimal pH range for maintenance of CTF viral infectivity was determined to be 7.5 to 7.8. The infectivity of CTF virus was stable to freezing and thawing in diluents which contained: 50% calf serum, 20% glucose, 20% glycerol, 10% bovine serum albumin, 20 mm glutamine, and 2% gelatin. CTF virus replication was insensitive to inhibition by 5-fluoro-2'-deoxyuridine and 5-bromo-2'-deoxyuridine, whereas herpes simplex virus was markedly inhibited, as reported by others. Actinomycin D inhibited CTF virus replication when cells were pretreated for 24 and 12 hr prior to infection, but not when the inhibitor was added at the time of infection. The nucleic acid of CTF virus appears to be of the ribose type.
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PMID:Colorado tick fever virus in cell culture. II. Physical and chemical properties. 428 49


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