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PubMedDate not supplied

[Effect of perturbing agents on the dynamic properties of immunoglobulin fragments].

The effect of NaCl, (NH4)2SO4, sodium dodecylsulphate and temperature on conformational properties of light-chain dimers and the Fab-fragments of immunoglobulins G has been investigated using the spin-label method. All these agents despite their different nature, induce qualitatively the same shift in the equilibrium between the A- and B-states of spin label towards the state of higher microviscosity A. The effect of 1.2 M NaCl and 0.75 M (NH4)2SO4 increase the stability of IgG in relation to temperature, as a result of this shift. The data obtained are interpreted in terms of the dynamic model of protein behaviour in water suggested earlier. In accordance with the model the action of the agents perturbing the conformation of protein and the ordered structure of water in the non-polar cavities of protein, reduce the life-time of this cavities in the water accessible state.

Ammonium Sulfate↗
PubMed1978

Interaction of immunoglobulin fragments with the mammalian sperm acrosome.

A study was made of the interaction of immunoglobulins and immunoglobulin fragments from sera of rabbits and pigs with the acrosomes of ten species of mammalian spermatozoa to investigate previous reports of an interaction between normal serum and the acrosome. It was shown that this could be predominantly attributed to IgC, although there was weak staining due to IgM. Further, it was shown that IgG interacted through the Fc fragment, the Fab fragment causing only weak staining of homologous spermatozoa.

Acrosome↗
PubMed1975

Serum disappearance and catabolism of homologous immunoglobulin fragments in rats.

The serum disappearance, metabolic clearance and whole body catabolism of homologous immunoglobulin fragments were studied in rats. The rapid disappearance of Fab fragments from serum in normal animals was no longer present after nephrectomy. In contrast, the serum disappearance curve of Fc fragments was not altered by nephrectomy. The results of three different experiments, however, indicated that similar to Fab fragments, some Fc fragments underwent filtration and degradation in the kidneys. First, the amount of intact Fc fragments excreted in the first day after injection increased from 6% of the injected dose in normal rats to 17% in rats pretreated with sodium maleate. Secondly, nephrectomy eliminated the rapid phase of whole body catabolism of inected Fc fragments. Thirdly, auto-radiographic studies showed localization of Fc fragments in the renal proximal tubule cells in the first 3 hr after injection. An identical localization was seen with Fab fragments. These results support the conclusion that removal from circulation by glomerular filtration and subsequent reabsorption and degradation in proximal tubule cells represent the major mechanism for catabolism of Fab fragments. Although some Fc fragments undergo the same fate, most injected Fc fragments equilibrate with unknown sites where they are possibly bound and made unavailable for filtration in the kidneys.

Animals↗
PubMed1981

[Immunoglobulinic fragments of urinary proteins in patients affected by acute pneumonopathies, lung cancer and tuberculosis (author's transl)].

This study reports the immunoelectrophoretic analysis performed on 95 samples of urinary proteins. This analysis shows that in the majority of cases the migrant proteins in gamma position are F(ab) and Fc fragments, and free light chains with a molecular weight between 70,000 and 10,000. There is evidence of an increase in the immunoglobulinic fragments during inflammatory processes and their disappearance afterwards. This phenomenon proves that the elimination of these fragments evidences an increased synthesis of immunoglobulins and consequently also an increased catabolism.

Acute Disease↗
PubMed1984

Immunoglobulin fragments, F(ab')2, that are cytotoxic to enzyme-treated cells.

Bivalent immunoglobulin fragments of IgG, F(ab')2, prepared from normal murine sera were found to be cytotoxic to neuraminidase-treated cells. The fragments were cytotoxic to both allogenic and syngeneic targets (with respect to the source of the sera), suggesting that the antigen bound by the F(ab')2 is not related to the major histocompatibility locus of mice (H-2).

Animals↗
PubMed1992

Crystal structure of human immunoglobulin fragment Fab New refined at 2.0 A resolution.

The three-dimensional structure of the human immunoglobulin fragment Fab New (IgG1, lambda) has been refined to a crystallographic R-factor of 16.9% to 2 A resolution. Rms deviations of the final model from ideal geometry are 0.014 A for bond distances and 3.03 degrees for bond angles. Refinement was based on a new X-ray data set including 28,301 reflections with F > 2.5 sigma(F) from 6.0 to 2.0 A resolution. The starting model for the refinement procedure reported here is from the Brookhaven Protein Data Bank entry 3FAB (rev. 1981). Differences between the initial and final models include modified polypeptide-chain folding in the third complementarity-determining region (CDR3) and the third framework region (FR3) of VH and in some exposed loops of CL and CH1. Amino acid sequence changes were determined at a number of positions by inspection of difference electron density maps. The incorporation of amino acid sequence changes results in an improved VH framework model for the "humanization" of monoclonal antibodies.

Amino Acid Sequence↗
PubMed1983

Stimulation of the Na/K pump in LK sheep erythrocytes by immunoglobulin fragments.

Alloimmune antiserum against the L antigen of red cells from sheep of the LK phenotype is known to stimulate by several fold active Na/K transport in LK cells. We have shown that monomeric fragments, Fab1, of anti-L, as well as dimeric fragments, F(ab1)2, stimulate transport to the same extent as intact anti-L Ig. Special care was taken to obtain pure fragments. Two earlier reports on the effect of immunoglobulin fragments were contradictory.

Animals↗
PubMed1989

[Immunobiological activity of platinum coordination compounds in a complex with immunoglobulin fragments].

The investigation of biological activity of two coordination platinum (II) compounds covalently linked with Fab-fragments of nonspecific immunoglobulin donors on mononuclears of peripheral man blood in vitro and blood elements of mice BALB/c has been done in this paper. There have been stated the decrease of cytotoxic activity of platinum reagents after complexing and modulating influence of platinum-globulin complexes on immunocompetent cells. The prospects of increasing biological activity of immunological preparations on the basis of directed modification by platinum reagents has been also discussed.

Adjuvants, Immunologic↗
PubMed1979

Crossed immuno-electrodiffusion in the diagnosis of immunoglobulin fragment abnormalities.

The use of crossed immuno-electrodiffusion in the diagnosis of alpha-chain disease is described. The same basic technique is applicable in diagnosis of diseases in which immunoglobulin fragment abnormalities may occur. Crossed immuno-electrodiffusion is shown to be a superior method for demonstrating the abnormaility by providing more powerful resolution. Immunoselection (an adaptation of the classical method of immuno-electrophoresis) or rocket immuno-electrodiffusion both have limitations which are overcome by the use of crossed immuno-electrodiffusion. Mixture of antibodies is avoided by separating antibody-containing gels with interposition of intermediate gel layers free of antibody. Furthermore, precipitin rockets of some specific proteins can also be identified morphologically.

Electrophoresis, Cellulose Acetate↗
PubMed1993

Bacterial expression of immunoglobulin fragments.

The expression of Ig fragments in Escherichia coli permits rapid access to engineered molecules with antigen-binding properties. While the expression in a functional state by secretion to the periplasm is the standard method for the production of Fv and Fab fragments, single chain Fv fragments are mainly produced by refolding from insoluble aggregates. Although all of these Ig fragments serve as valuable aids in the study of antigen binding, their different biochemical properties must be considered when using them as research tools or for medical applications. In addition to these simple univalent antibody fragments, the bacterial expression of bivalent and bispecific versions and of hybrid proteins with novel effector functions is gaining increasing importance.

Animals↗