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S Elsayed

Publications and source records attributed to S Elsayed.

106 records · Page 6Linked to original sources
PubMed1979

The allergenic structure of allergen M from cod. III. Studies on the antigenicity of long-sequence peptides.

Fragments TM 1 (75 amino acid residues) and TM 2 (38 amino acid residues), and 3 other polypeptides (range 16-25 amino acid residues) of Allergen M from cod were shown to be active in rabbit IgG-mediated reactions. The same peptides were previously found to possess reactivity in IgE-mediated reactions, thus suggesting a structural relationship between their antigenic and allergenic determinants.

Absorption↗
PubMed1979

The indirect rat mast cell degranulation test reconsidered.

The indirect rat mast cell degranulation test for the detection of human reaginic antibodies was reinvestigated. When the mast cells were incubated with human reaginic serum at concentrations exceeding approximately 3%, a massive, non-specific histamine release occurred, irrespective of the presence or absence of allergen. At tolerated serum concentrations (below 3%), the allergen concentration did not influence the release process. We conclude that the indirect rat mast cell test is not applicable as an alternative test system for the study of immediate hypersensitivity in humans.

Allergens↗
PubMed1978

Crossed immunoelectrophoretic and crossed radioimmunoelectrophoretic studies employing a model allergen from codfish.

A standard reference pattern in crossed immunoelectrophoresis (CIE) of the parvalbumin fraction of a cod white muscle extract was established. Crossed line immunoelectrophoresis (CLIE), tandem CIE and crossed radioimmunoelectrophoresis (CRIE) were used to identify the major allergens, thereby establishing a basis for future work employing quantitative immunoelectrophoretic techniques in the study of codfish allergens. Rocket immunoelectrophoresis and rocket-line immunoelectrophoresis were used to demonstrate antigenic determinants on polypeptide fragments of the major allergen, Allergen M. The results show the usefulness of these techniques in studies of antigenic determinants on non-precipitating polypeptides. CRIE with 8 patients's sera showed radiostaining indicating IgE binding corresponding to at least 7 precipitates in the crude extract CIE preparations. The purified DS 22 fraction was shown to contain 2 CRIE-positive (IgE-binding) precipitates. When using Allergen M, these precipitates were also demonstrated, one of them in trace amounts only.

Allergens↗
PubMed1977

Allergenic structure of allergen M from cod. II. Allergenicity of the limited tryptic hydrolysis peptides of fragment TM 2.

The peptides P1B3 (amino acid residues No. 88-113) and LT3N1 (residues No. 88-108), obtained from the limited tryptic hydrolysis of fragment TM 2 from codfish allergen M inhibited the interaction between allergen M and reaginic IgE antibodies both in vitro (87 and 62% RAST inhibition, respectively) and in vivo (total PK test inhibition). The peptide A7B1 (residues No. 97-113) overlapping the former at the COOH-terminus, was inactive in PK test inhibition experiments and produced only a minor inhibition of RAST (15%). The findings suggest that the nonapeptide residue No. 88-96 is partially indispensible for the allergenic activity of fragment TM 2, and is likely to incorporate allergenic determinant(s).

Allergens↗
PubMed1976

The allergenic structure of allergen M from cod. I. Tryptic peptides of fragment TM 1.

In attempts to locate the allergenic active sites of fragment TM 1 of allergen M from cod, the allergenicity of the tryptic hydrolysis peptides was examined both in vivo and in vitro. A duodecapeptide (residues No. 33-44) was tentatively suggested to incorporate at least one allergenic determinant. All the tryptic peptides were less active than allergen M as shown by the in vivo titration experiments. The activity of the peptides was not due to contamination of intact allergens.

Allergens↗
PubMed1975

The primary structure of allergen M from cod.

The complete primary structure of allergen M of cod (Gadus callarias L.) is presented. The amino acid sequence of fragment TM1, the NH2-terminal peptide of allergen M, was elucidated by the dansyl-Edman method. It consists of 75 amino acids and 1 glucose residue (mol. wt. 8,492). By summation of the sequence data of fragment TM1 and the previously reported fragment TM2, the intact allergen M has 113 residues (mol. wt. 12,328). Fragment TM1 of cod shows less homology (30.6 percent) with the corresponding fragments of other reported fish species than does fragment TM2 (42.1 percent); the intact allergen M shows 34.5 percent homology. The single half cystine of allergen M was shown to be blocked. Gas chromatographic analysis of the reduced and nonreduced allergen M suggested that the glucose is bound to Cys 18 through an S-glucosidic bond.

Allergens↗
PubMed1975

Physico-chemical properties and specific activity of a purified allergen (codfish).

The major allergen (Allergen M) from codfish is an acidic protein, mol. wt. 15000 with 114 amino acid residues and only one sugar (glucose) residue. It is highly active in skin testing on codfish-allergic individuals, in passive transfer (PK) testing and in the radioallergosorbent test (RAST). The activity resists denaturation and incomplete tryptic hydrolysis. Two fragments (TM 1, mol. wt. 8500, and TM 2, mol. wt. 6500) are obtained from allergen M. The fragments are equally active and allergenically identical in biological tests, but somewhat less active than Allergen M itself. Smaller peptides obtained from TM 2 are inactive. The amino acid sequence of TM 2 is given as the first reported example of a full structural analysis of an active allergen. The information obtained in studies of this model allergen is compared with information published from other studies of allergens. Similarities and differences are pointed out.

Allergens↗