A low molecular weight compound, which inhibits the G1-S transition in rat hepatocytes, was obtained by tryptic hydrolysis of human alpha 2-macroglobulin followed by ultrafiltration at pH 10. It was purified by high-performance liquid chromatography on mu Bondapak C18 and mu Bondapak NH2 with a practically quantitative yield; from 5.1 g of alpha 2-macroglobulin, 2.8 micrograms of purified compound were recovered. Inactivation by specific enzymes and chemical analyses showed that the inhibitor is a sialylated glycopeptide whose peptide moiety contains a pyroglutamyl residue. Its molecular mass, estimated by gel permeation chromatography, would be in the interval 3,500-4,600. However, amino acid analyses indicated that it is not yet pure. All these data suggest that alpha 2-macroglobulin could be the carrier of the precursor form of the glycopeptide.

Amino Acids↗

PubMed1987

Synthesis and biological activity of eight thymulin analogues.

Eight analogues of thymulin, a thymic nonapeptide involved in several aspects of T-cell differentiation, were synthesized by the conventional method in solution. Four were modified in residue 7 (Ala, D-Ala, D-Leu or Sar instead of Gly) and two in residue 8 (D-Ser or Thr instead of Ser); in the others, the Gly6-Gly7 sequence was replaced either by a single glycyl residue or by a triglycyl sequence. The biological activity of the analogues was determined in the rosette assay: five exhibited a prolonged activity in vivo with respect to thymulin. All the analogues inhibited the binding of tritiated thymulin to thymulin receptors on three human lymphoblastoid T-cell lines (HSB2, 1301 and CEM) with the same order of magnitude as non-labelled thymulin.

Amino Acids↗

PubMed1984

Synthesis of tritiated tuftsin and macrophage inhibitory tripeptide via acetylenic intermediates.

Acetylenic analogues of tuftsin (Thr-Dah-Pro-Arg) and of a macrophage inhibitory tripeptide (Thr-Dah-Pro) have been synthesized by conventional procedures in solution (Dah = 2,6-diamino-4-hexynoic acid). These acetylenic derivatives are intermediates for the preparation of structurally unmodified, tritiated peptides. Catalytic tritiation of Thr-Dah-Pro-Arg and of Thr-Dah-Pro has afforded the radioactive tetra- and tripeptides with specific activities of 11.4 Ci/mmol and 37 Ci/mmol, respectively.

Acetylene↗

PubMed1983

Partial purification of rat and human serum factors inhibiting the G1-S transition in rat hepatocytes.

A low molecular weight compound, which inhibits the G1-S transition in rat hepatocytes, was purified from rat trypsin-treated serum by DEAE-cellulose chromatography and high-performance liquid chromatography on three different stationary phases. This procedure led to a 34500-fold purification with a 29% yield. Inactivation of the purified material by specific enzymes showed that the inhibitor is a glycopeptide containing a peptide moiety, N-acetylneuraminic acid and galactose residues. Amino acid analyses indicated the possible existence of a pentapeptide structure. The same purification procedure was applied to the corresponding human inhibitor. Inactivation by specific enzymes showed that it is also a glycopeptide.

Amino Acids↗

PubMed1982

Synthesis of an immunogenic conjugate and of two 125I-labelled derivatives of the "facteur thymique sérique".

[4-Aminobenzoyl-Gln1]FTS was synthesized from a suitably-protected derivative of the "facteur thymique sérique" (FTS). It was diazotized and coupled to bovine serum albumin, yielding an immunogenic conjugate in which all the functional groups of the peptide remained intact. [4-Aminobenzoyl-Gln1]FTS and another synthetic ćompound, [3-(4-hydroxyphenyl)propionyl-Gln1]FTS, were 125I-labelled. The binding of these radioactive peptides of the anti-FTS antibodies obtained with our immunogenic conjugate was inhibited by unlabelled FTS.

Animals↗

PubMed1980

Synthesis of analogs of the serum thymic nonapeptide, "facteur thymique serique" (FTS). Part II.

New analogs of FTS (Facteur Thymique Sérique), less than (Formula: see text), a circulating thymic factor, were prepared by replacing the amino acid residues in positions, 1, 3, 4, 5, 6 and 3 and 6 together. Five other analogs of C-terminal heptapeptide were prepared by replacing the amino acid residues in position 3 or 6. These peptides were synthesized using conventional synthesis in solution.

Amino Acid Sequence↗

PubMed1979

Synthesis of analogs of the serum thymic nonapeptide, "facteur thymique serique" (FTS). Part I.

Analogs of FTS (Facteur Thymique Sérique), less than :formula: (see text), a circulating thymic factor, were prepared by replacing the amino acid residues in positions 1, 2, 8 and 9, or by shortening the nonapeptide chain at the N- or C-terminal end. These peptides were synthesized by two different schemes using the conventional synthesis in solution.

Amino Acid Sequence↗

PubMed1965

[Typhoid fever, hemoglobinuria and glucose-6-phosphate dehydrogenase deficiency. (Apropos of 2 cases)].

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Adolescent↗