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Determinazione mediante HPLC dell'acido gentisico nelle urine di soggetti trattati con aspirina
No full textPhospholipid-dependent assembly of mitochondrial ATPase complex.
No full text1. Phosphatidylcholines of different acyl-chain composition and a preparation of ATPase complex depleted of phospholipids have been employed in order to evaluate the contribution of lipid bilayer to the assembly of this multi-subunit component of mitochondrial membrane. 2. At the minimal requirement for bilayer assembly (dinonanoylphosphatidylcholine, mixtures of lysophosphatidylcholine and phosphatidylcholine), fragments with oligomycin-insensitive ATPase activity are reconstituted. Conformational changes with dislocation of ATPase complex subunits may explain these results. 3. At increased strength of acyl-chain interaction (dilauroylphosphatidylcholine and higher homologues), the damage to the ATPase complex is prevented but this is not sufficient to achieve functional restoration. Bilayers with a tendency to coalesce and fuse aggregate in large amounts with the complex and yield low ATPase reactivation. Bilayers of high stability yield complexes with physiological content of phospholipids and efficient ATPase activity. Transition between these two possibilities is found at sixteen carbon acyl-chains. Only at this chain length does the cholate dialysis procedure of reconstitution become feasible. 4. It is concluded that a minimum of 16 carbon atoms in each chain are required to organize a bilayer structurable to maintain the ATPase complex conformation and to sustain the transmembrane position of the whole assembly
Effect of caramellization and Maillard reaction products on peroxidase activity
No full textSolutions of D-fructose and sucrose were heated, alone and in the presence of glycine. The reaction products were examined in terms of their effects on peroxidase (POD) activity. Compared with glucose mixtures, fructose products had a great inhibiting effect on POD activity, while in the case of Maillard reaction products (MRPs), the differences in antibrowning activity between fructose-glycine and glucose-glycine mixtures were slight. Rs regards the sucrose and sucrose-glycine solutions, a slight inhibiting effect on POD activity was observed only after sugar hydrolysis. Measurements of the reducing power of sugar and sugar-amino acid solutions showed a correspondence between antioxidant properties of caramelization and Maillard reaction products and their antibrowning effects
Regulation of phospholipid-ATPase complex interaction by the adenine nucleotide carrier.
No full text1) The effect of phospholipids on a preparation containing the ATPase complex and the adenine nucleotide carrier is studied in the presence of ligands known to affect the conformation of these components of the mitochondrial inner membrane. (2) When ATPase activity is abolished by phospholipid depletion, the reactivation induced by phosphatidylcholine is prevented by the simultaneous addition of ATP. ADP partially reproduces the ATP effect. AMP, GTP, UTP, and Pi are ineffective. (3) The influence of ATP is associated with reduced phospholipid binding to the membrane fragments and is reversible. The ATP effect on reconstitution is not manifest when phosphatidylcholine is added together with negatively charged phospholipids. (4) Carboxyatractyloside does not modify the phospholipid-ATPase complex interaction but bongkrekic acid is as effective as ATP. In the presence of ADP, the influence of bongkrekic acid is considerably increased. (5) It is concluded that the binding of ATP to the adenine nucleotide carrier enables the complex to select between the charged and uncharged phospholipids. As a result of the carrier conformational change, the ATPase complex is induced to prefer a negatively charged phospholipid environment
Attività enzimatiche nei sistemi ad umidità intermedia: 1. influenza dei prodotti della reazione di Maillard (MRP) sull'attività delle polifenolossidasi (PPO)
No full text[Function of phospholipids in a membranous in a membranous complex with ATPase activity].
No full textINHIBITION OF LISTERIA MONOCYTOGENES BY LACTOCOCCUS LACTIS SUBSP. LACTIS ISOLATED FROM ITALIAN RAW HAM
No full textPartial inactivation of microbial proteinases with soybean Kunitz and Bowman-Birk inhibitors
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