RESUMEN
The arrangement of peptides which form the hinge region in Fab-Fc recombinant immunoglobulins, restored artificially from Fab and Fc fragments was approached by computation. The architecture of this region in the symmetric (Fab')2-Fc derivatives and in the asymmetric (Fab')1-Fc differs to a considerable extent. In (Fab')2-Fc species but not in (Fab')1-Fc the preferable arrangement appeared to be stabilized predominantly by the mutual interaction of symmetric hinge peptides. It was concluded that the resulted by this interaction rotational restrictions may eventually induce the structural transformations in the molecule, influencing the effector activity of Fc.
Asunto(s)
Fragmentos Fab de Inmunoglobulinas , Fragmentos Fc de Inmunoglobulinas , Región de Unión de la Inmunoglobulina , Secuencia de Aminoácidos , Animales , Microscopía Electrónica , Datos de Secuencia Molecular , Péptidos , Conformación Proteica , Conejos , Proteínas Recombinantes , TermodinámicaRESUMEN
An electrochromatographic method for the analysis of sera is described with particular design to studies of abnormal proteins. The method allows a simultaneous but independent evaluation of molecular weight and charge related migration of proteins. A modification which may improve the analysis of immunoglobulins by increasing their electrophoretic mobility is described.
Asunto(s)
Proteínas Sanguíneas/análisis , Cromatografía en Gel/métodos , Electroforesis en Papel/métodos , Electroforesis en Papel/normas , Estudios de Evaluación como Asunto , Humanos , Inmunoglobulina A/análisis , Inmunoglobulina G/análisis , Mieloma Múltiple/análisisRESUMEN
Immunoglobulin species, recombined from Fab and Fc fragments with anti-red cell specificity were used as cytophilic antibodies in studies of triggering the effector activity of immunoglobulins. Recombinant immunoglobulins containing a single Fab' appeared inactive in binding to cell receptors and triggering antibody dependent cellular cytotoxicity, while those with two Fab' exhibited an activity comparable to intact antibody IgG. The experiments indicate that Fab fragment may interact with Fc and inhibit its binding to cell receptors.
Asunto(s)
Fragmentos Fab de Inmunoglobulinas/inmunología , Fragmentos Fc de Inmunoglobulinas/inmunología , Fragmentos de Inmunoglobulinas/inmunología , Citotoxicidad Celular Dependiente de Anticuerpos , Sitios de Unión , Humanos , Técnicas In Vitro , Receptores Fc/inmunología , Formación de RosetaRESUMEN
Antibody-like molecules were formed by artificial recombination of proteolytic IgG fragments (Fab' with anti-SRBC activity, and Fc) and used for studies concerning the complement fixation. Such molecules, when composed of single Fab' bound to Fc fragment appeared inactive, while species containing two Fab' fragments revealed the hemolytic activity. The results were discussed and interpreted, assuming that the interaction of Fab domains with CH2 domains in the Fc fragment is a main structural effect influencing the binding of the complement.
Asunto(s)
Eritrocitos/inmunología , Hemólisis , Fragmentos Fab de Inmunoglobulinas , Fragmentos Fc de Inmunoglobulinas , Animales , Sitios de Unión de Anticuerpos , Pruebas de Fijación del Complemento , Humanos , Fragmentos Fab de Inmunoglobulinas/aislamiento & purificación , Fragmentos Fc de Inmunoglobulinas/aislamiento & purificación , Técnicas In Vitro , Conejos , OvinosAsunto(s)
Disulfuros/farmacología , Inmunoglobulina G , Inmunoglobulina M/clasificación , Péptido Hidrolasas/farmacología , Animales , Quimera , Pruebas de Fijación del Complemento , Reactivos de Enlaces Cruzados/farmacología , Pruebas de Hemaglutinación , Humanos , Fragmentos Fab de Inmunoglobulinas , Fragmentos Fc de Inmunoglobulinas , Inmunoglobulina G/biosíntesis , ConejosAsunto(s)
Antígenos , Inmunoglobulina G/inmunología , Albúmina Sérica/inmunología , Biopolímeros , Fenómenos Químicos , Química , Cromatografía en Gel , Disulfuros , Electroforesis en Gel de Agar , Electroforesis en Gel de Poliacrilamida , Humanos , Métodos , Albúmina Sérica Bovina/inmunología , Compuestos de Sulfhidrilo , ZincRESUMEN
Excessive production of IgM in macroglobulinemia is accompanied frequently by secretion of proteins and peptides which are normally absent from biological fluids. These proteins and peptides are probably secreted by cells producing IgM. Three types of peptides were isolated and their basic properties are described. One peptide showed calcium-binding properties, and the other two peptides were bound to secreted IgM immunoglobulin.
Asunto(s)
Inmunoglobulina M/metabolismo , Péptidos/metabolismo , Macroglobulinemia de Waldenström/metabolismo , Aminoácidos/análisis , Carbohidratos/análisis , Humanos , Péptidos/análisis , Péptidos/orina , Unión ProteicaRESUMEN
It was found that intravenous application of thiosulfate increased non-specifically immunoglobulin concentration in mice sera. Thiosulfate stimulated the immune response to T-dependent antigens.
Asunto(s)
Formación de Anticuerpos/efectos de los fármacos , Tiosulfatos/farmacología , Animales , Proteínas Sanguíneas/metabolismo , Disulfuros , Ratones , Oxidación-Reducción , Compuestos de Sulfhidrilo , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunologíaRESUMEN
Sodium thiosulphate injected i.v. into mice causes a marked increase in concentration of several serum proteins, particularly immunoglobulins. When given together with antigen, it significantly potentiates the T-dependent humoral responses.
Asunto(s)
Inmunoglobulinas/biosíntesis , Tiosulfatos/inmunología , Animales , Proteínas Sanguíneas/biosíntesis , Sinergismo Farmacológico , Femenino , Inmunoglobulina A/biosíntesis , Inmunoglobulina M/biosíntesis , Masculino , Ratones , Ratones Endogámicos BALB C , Tiosulfatos/administración & dosificaciónRESUMEN
An acidic glycoprotein with calcium-binding properties was isolated from the urine of patients with severe macroglobulinaemia IgM. The molecular weight of this protein determined by Sephadex gel filtration was found to be 62 000 +/- 2800 in Tris - HCl buffer and 21 000 +/- 1000 in 6 M guanidine - HCl. The amino acid and carbohydrate composition of the isolated glycoprotein is presented. Electrophoretic migration of this protein was observed to be greatly affected by calcium ions present in the buffer in a concentration of 10(-3) M. At least two sets of binding sites seem to participate in binding calcium. The values 2.2 - 10(6) M-1 for the apparent association constant and 4.4 - 10(-4) mol of Ca2+ bound per g of protein for high affinity bindings sites were estimated, on the basis of data from the equilibrium dialysis. The origin and possible biological role of this protein is discussed.
Asunto(s)
Calcio/metabolismo , Proteínas Portadoras , Glicoproteínas , Inmunoglobulina M/metabolismo , Macroglobulinemia de Waldenström/metabolismo , Aminoácidos/análisis , Carbohidratos/análisis , Proteínas Portadoras/metabolismo , Glicoproteínas/metabolismo , Humanos , Inmunodifusión , Inmunoelectroforesis , Cinética , Sustancias Macromoleculares , Peso Molecular , Ácidos Siálicos/análisisRESUMEN
It has been suggested that the low disulfide interchange activity in cells producing IgM causes the excretion of immunoglobulin molecules with deficient disulfide cross-linking. IgM material found in the serum formed aggregates which were stabilized largely by noncovalent bonds. Sedimentation coefficients of these aggregates ranged from 11 to 19 S and were similar to sedimentation coefficients calculated for molecules composed of 2, 3, 4 and 5 IgM subunits. A fraction corresponding to a single IgM subunit with a sedimentation coefficient 7.1 S was also present in the serum. The molecular weight of this fraction, determined in mild conditions by Sephadex gel filtration, appeared higher than that predicted for IgMs, reaching the value of 270 000-280 000. The evident increment of molecular weight, compared to a single IgM subunit, was attributed to glycopeptides of sedimentation coefficient 2 S, which form the complex with IgMs molecules. These glycopeptides were also present in aggregates consisting of more than one IgM subunit. The number of IgM subunits participating in aggregates and their molecular weights appeared to depend on the ratio of 2 S glycopeptides to IgM material. With the increase of this ratio the molecular weight of the aggregates lowered and vice versa. Electrical charge and some physico-chemical properties of the aggregates were also significantly affected by the presence of glycopeptides, 2 S glycopeptides were supposed to be the basement membrane related material. Suggestions concerning the interpretation of the phenomenon are presented and discussed.
Asunto(s)
Inmunoglobulina M , Macroglobulinemia de Waldenström/inmunología , Aminoácidos/análisis , Sitios de Unión , Disulfuros/análisis , Humanos , Inmunodifusión , Inmunoelectroforesis , Inmunoglobulina M/metabolismo , Sustancias Macromoleculares , Peso Molecular , Unión ProteicaRESUMEN
Sodium thiosulfate was used to enhance in vivo the polymerization of myeloma IgM, deficient in disulfide cross-links. The therapy sharply decreased the amount of low molecular weight IgM fractions, while increasing the serum content of molecules of higher molecular weight. The degree of disulfide cross-linking in IgM increased under the influence of thiosulfate. The rate of secretion into the serum and urine of some membrane-related glycopeptides and species rich in sialic acid was reduced. Also, the discharge of L chains to the urine was lowered during the thiosulfate trial. All these changes were attributed to enhancement of disulfide-interchanging enzyme activity by thiosulfate.