Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Suckling rat intestine contains 35 and 65% of the cytosolic and membrane-bound alkaline phosphatase (AP) activities. The corresponding values for sucrase were 20 and 80% respectively. The amount of the soluble enzymes was reduced to 7-11% in adult rat intestine. Administration of cortisone, thyroxine or insulin to suckling animals induced adult type distribution of the enzymes. There were apparent differences in kinetic characteristics of soluble and brush border enzymes, but the kinetic properties of the normally developed and hormone-induced AP and sucrase were essentially similar. This suggested identical nature of these enzymes under these conditions. A biphasic Arrhenius plot was obtained for AP in weaned and hormone injected pups with a break point around 18 degrees C, while the soluble enzyme yielded a monophasic curve (Ea = 8-11 kcal/mole). Arrhenius plot for sucrase was monophasic in the suckling, hormone-injected and adult rat intestine (Ea = 8.3-15.1 kcal/mole). Membrane-bound enzymes were generally labile, while soluble enzyme activities were stable to heat treatment (sucrase at 50 degrees C and AP at 60 degrees C) in various experimental groups.
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PMID:Kinetic characteristics of soluble and brush border alkaline phosphatase and sucrase activities in developing rat intestine: effect of hormones. 235 52

The membrane-bound succinate dehydrogenase (SDH; EC 1.3.99.1) of Bacillus pumilus strain 5 was investigated as succinate:ferricyanide oxidoreductase activity at 27 degrees C. A Km of 8.3 x 10(-3) M was obtained, and the Vmax was 1.8 x 10(-6) mole succinate dehydrogenated min-1 mg-1 membrane protein, at a substrate (succinate) concentration below 40 x 10(-3) M. Above this succinate concentration the Km was 102 x 10(-3) M and the Vmax was 3.7 x 10(-6) mole succinate min-1 mg-1 membrane protein. Para-benzoquinone or 2,4-dinitrophenylhydrazine, in micromolar amounts inhibited the enzyme by serving as an electron sink. Hydroxyl radical (OH.) scavengers, mannitol and benzoate, activated the enzyme, while superoxide dismutase (SOD) had no effect on the enzyme. Thus, the mechanism of electron transfer from succinate to Fe(CN)3-(6) through SDH does not involve superoxide (O2-) as a rate-limiting intermediate.
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PMID:Membrane-bound succinate dehydrogenase of Bacillus pumilus strain 5: effects of modulators of monoelectron transfer. 251 38

3-Hydroxybutyrate dehydrogenase (BDH) is a lecithin-requiring mitochondrial enzyme which catalyzes the interconversion of 3-hydroxybutyrate and acetoacetate with NAD(H) as coenzyme. The purified enzyme devoid of lipid (i.e., the apodehydrogenase or apoBDH) can be reactivated with soluble lecithin or by insertion into phospholipid vesicles containing lecithin. Two different models have been proposed to explain the sigmoidal lipid activation curves. For both models, activation of BDH is assumed to require the binding of two lecithin molecules per functional unit. Activation of soluble enzyme (dimeric form) by short-chain (soluble) lecithin is consistent with a model in which lecithin binding is noncooperative, whereas activation of the membrane-bound enzyme (tetrameric form) indicates cooperativity between the lecithin binding sites. A new comprehensive model is presented in which lecithin is considered to be an essential allosteric activator that shifts the equilibrium between conformational states of the enzyme. Resonance energy transfer data, reflecting NADH binding to membrane-bound and soluble apoBDH, are consistent with such a lecithin-induced conformational change. Apparent dissociation constants for binding of NADH to BDH are approximately 10 microM and approximately 37 microM for BDH activated by bilayer and soluble lecithin, respectively. The maximal fluorescence resonance energy transfer (delta F max) increases with higher mole fraction of lecithin in the bilayer. The largest changes occur between mole fractions 0 and 0.13, thereby correlating with enzymic function. Essentially no binding of NADH is observed in the absence of lecithin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cooperativity in lipid activation of 3-hydroxybutyrate dehydrogenase: role of lecithin as an essential allosteric activator. 274 24

The reactivity of 12 surgically removed uveal melanoma lesions with monoclonal antibodies (MoAb) to 14 membrane-bound and 2 cytoplasmic cutaneous melanoma-associated antigens (MAA), to the 2 subunits of HLA Class I antigens and to the gene products of the HLA-D region was compared with that of cutaneous melanoma lesions and correlated with their histiotype. The membrane-bound determinants defined by the anti-Mr 92,000 and 45,000 MAA MoAb TP39.1, anti-Mr 110,000 MAA MoAb M111, anti-Mr 118,000 MAA MoAb TP36.1, anti-Mr 115,000 MAA MoAb 345.134, anti-ICAM-1 MoAb CL203.4 and anti-Mr 31,000 MAA MoAb M2590, and the cytoplasmic determinants defined by the anti-MAA MoAb 465.12 and 2G-10 display a distribution in uveal melanoma lesions similar to that in cutaneous melanoma lesions. On the other hand, membrane-bound determinants defined by the anti-Mr 100,000 MAA MoAb 376.96, anti-9-O-acetyl-GD3 ganglioside MoAb ME311 and anti-GD2-GD3 ganglioside MoAb ME361 were not detected in the uveal melanoma lesions tested. Furthermore, the membrane-bound determinants defined by the anti-GD3 MoAb R24, anti-nerve growth factor receptor MoAb ME20.4, anti-Mr 97,000 MAA MoAb 140.240, anti-carcinoembryonic antigen MoAb B1.1 and anti-HMW-MAA 149.53, 225.28, and 763.74 have a markedly lower expression in uveal than in cutaneous melanoma lesions. Incubation of uveal melanoma lesions with the pool of the MoAb 149.53, 225.28, and 763.74 recognizing distinct and spatially distant determinants of the HMW-MAA increased the intensity of staining of six lesions and stained four lesions which were not stained by the individual monoclonal antibodies. The distribution of HLA Class I antigens in uveal melanoma lesions resembles that in cutaneous melanoma lesions, since they are expressed in all the lesions of the mixed and epithelioid type but were not detected in those of the spindle type, i.e., the counterparts of nevocellular nevi. HLA Class II antigens are expressed with a lower frequency in uveal than in cutaneous melanoma lesions, since they were detected only in 2 of the 12 lesions. One of them is of the mixed type and the other one of the epithelioid type. Besides HLA antigens the determinants defined by the anti-carcinoembryonic MoAb B1.1, anti-ICAM-1 MoAb CL203.4, and anti-GD3 MoAb R24 displayed a differential distribution in the different histiotypes of uveal melanoma, since they are preferentially expressed in lesions of the mixed and epithelioid type.
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PMID:Analysis of the antigenic profile of uveal melanoma lesions with anti-cutaneous melanoma-associated antigen and anti-HLA monoclonal antibodies. 291 56

Occlusion of Rb+ by C12E8-solubilized (Na+ + K+)-ATPase from shark salt glands has been measured. The rate of de-occlusion at room temperature is about 1 s-1, which is the same as for the membrane-bound enzyme. The amount of Rb+ occluded is 3 moles Rb+ per mole membrane-bound shark enzyme, whereas only about 2 moles Rb+ are occluded by the C12E8-solubilized enzyme.
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PMID:Occlusion of Rb+ by detergent-solubilized (Na+ + K+)-ATPase from shark salt glands. 298 93

Polyneuropathy in Tangier disease can be divided into three clinical types. The most severe form (type III) with a syringomyelia-like syndrome has been described in three cases only. Here, a fourth case of this type is presented. Because of unusual trophic disturbances even leprosy was suspected. Electrodiagnostic findings, including evoked cerebral potentials in this case, were suggestive of a generalized neuropathy with some degree of primary or secondary demyelination and implied possible impairment of central structures. Sural nerve biopsy, including electron microscopy and quantitative analysis, revealed a predominant reduction of smaller myelinated and unmyelinated fibres. The main morphological feature was the abundance of abnormal non-membrane-bound vacuoles in Schwann cells, mostly of the unmyelinated type, and in some endoneurial fibroblasts, macrophages and perineurial cells. There was no inverse relationship between lipid vacuoles and axons in Schwann cell complexes as suspected by others. An excess of endoneurial collagen as well as an increased fascicular area were obvious. In five skin biopsy specimens of different regions typical vacuoles were noted in Schwann cells, histiocytes, nevus cells, and rarely in perineurial cells.
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PMID:Severe polyneuropathy in Tangier disease mimicking syringomyelia or leprosy. Clinical, biochemical, electrophysiological, and morphological evaluation, including electron microscopy of nerve, muscle, and skin biopsies. 299 5

Efficient delivery of hydrophobic water-insoluble substrates and cofactors to membrane-bound enzymes is a recurring problem which has impeded kinetic analyses. Kinetic analysis of the Escherichia coli sn-1,2-diacylglycerol kinase, an extremely hydrophobic integral membrane protein of 122 residues, was facilitated by the development of a mixed micellar assay. beta-Octyl glucoside micelles quantitatively solubilized diacylglycerol kinase from membranes of strains which overproduced the enzyme up to 250-fold and provided an effective method to disperse and deliver the hydrophobic water-insoluble substrate, sn-1,2-dioleoyglycerol. Diacylglycerol kinase was active in mixed micelles containing octyl glucoside and dioleoyglycerol. Several phospholipids stimulated activity up to 6-fold, suggesting a cofactor function. Activation by phospholipids was not stereospecific and was mimicked partially by fatty acids. Half-maximal activation was observed at 1 mol % cardiolipin, suggesting that a small number of phospholipids are sufficient to activate the enzyme. Activity was dependent on the mole fractions of dioleoylglycerol and phospholipid in the mixed micelles, but independent of micelle number. Several lines of evidence indicated that the transfer of diacylglycerol between micelles was much more rapid than its utilization by the enzyme. Diacylglycerol kinase exhibited Michaelis-Menten kinetics with respect to diacylglycerol and MgATP. A second Mg2+ ion (in addition to MgATP) was required for activity. When Mg2+ was excluded from the assay, Mn2+, Zn2+, Cd2+, and Co2+ supported activity to lesser extents. These data establish a suitable system for in-depth kinetic analysis of the E. coli diacylglycerol kinase and its phospholipid cofactor requirements.
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PMID:sn-1,2-Diacylglycerol kinase of Escherichia coli. Mixed micellar analysis of the phospholipid cofactor requirement and divalent cation dependence. 300 49

Liposome prepared from 7:2:1 molar mixtures of phosphatidylcholine, dicetyl phosphate, and cholesterol to which 1-20 mole % dioleoylphosphatidic acid (DOPA) was added were used to examine the effect of membrane-bound monoester phosphatidate anions on calcium phosphate formation in aqueous solutions at 22 degrees C, pH 7.4 and 240 mOsm. Results showed that up to 20 mole % DOPA in the liposomal envelope did not initiate mineralization in solutions made metastable with 2.25 mM CaCl2 and 1.50 mM KH2PO4. Results alos revealed that precipitation induced in metastable solutions by the seeding action of intraliposomally formed mineral was measurably reduced with as little as 1 mole % DOPA and completely suppressed with 5 mole % DOPA. In contrast, 10 mole % concentrations of diester phosphate lipids either had no effect on extraliposomal precipitation (e.g., phosphatidylglycerol and phosphatidylinositol) or, as reported previously for phosphatidylserine) only partially reduced the amount of precipitate formed. Transmission electron microscopical analysis suggests that DOPA-containing lipid bilayers adhering to the seed crystals inhibited extraliposomal mineralization by encapsulating the crystals within the liposomes and/or by blocking potential growth sites on the crystal faces. The polar head group of DOPA, being more negatively charged and sterically less encumbered than diester phosphate ligands, most probably was responsible for this adherence of the lipid bilayers to the crystal surfaces.
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PMID:Modulation of calcium phosphate formation by phosphatidate-containing anionic liposomes. 314 28

Supported phospholipid bilayers prepared by Langmuir-Blodgett techniques were introduced recently as a new model membrane system [Tamm, L.K., & McConnell, H.M. (1985) Biophys. J. 47, 105-113]. Here, supported bilayers are applied to study the lateral diffusion and lateral distribution of membrane-bound monoclonal antibodies. A monoclonal anti-trinitrophenol antibody was found to bind strongly and with high specificity to supported phospholipid bilayers containing the lipid hapten (trinitrophenyl)phosphatidylethanolamine at various mole fractions. The lateral distribution of the membrane-bound antibodies was studied by epifluorescence microscopy. The bound antibodies aggregated into patches on a host lipid bilayer of dimyristoylphosphatidylcholine below the lipid chain melting phase transition and redistributed uniformly on fluid-phase supported bilayers. Lateral diffusion coefficients and mobile fractions of fluorescent phospholipid analogues and fluorescein-labeled antibodies were measured by fluorescence recovery after pattern photobleaching. The lateral diffusion coefficients of the membrane-bound antibodies resembled those of the phospholipids but were reduced by a factor of 2 in the fluid phase. The lipid chain melting phase transition was also reflected in the lateral diffusion coefficient of the bound antibody but occurred at a temperature about 3 deg higher than the phase transition in supported bilayers of pure phospholipids. The antibody lateral diffusion coefficients decreased in titration experiments monotonically with increasing antibody surface concentrations by a factor of 2-3. Correspondingly, a relatively small decrease of the antibody lateral diffusion coefficient was observed with increasing mole fractions of lipid haptens in the supported bilayer.
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PMID:Lateral diffusion and fluorescence microscope studies on a monoclonal antibody specifically bound to supported phospholipid bilayers. 336

A new membrane-bound b-type cytochrome, cytochrome b-558, was removed from chromatophore membranes of photosynthetically grown Rhodopseudomonas sphaeroides strain R-26 by deoxycholate-cholate extraction. The cytochrome was purified by ammonium sulfate fractionation and ion-exchange chromatography. Cytochrome b-558 had absorption maxima at 280 and 405 nm in the oxidized form, and at 558, 528, and 420 nm in the reduced form. It had a midpoint potential of--130 mV at pH 7.0. The minimal molecular weight of this protein was 42,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it contained one mole heme per mole of protein. The isoelectric point was 8.5. The electrophoretic pattern of heme-carrying proteins and the redox potentiometry showed that cytochrome b-558 was present in membranes from wild type, strain R-26, and strain GA grown photosynthetically, but not from any strain grown aerobically.
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PMID:A new membrane-bound b-type cytochrome, cytochrome b-558, from photosynthetically grown Rhodopseudomonas sphaeroides. 348 57


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