1,721,270 research outputs found
Production and characterization of monoclonal antibodies against L-carnitine: Radioimmunologic assays for L-carnitine determination
No full textMonoclonal antibodies against L-carnitine have been produced and characterized, These antibodies have been found to specifically bind L-carnitine and, with different affinities, other carnitine-related compounds. No binding was observed with choline or acetylcholine. These antibodies have been used to measure L-carnitine in biological samples and serum. Data obtained demonstrate that, in biological samples, by using radiolabelled carnitine, it is possible quickly to detect small amounts of carnitine. The high specificity of the test is clearly demonstrated
Temperature modulation of bovine hemoglobins
No full textThe functional properties of hemoglobin from Egyptian water buffalo have been characterized as a function of pH, temperature and chloride concentration. Alongside overall similarities shared with ox and Arctic ruminant hemoglobins, hemoglobin from buffalo shows significant differences with respect to the effect of temperature. The results obtained may suggest that the limited effect of temperature on oxygen binding recently reported for ox hemoglobin could be regarded as an interesting case of a reminiscence of a past glacial age
Could G6PD-Buenos-Aires confirm the existence of the "structural NADP+ binding site" and its strategic role for the stability and/or activity enzyme?
No full textHapten-carrier interactions and their role in the production of monoclonal antibodies against hydrophobic haptens
No full textThe coupling of haptens to carrier proteins is required for the generation of antihapten antibody response, To date, different polypeptides (such as gelatin, albumin, and keyhole limpet hemocyanin) have been used to increase the immune response against haptens, Different methods of conjugation have also been used to increase the specificity of the antibody response, Our results, obtained through an analysis of the antibody response at both the polyclonal and the monoclonal levels, show that carrier proteins specifically modulate the antibody titer, the specificity of the response, the fusion efficiency, and the number of specific clones, Moreover, the affinity constants of both serum and randomly selected hybridomas directed against different haptens have been found to be exclusively modulated by carrier proteins, In addition, the results show that the carrier protein should be selected considering its possible physicochemical interaction with haptens, Data obtained suggested that any carrier is suitable for hydrophilic haptens, while the choice of the carrier for hydrophobic haptens is critical in obtaining a specific immune response, The use of specific carriers allowed the production of highly specific antibodies: even IgMs, obtained by using these carriers, were able to specifically react with hydrophobic haptens; the case of some IgM monoclonal antibodies specifically reacting with protoporphyrin IX is reported
Human hemoglobin cross-linked through the polyphosphate-binding site. Functional properties and evidence for conformers
No full textThe properties of human hemoglobin reacted with 2-nor-2-formylpyridoxal 5'-phosphate, a bifunctional derivative of pyridoxal 5'-phosphate, have been investigated both from an equilibrium and kinetic point of view. The experimental data, interpreted in terms of the two-state allosteric model, indicate that a perturbed R state is characteristic of this modified low ligand affinity hemoglobin. In flash photolysis experiments, a quickly reacting component is always observed, in spite of the lack of dissociation into free dimers; this kinetic behavior is thought to reflect the presence of functionally independent alpha beta dimers, still connected by the flexible cross-link but forming an open hemoglobin tetramer. Two possible models for the interpretation of the kinetics of CO and/or haptoglobin binding are presented and discussed
Oxygen transport in extreme environments
No full textEvolution has adopted different strategies to solve the problem of transporting oxygen to respiring tissues, according to needs dictated by the environment. A thermodynamic analysis of haemoglobins of organisms living in extreme polar environments (mammals and fish) provides elegant examples of such adaptations
Adaptation to extreme environments: structure-function relationships in Emperor penguin haemoglobin
No full textThe functional properties of the single haemoglobin (Hb) of Emperor penguin (Aptenodytes forsteri) have been investigated at different temperatures as a function of proton and organic phosphate concentration. The complete amino acid sequence has been established. Comparison with that of human HbA shows 12 substitutions in the contact regions of alpha beta dimers. In addition to overall similarities shared with most of the avian Hbs previously described, this Hb shows significant differences, which could be related to the peculiar behaviour of this penguin. In particular we may consider that: (1) the shape of the Bohr effect curve seems well adapted for gas exchange during very prolonged dives, preserving penguin Hb from a sudden and not controlled stripping of oxygen; (2) the very minor enthalpy change observed at lower pH could be an example of molecular adaptation, through which oxygen delivery becomes essentially insensitive to exposure to the extremely low temperatures of the environment. Moreover, the small alkaline Bohr effect has been found to be only chloride-linked, since the pH dependence of the oxygen affinity is totally abolished in the absence of this ion. These functional characteristics are discussed on the basis of the primary structure of alpha and beta-chains
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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