Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The D-aminoacylase produced by Alcaligenes denitrificans DA181 was a new type of aminoacylase which had both high stereospecificity and specific activity. The molecular weight and isoelectric point of this enzyme were 58,000 and 4.4, respectively. The apparent Km and kcat values of this enzyme for N-acetyl-D-methionine were estimated to be 0.48 mM and 6.24 x 10(4) min-1, respectively. The optimum temperature was 45 degrees C. The enzyme was stable up to 55 degrees C for 1 hr in the presence of 0.2 mg/ml bovine serum albumin. The enzyme was stable in the pH range of 6.0 to 11.0 with an optimum pH of 7.5. This enzyme contained about 2.1 g atom of zinc per mole of enzyme. Enzyme activity was inhibited by incubation with EDTA. The inhibition by EDTA was fully reversed by Co2+ and partially by Zn2+.
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PMID:Characterization of D-aminoacylase from Alcaligenes denitrificans DA181. 136 43

Sera from 17 patients with Type I diabetes and 19 healthy volunteers have been examined to evaluate whether the kinetics of the binding of drugs to Site II of serum albumin is altered in diabetes. Stopped-flow measurements showed that the association velocity and the affinity constants of the fluorescent marker dansylsarcosine were significantly lower in diabetes (160 s-1 and 2.0 x 10(5) l.mol-1) than in non-diabetics (196 s-1 and 4.0 x 10(5) l.mol-1). The dissociation velocity was not different [20.3 s-1 vs. 19.4 s-1]. Although patients with a reduced albumin concentration were excluded the diabetics had significantly lower concentrations than the healthy volunteers. There was a significant correlation between decreased glycosylation of albumin and increased association velocity. The dissociation velocity constants were correlated with the molar concentration ratio of free fatty acids/human serum albumin. Thus, the extent of glycosylation and the amount of fatty acids bound per mole albumin can both affect the kinetics of drug binding to Site II. The lower affinity in patients with Type I diabetes is due to the increased in the glycoalbumin concentration.
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PMID:Drug-protein binding kinetics in patients with type I diabetes. 138 Apr 61

A simple and sensitive enzymatic method for determination of plasma and serum fatty acids (FAs) is described. The method is based on acylation of long chain FAs by a bacterial acyl-CoA synthetase (ACS) producing equivalent amounts of acyl-CoA and AMP. AMP production was measured using the coupled reaction of myokinase (MK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) allowing fluorinate detection of NADH. Two moles of NAD were produced per mole of FA acylated. Concentrations of substrates and enzymes were kept as low as possible maintaining the ACS reaction as rate limiting. Addition of fat-free human serum albumin (HSA) to standards reduced initial reaction rates but did not affect end-point fluorescence levels. Triton X-100 partly counteracted the inhibition by HSA. To keep albumin concentration low, plasma or serum samples were diluted by 1:400. Duplicate measurements of plasma or serum FA concentrations between 0 and 2 mmol l-1 can then be performed on 5 microliters samples with intra- and inter-assay variation coefficients of 1.7 and 4% respectively.
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PMID:Enzymatic microdetermination of plasma and serum free fatty acids. 145 65

Alpha-crystallin exhibits variable inhibition of several members of the chymotrypsin family of proteinases. Complete inhibition of elastase was obtained by the addition of either alpha-crystallin or a sonicated preparation of the water-insoluble fraction from bovine lens. Little or no inhibition was seen, however, with either beta-crystallin or bovine serum albumin under the same conditions. Complete binding of elastase was demonstrated by Sephadex G-100 gel filtration chromatography, and a direct correlation between binding and inhibition was obtained. This observation permitted us to do a Scatchard analysis of the inhibition data. Scatchard plots for the binding of elastase gave a biphasic response suggesting two separate binding sites. These sites had Kd values of 15 and 40 nM for alpha-crystallin and 6 and 42 nM for the bovine water-insoluble fraction. Similarly, a Dixon plot exhibited a Ki value of 3 nM and was consistent with non-competitive inhibition. One mole of alpha-crystallin (8 x 10(5) Da), or an equivalent amount of water-insoluble protein, bound from 13 to 19 mol of elastase which were about equally divided between the higher and lower affinity sites. Saturation studies confirmed 20 and 16 elastase binding sites per 8 x 10(5) Da for alpha-crystallin and water-insoluble protein, respectively. DFP-elastase was capable of binding to alpha-crystallin suggesting that a proteolytic cleavage was not required for complex formation. Stability measurements showed a linear return to 60% of the original activity over a 30-min period. Therefore, the interaction between elastase and alpha-crystallin resembles that of a heterologous protease:inhibitor complex in both binding and stability.
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PMID:Characterization of the elastase inhibitor properties of alpha-crystallin and the water-insoluble fraction from bovine lens. 154 28

The kinetics of hydrolysis of 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine vesicles catalyzed by the high molecular weight phospholipase A2 from rat kidney show an anomalous behavior. The reaction progress lasts for several minutes and then stops after only 5-10% of the available substrate has been hydrolyzed. Addition of more enzyme but not more substrate leads to a new round of hydrolysis. Although this initially suggested that the enzyme becomes inactivated during the turnover, such a conclusion could not be substantiated. Addition of buffer containing 0.15 M NaCl and bovine serum albumin to the reaction after the progress ceased leads to the re-initiation of the lipolysis. The enzyme is not strongly inhibited by the reaction products. Although the enzyme does not bind irreversibly to vesicles composed of pure 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine, it does become irreversibly trapped on vesicles that contain a critical mole percentage of reaction products. This trapping is the most likely explanation for the cessation of the reaction progress. Both the binding of enzyme to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine vesicles and the hydrolysis of 1-stearoyl-2-[3H]arachidonyl-sn-glycerophosphocholine contained in these vesicles require the presence of products. Furthermore, the trapping of enzyme is independent of catalytic turnover. The trapping is sensitive to the structure of the fatty acid present in the vesicles and requires the presence of divalent metals (either Ca2+, Sr2+, Ba2+, or Mg2+). Since the concentrations of the metals needed for the enzymatic activity correlate with the amounts needed to promote the trapping, it is suggested that the role of the metal is only to promote the interfacial binding of the enzyme.
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PMID:Kinetic analysis of a high molecular weight phospholipase A2 from rat kidney: divalent metal-dependent trapping of enzyme on product-containing vesicles. 156 37

The binding of Cd(II) and Zn(II) to human serum albumin (HSA) and dog serum albumin (DSA) has been studied by equilibrium dialysis and 113Cd(II)-NMR techniques at physiological pH. Scatchard analysis of the equilibrium dialysis data indicate the presence of at least two classes of binding sites for Cd(II) and Zn(II). On analysis of the high-affinity class of sites, HSA is shown to bind 2.08 +/- 0.09 (log K = 5.3 +/- 0.6) and 1.07 +/- 0.12 (log K = 6.4 +/- 0.8) moles of Cd(II) and Zn(II) per mole of protein, respectively. DSA bound 2.02 +/- 0.19 (log K = 5.1 +/- 0.8), and 1.06 +/- 0.15 (log K = 6.0 +/- 0.2) moles of Cd(II) and Zn(II) per mole of protein, respectively. Competition studies indicate the presence of one high-affinity Cd(II) site on both HSA and DSA that is not affected by Zn(II) or Cu(II), and one high-affinity Zn(II) site on both HSA and DSA that is not affected by Cd(II) or Cu(II). 113Cadmium-HSA spectra display three resonances corresponding to three different sites of complexation. In site I, Cd(II) is most probably coordinated to two or three histidyl residues, site II to one histidyl residue and three oxygen ligands (carboxylate), while for the most upfield site III, four oxygens are likely to be involved in the binding of the metal ion. The 113Cd(II)-DSA spectra display only two resonances corresponding to two different sites of complexation. The environment around Cd(II) at sites I and II on DSA is similar to sites I and II, respectively, on HSA. No additional resonances are observed in any of these experiments and in particular in the low field region where sulfur coordination occurs. Overall, our results are consistent with the proposal that the physiologically important high-affinity Zn(II) and Cd(II) binding sites of albumins are located not at the Cu(II)-specific NH2-terminal site, but at internal sites, involving mostly nitrogen and oxygen ligands and no sulphur ligand.
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PMID:Binding of cadmium(II) and zinc(II) to human and dog serum albumins. An equilibrium dialysis and 113Cd-NMR study. 181 86

A monoclonal antibody reacting with progesterone has been raised by fusion of mouse myeloma cells (SP20) and splenocytes of BALB/c mice hyperimmunized with 4-pregnane 3,20 dione conjugated to bovine serum albumin. Association constant of this antibody for binding with progesterone was 0.22 x 10(9) l/mole. The antibody was highly specific for progesterone. A single ip injection of this antibody brought about an antifertility effect which is influenced by genotype. Antibody treatment brought about a significant decrease in the fetal weight and a slight decrease in the plasma progesterone levels. The antifertility effect could be reversed only up to day 3 by exogenous administration of progesterone.
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PMID:Production and characterisation of a monoclonal antibody to progesterone and its effect on fertility. 186 23

Extent of adsorption (gamma pw) of bovine serum albumin, beta-lactoglobulin, gelatin and myosin at the alumina-water interface has been measured as function of protein concentration (Cp) at several temperatures, pH, and ionic strengths of the medium. gamma pw for proteins in most cases increases with increase of protein concentration but it attains maximum value gamma pw(m) when Cp is high. Values of maximum adsorption have been examined in terms of molecular orientation, molecular size and shape and unfolding of the packed proteins at the interface. In few cases, gamma pw increases with increase of Cp without reaching a real state of saturation as a result of aggregation of molecules or extensive unfolding of the protein at the interface. In the case of beta-lactoglobulin at pH 5.2 and ionic strength 0.05, gamma pw in high concentration region decreases to zero value when Cp increases. For myosin at 45 degrees C and pH 6.4, and also at 27 degrees and pH 7.8, the values of gamma pw are all negative and these negative values increase with increase of Cp. All these results have been explained in terms of significant competitions of water and protein for binding to the surface sites of the powdered alumina. Adsorption of myosin has also been found to be affected in the presence of NaCl, KCl, CaCl2, KI, Na2SO4, LiCl and urea. The relative affinities of the adsorption of various proteins for the surface of alumina at different physical conditions of the system have been compared in terms of maximum values of adsorption attained when gamma pw is varied with Cp. The affinities are shown to be compared more precisely in terms of the standard free energy decrease for the saturation of the surface by protein as a result of the change in its concentration from zero to unity in the mole fraction scale.
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PMID:Protein adsorption at solid-liquid interfaces: Part I--Affinities of proteins for alumina surface. 187 68

The products of the reactions of ozone with aqueous emulsions of unsaturated fatty acids and with liposomes made from phosphatidylcholine esters were characterized. Ozonolysis of emulsions of methyl oleate yields approximately 1 mol of hydrogen peroxide and 2 mol of aldehydes per mole of ozone used and fatty acid reacted. That is, the net equation that occurs is RCH = CHR' + O3 + H2O----RCHO + R'CHO + H2O2 . Ozonolysis of emulsions of oleic, linoleic, linolenic, and arachidonic acids gives 1 mol of hydrogen peroxide per mole of ozone used. Only very low yields (less than 5%) of reducible materials other than hydrogen peroxide are observed, suggesting that the yields of organic peroxidic materials, including Criegee ozonides and lipid hydroperoxides, are small. Ozonolysis of rat erythrocyte ghost membranes and rat bronchoalveolar lavage also gives significant yields (about 50%) of hydrogen peroxide based on the moles of ozone consumed. Reactions of ozone with bovine serum albumin, glutathione, and glucose do not produce hydrogen peroxide, implying that the hydrogen peroxide formed during the ozonation of biological materials arises almost exclusively from ozone/olefin reactions. Hydrogen peroxide and aldehydes are suggested to be important mediators of the modifications observed in both the lung and extrapulmonary tissues when ozone is inhaled.
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PMID:The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity. 191 18

A nonperturbing 13C nuclear magnetic resonance (NMR) method was used to monitor the equilibrium distribution of carboxyl 13C-enriched fatty acids (FA) between distinct binding sites on human serum albumin, native human lipoproteins, and/or phospholipid model membranes, under conditions that mimic the normal and diabetic human circulation. Two variables pertinent to the diabetic circulation were examined: FA/albumin mole ratio (as elevated in insulin deficiency and/or nephrosis) and pH (as decreased in acidosis). 13C NMR spectra for samples containing carboxyl 13C-enriched palmitate, human serum albumin, and phospholipid vesicles or native lipoproteins (all samples at pH 7.4, 37 degrees C) exhibited up to six carboxyl NMR resonances corresponding to FA bound to distinct binding sites on albumin and nonalbumin components. When the sample FA/albumin mole ratio was 1, three FA carboxyl resonances were observed (182.2, 181.8, and 181.6 ppm; designated peaks beta, gamma, and beta', respectively). These resonances corresponded to FA bound to three distinct high-affinity binding sites on human serum albumin. When the sample mole ratio value exceeded 1, additional carboxyl resonances corresponding to FA bound to phospholipid vesicles (179.0 ppm, peak phi), lipoproteins (180.7 ppm, peak sigma), and lower affinity sites on albumin (183.8 ppm, peak alpha; 181.9 ppm, peak gamma'), were observed. The intensity of peaks phi and sigma increased with increasing mole ratio or decreasing pH. Using Lorentzian lineshape analysis, the relative mole quantities of FA bound to albumin and nonalbumin binding sites were determined. Plots of the fraction of FA associated with nonalbumin components as a function of FA/albumin mole ratio were linear and extrapolated to the abscissa at a mole ratio value of 1. This pattern of FA distribution was observed regardless of the type of nonalbumin acceptor used (phospholipid vesicles, human high- or low-density lipoproteins) or the type of FA used (palmitate, oleate, or stearate), and provided evidence for negative cooperativity for human serum albumin upon binding of 1 mol of FA per mole albumin. These in vitro NMR results suggest that the threshold FA/albumin mole ratio value for alterations in FA distributions in the human circulation may be 1, rather than 3, as previously held. The pathophysiological implications of these findings are discussed.
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PMID:Fatty acid distribution in systems modeling the normal and diabetic human circulation. A 13C nuclear magnetic resonance study. 201 May 53


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