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:C0026918 (Mycobacterium)
52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binding studies of various nucleotides to the purified coupling factor-latent ATPase from Mycobacterium phlei have been carried out using gel filtration, equilibrium dialysis, and ultrafiltration methods. The purified latent ATPase binds 3 mol of ADP per mol of the enzyme with an apparent dissociation constant of 68 muM. Binding of nucleotides occurred in the decreasing order: ADP, epsilon-ATP, epsilon-ADP, UDP, adenyl-5'-yl imidodiphosphate (AMP-P(NH)P), IDP, and adenosine 5'-(alpha,beta-methylene)diphosphate (AdoP(CH2)P). AMP-P(NH)P inhibits both soluble (Ki = 77 muM) and membrane-bound latent ATPase activity. However, AMP-P(NH)P does not affect oxidative phosphorylation in membrane vesicles of M. phlei. AMP-P(NH)P exhibits one binding site per molecule of the enzyme with a dissociation constant of 71 muM. After trypsin treatment of the enzyme, the binding of ADP decreases 35%, while AMP-P(NH)P binding remains unchanged. Moreover, AMP-P(NH)P binding was not displaced by ADP. Studies with sulfhydryl agents showed that, in contrast to AMP-P(NH)P, binding of at least 1 mol of ADP requires the participation of sulfhydryl groups. The results indicate that AMP-P(NH)P and ADP do not share a common binding site and that the latent ATPase enzyme has separate sites for ATP hydrolysis and ATP synthesis.
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PMID:Binding of nucleotides to purified coupling factor-latent ATPase from Mycobacterium phlei. 1 31

Active transport of proline remained unaffected in phospholipase A-treated electron transport particles from Mycobacterium phlei. However, the steady state level of proline was reduced 50 to 60% in phospholipase A-treated depleted electron transport particles that were devoid of membrane-bound coupling factor-latent ATPase activity. The decrease in the uptake of proline in the phospholipase A-treated depleted electron transport particles was not due to a change in the apparent K-m for proline, but it was related to the amount of phospholipid cleaved from the membranes. Restoration in the level of proline transport in phospholipase A-treated depleted electron transport particles was achieved by reconstituting these vesicles with diphosphatidylglycerol and phosphatidylethanolamine liposomes. Diphosphatidylglycerol was found to be most effective in the restoration of proline uptake. In contrast to the effect of phospholipase A treatment on proline transport, similar treatement of the electron transport particles or depleted electron transport particles failed to inhibit the active transport of either glutamine or glutamic acid. Studies with phospholipase A-treated membrane vesicles confirmed earlier findings that a proton gradient is not required for active transport of amino acids.
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PMID:Effect of phospholipase A on active transport of amino acids with membrane vesicles of Mycobacterium phlei. 12 19

The membrane-bound coupling factor from Mycobacterium phlei was solubilized from membrane vesicles by washing with low ionic strength buffer or 0.25 M sucrose. The solubilized enzyme exhibited coupling factor, latent ATPase, and succinate oxidation-stimulating activity. Purification by affinity chromatography using Sepharose coupled to ADP yielded a homogeneous preparation of latent ATPase which was purified about 200-fold with an 84% yield in a single step. Purified latent ATPase exhibited coupling factor activity but no succinate oxidation-stimulating activity. The molecular weight of latent ATPase was determined to be 250,000 +/- 10,000 by Sephadex G-200 chromatography. The ATPase was unmasked by trypsin treatment and activated by Mg2+ ion. However, trypsin treatment inactivated the coupling factor activity in the purified enzyme, indicating that the catalytic sites for ATPase and coupling activity are different. Unlike mitochondrial ATPase, latent ATPase from M. phlei was not cold-labile. Of the nucleoside triphosphates, UTP, ITP, and epsilon-ATP (1-N6-ethenoadenosine triphosphate) were hydrolyzed to a lesser extent compared to ATP. Kinetic data showed that ADP acted as a competitive inhibitor of latent ATPase activity with a Ki of 5 x 10(-3) M. Uncouplers of oxidative phosphorylation and respiratory inhibitors did not affect the latent ATPase activity, while sodium azide (0.1 mM) inhibited the latent ATPase activity.
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PMID:Energy-transducing membrane-bound coupling factor-ATPase from Mycobacterium phlei. I. Purification, homogeneity, and properties. 12 54

The membrane bound coupling factor-latent ATPase was solubilized from the membrane vesicles of Mycobacterium phlei by using 0.25 M sucrose or low ionic strength buffer. Purification of the solubilized enzyme by use of Sepharose-ADP conjugate gel yielded a homogenous preparation of latent ATPase which was purified about 216-fold in a single step with an 84% yield. The enzyme exhibits a specific activity of 39 mumoles of ATP hydrolyzed per min per mg protein. The purified enzyme exhibits coupling factor activity. Electrophoresis in two dissociating solvent systems indicates that the enzyme contains at least three major polypeptides of molecular weights 56,000, 51,000, and 46,000 daltons, and two minor polypeptides of 30,000 and 17,000 daltons. Equilibrium binding studies of ADP with purified coupling factor-latent ATPase reveal the presence of two nucleotide binding sites per molecule with an apparent Ka of 8.1 X 10(-5) M. By use of affinity chromatography, another latent ATPase has been isolated from the solubilized enzyme, which does not exhibit coupling factor activity.
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PMID:Purification and properties of membrane-bound coupling factor-latent ATPase from Mycobacterium phlei. 12 86

Latent ATPase, located on the inner surface of protoplast ghosts of Mycobacterium phlei, was unmasked either by trypsin or an impermeable form of trypsin, ethylene maleic anhydride-trypsin. Density gradient experiments showed that the ghost preparations remained intact following trypsin treatment. Evidence was obtained that 125I-trypsin failed to penetrate the ghost membranes. Thus, attempts were made to determine whether the ATPase molecule in the ghost membranes is accessible from the outer surface. Treatment of protoplast ghosts and trypsin-treated ghosts with 125I by the lactoperoxidase method resulted in the labeling of ATPase only in the trypsin-treated ghost preparations. The antibody to latent ATPase inhibited ATPase activity in trypsin-treated ghosts. The changes in the fluorescence polarization of diphenyl hexatriene indicated that trypsin treatment of the ghost membranes resulted in an increase in membrane fluidity. These studies suggest that the latent ATPase moiety has undergone translocation to the outer surface or it became accessible to trypsin digestion from the outer surface of the membranes as a result of removal of some proteins covering ATPase molecule in the membranes.
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PMID:Trypsin-induced changes in the orientation of latent ATPase in protoplast ghosts from Mycobacterium phlei. 14 35

The energy-transducing N,N'-dicyclohexylcarbodiimide-sensitive (DCCD-sensitive) ATPase complex consists of two parts, a soluble catalytic protein (F1), and an intrinsic membrane protein (F0). The bacterial coupling factor complex, BCF0-BCF1, has recently been purified from Mycobacterium phlei, and used to reconstitute oxidative phosphorylation in detergent-extracted membranes. The BCF0 moiety has been purified by being recovered from the purified BCF0-BCF1 complex by affinity chromatography. BCF0 is a lipoprotein or lipoprotein complex with an approximate molecular weight of 60,000. The preparation contained 0.15 mg of phospholipid per milligram protein. There appear to be three polypeptides, with approximate molecular weights of 24,000, 18,000, and 8,000 as determined by sodium dodecylsulfate acrylamide gel electrophoresis. Purified BCF0 conferred DCCD sensitivity on a purified BCF1 preparation. Reconstitution of oxidative phosphorylation was achieved after incubation of detergent-extracted membranes with purified BCF0 and purified BCF1.
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PMID:Purification and characteristics of hydrophobic membrane protein(s) required for DCCD sensitivity of ATPase in Mycobacterium phlei. 15 36

Trypsin treatment of solubilized coupling factor-latent ATPase from Mycobacterium phlei alters its subunit structure and functional properties. This coupling factor exhibits ATPase activity following trypsin treatment. Concurrently, both the ability of the enzyme to rebind to membranes depleted of coupling factor and its capacity for coupled phosphorylation are lost. The native alpha (64 000 dalton) subunit undergoes limited proteolytic digestion, and the delta (14 000 dalton) subunit is partially lost. During the course of tryptic proteolysis, the coupling factor molecule may exist in one of ten unique structural state (e.g. the native, ATPase-inactive molecule exists in the alpha alpha alpha state). Rigorous analysis of the experimental data by theoretical modeling provided information concerning the intermediate structural states leading to the fully ATPase-activated alpha" alpha" alpha" state under different conditions of trypsin treatment. The theoretical models of structure-function relationships that best-represented the experimental data predicted that the native coupling factor molecule contains three copies of the alpha (64 000 dalton) form of the alpha subunit, that the alpha" (58 000 dalton) alpha subunit species contributes maximally and the alpha' (61 000 dalton) form about half-maximally to ATPase activity, that membrane rebinding ability is proportional to the number of native alpha subunits in the enzyme, and that at least one native alpha subunit/molecule is required for full expression of coupled phosphorylation. These results indicate an essential role for the alpha subunit in the regulation of ATPase activity and in the ability of the solubilized coupling factor to rebind to depleted membranes.
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PMID:Tryptic proteolysis of coupling factor-latent ATPase from mycobacterium phlei. Theoretical modeling of structure-function relationships. 15 57

The activation of the coupling factor-latent ATPase enzyme by tryptic proteolysis may resemble the activation of many proenzymes by limited proteolysis. The beta (53 000 dalton) subunit of solubilized coupling factor-latent ATPase from Mycobacterium phlei was selectively lost in some trypsin-treated samples. Since a concomitant loss of ATPase activity was not observed, the beta subunit may not be essential for ATPase catalytic activity. Treatment of solubilized coupling factor with chymotrypsin rapidly produced an A'-type (61 000 dalton) species from the native alpha (64 000 dalton) subunits with partial activation of the APTase enzyme. Secondary chymotryptic cleavage yielded an A"-type (58 000 dalton) species and a less-active enzyme. Storage of fresh coupling factor samples at -20degreeC in the presence of 4 mM MgCl2 with several freeze-thaw cycles resulted in loss of ATPase activity without apparent change in alpha subunit structure. Storage at 4 degrees C in the presence or absence of MgCl2 both decreased ATPase activity and generated A'-type alpha subunit species. Since presence was suspected. The peptide bonds first cleaved by trypsin, chymotrypsin, and the unknown protease are all apparantly located within the same small segment of alpha subunit polypeptide chain.
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PMID:Limited proteolysis of coupling factor-latent ATPase from Mycobacterium phlei. Effects of different enzymes and modifying agents. 15 59

Active transport of calcium ions has been demonstrated in inside-out membrane vesicles from Mycobacterium phlei mediated by respiratory linked substrates as well as by ATP hydrolysis. The uptake of calcium exhibited an apparent Km of 80 microM and V of 16.6 nmol calcium uptake x min-1 x mg protein-1. A fortyfold concentration gradient for calcium ions was calculated for both the ATP-induced and the respiration-induced transport of calcium. Removal of coupling-factor-latent ATPase resulted in the complete loss of ATP-driven Ca2+ transport whereas the respiration-driven uptake was reduced by 40-50%. The uptake of calcium was inhibited by the proton conducting ionophores carbonylcyanide m-chlorophenylhydrazone and Gramicidin-D. The accumulated calcium was freely exchangeable with external calcium and was rapidly released by the addition of inhibitors of energy transduction, proton-translocating uncouplers or the ionophore A23187. The uptake of the weak base, methylamine, upon the oxidation of respiratory-linked substrates or the hydrolysis of ATP showed the generation of a protein gradient (inside acidic) which was partially collapsed on the addition of calcium ions. These results suggest that a Ca2+/H+ antiport mechanism may be responsible for the transport of calcium.
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PMID:Active transport of calcium in membrane vesicles from Mycobacterium phlei. 15 18

The phospholipid composition of the electron transport particles and coupling factor-depleted electron transport particles of Mycobacterium phlei are the same, but they differ in contents. The accessibility of partially purified phospholipase A to these membrane phospholipids was found to be different. Treatment of membranes of Mycobacterium phlei with phospholipase A impairs the rate of oxidation as well as phosphorylation. The inhibition of phosphorylation can be reversed by washing the membranes with defatted bovine serum albumin. The reconstitution of membrane-bound coupling factor-latent ATPase activity to phospholipase A-treated depleted electron transport particles and their capacity to couple phosphorylation to oxidation of substrates remained unaffected after phospholipase A treatment. However, the pH gradient as measured by bromthymol blue was not restored after reconstitution of phospholipase A-treated depleted electron transport particles with membrane-bound coupling factor-latent ATPase. These findings show that the phosphorylation coupled to the oxidation of substrates can take place without a pronounced pH gradient in these membrane vesicles. The dye 1-anilino-8-naphthalene sulfonic acid (ANS) exhibited low levels of energized and nonenergized fluorescence in phospholipase A-treated membranes. This decrease in the level of ANS fluorescence in phospholipase A-treated membranes was found to be directly related to the amount of phospholipids cleaved. The decrease in the energy-dependent ANS response in phospholipase A-treated electron transport particles, as compared with untreated electron transport particles, was shown to be a result of a change in the apparent K-d of the dye-membrane complex, and of a decrease in the number of irreversible or slowly reversible binding sites, with no change in the relative quantum efficiency of the dye. The decrease in ANS fluorescence in phospholipase A-treated particles appears to be due to a decrease in the hydrophobicity of the membranes.
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PMID:Effect of phospholipase A on the structure and functions of membrane vesicles from Mycobacterium phlei. 23 99


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