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Biomedical subjects

A Delmas

Publications and source records attributed to A Delmas.

At least 37 records · Page 2Linked to original sources
PubMed1995

Purification of synthetic peptide libraries by affinity chromatography using the avidin-biotin system.

The specific interaction between biotin and avidin was exploited in the affinity purification of solid-phase synthesized peptide libraries. During peptide library synthesis, by means of the single-resin method in which coupling on variable positions is carried out using an equimolar mixture of amino acids, biotin was used to cap the unreacted amino groups remaining after coupling of the equimolar amino acid mixture. The following synthesis and deprotection procedures were performed as usual in tert,-butyloxycarbonyl chemistry. The purification of the peptide mixture containing N-biotinylated sequences was performed by affinity chromatography on an avidin-agarose column. The unwanted terminated sequences were retained in the avidin column while the purified peptide mixture was eluted as indicated by reverse-phase HPLC and MS analysis monitoring. The avidin column was regenerated and the biotinylated sequences were released under reversible denaturing conditions. The usefulness of biotinylation for peptide library purification is demonstrated here for the first time for a peptide mixture containing by-products that cannot be separated from the mixture by classical HPLC purification. This purification technique could be applied to all syntheses, presenting difficult reacting steps.

Amino Acid Sequence↗
PubMed1994

Influence of the conformation of a macromolecule on the generation of T-cell proliferative response. A study with model polypeptides.

To study the influence of the conformation of polypeptidic macromolecules on the generation of T-cell epitopes, sequential polypeptides with an octamer repeat unit were designed and synthesized. They adopt mainly unordered and alpha-helical conformations. Among these polypeptides, those containing proline are fully or partly unordered, and are more effective at inducing T-cell proliferation than a proline-free very stable alpha-helical polypeptide. This extremely stable alpha-helical conformation, probably stabilized by aggregation, would enhance its stability against proteolytic processing.

Amino Acid Sequence↗
PubMed1990

[Anatomy today].

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Aging↗
PubMed1989

Neutralization of cholera toxin by rat IgA secretory antibodies induced by a free synthetic peptide.

Secretory immunoglobulin A (sIgA) is the major immunoglobulin in the bile of several species. They contribute to local immune defences of the gut. The protection against cholera toxin (CT) is due to the presence of specific sIgA in the bile and in the gut. We have already reported that oral administration of the peptide corresponding to the sequence 50-75 of cholera toxin B subunit elicits serum antibodies neutralizing CT activity, and that IgA and local protection are observed in the intestine of P50-75 orally immunized mice. In this study, we demonstrate the potential of this synthetic peptide as immunogen without carrier or adjuvant, not only in a strain known to be sensitive to CT, but also in an outbred one. Furthermore, this peptide stimulates the mucosal immunity, since we show that P50-75 induced-sIgA purified from rats bile and serum, are capable of neutralizing CT activity in the in vivo intestinal ligated loop test.

Animals↗
PubMed1989

Oral immunization with a free peptide from cholera toxin: local protection and IgA production.

It is frequently of great benefit for good protection against pathogens to elicit a local immunization. For example the importance of antibacterial as well as antitoxin local secretory IgA, for protection against cholera, has been underlined in several studies. We have already reported that oral administration of the peptide corresponding to the 50-75 sequence of cholera toxin (CT) B subunit elicits serum antibodies neutralizing CT activity. In this study we demonstrate that IgA with specificity to CT are present in intestinal secretions of mice immunized orally with the P50-75 or P30-50 peptides of CT B subunit. In addition local protection is observed in the intestine of P50-75 orally immunized mice. These results point out the potential of synthetic peptides as immunogens at the mucosal level.

Administration, Oral↗
PubMed1987

Synthesis of a new carrier for immunization: polytuftsin. Two examples of its use with peptides selected in the hepatitis B surface antigen.

Sequential poly(Arg-Thr-Lys-Pro) consisting mainly of the repeat of tuftsin Thr-Lys-Pro-Arg was synthesized by condensing the p-nitrophenyl ester of Arg(HCl)-Thr-Lys-(2-Cl-Z)-Pro in the presence of HOBt. Two haptenic sequences of the Pre-S region of hepatitis B virus antigen (10-26 and 39-55) were prepared by solid phase and coupled to polytuftsin via glutaraldehyde. The peptides, either free or coupled to polytuftsin, were administrated to mice and the antisera were assayed by ELISA. Coupling the peptides to the polypeptide significantly improved the anti-peptide antibody titer in Freund complete adjuvant or in NaCl 0.9%. Cross-reaction between antibodies induced by the peptides and the native protein was also improved. Polytuftsin alone is very poorly immunogenic.

Animals↗
PubMed1986

Oral immunization with a synthetic peptide of cholera toxin B subunit. Obtention of neutralizing antibodies.

The ability of free synthetic fragments of the cholera toxin (CT), administered by parenteral or oral route, without adjuvant, to induce antibodies cross-reacting with CT was tested. Two peptides corresponding to the sequences 30-50 and 50-75 of the CT beta chain were selected and synthesized. Both free peptides, given intraperitoneally or orally, without adjuvant, elicited seric antibodies cross-reacting with CT. The anti-(P50-75) antibodies were able to neutralize the CT activity. Our results show that protection against a toxin at the systemic level can be obtained with a synthetic peptide even when administered by an oral route.

Administration, Oral↗
PubMed1985

Epitopes of the 44-68 human parathyroid hormone fragments: the importance of specific hydrophilic peptide sequences.

Several pentapeptides included in the 44-68 sequence of human parathyroid hormone (hPTH) were synthesized simultaneously on benzhydrylamine and m-nitrobenzhydrylamine resins. The first polymer gave the free peptide and the second the peptidyl-resin complex. An ELISA test carried out with each peptidyl-resin complex showed that all the anti-44-68 hPTH antibodies raised in different animal species are directed against the same hPTH pentapeptidic sequence. This sequence is very hydrophilic and is specific to the hormone. This study demonstrates the importance of specific peptide chains in an epitope.

Amino Acid Sequence↗
PubMed1985

Solid phase synthesis of two cholera toxin B subunit antigens.

The 30-50 and 50-75 sequences of the cholera toxin beta chain including the amino-acids that are thought to be involved in toxin-receptor binding have been synthesized using the solid phase method. They were then purified by gel permeation and ion exchange chromatography. Both these free peptides induced serum antibodies recognising the native toxin after oral or intraperitoneal administration. Only the antibodies raised against the 50-75 peptide, however, were able to neutralize toxin activity.

Animals↗
PubMed1980

[Not Available].

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Anatomy↗