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M Dautrevaux

Publications and source records attributed to M Dautrevaux.

At least 19 recordsLinked to original sources
PubMed1990

Steroid receptor exchange assay in the presence of acetonitrile: application to the study of glucocorticoid- and anti-glucocorticoid-receptor complexes.

Acetonitrile was used to modify the binding parameters of glucocorticoid-receptor complexes. Acetonitrile (8%) caused a striking increase of the rate constant of dissociation of non-transformed [3H]triamcinolone and [3H]RU 486 receptor complexes. The latter complexes appeared significantly less sensitive to acetonitrile than the former. Similar data were obtained for heat-transformed [3H]triamcinolone and RU 486-receptor complexes purified at a 90% relative homogeneity by DEAE-Trisacryl (diethylaminoethyl) chromatography. The rate constant of dissociation of both steroid-receptor complexes decreased after transformation. The dissociation of non-transformed receptor complexes by acetonitrile was reversible, and an exchange assay allowing 75% to 85% steroid exchange is described. However, the dissociation of transformed receptor complexes appeared completely irreversible and precluded the design of any exchange assay.

Acetonitriles↗
PubMed1979

Developmental aspect of phenylalanine hydroxylase in the rat -- hormonal influences.

Interpretations of the development of phenylalanine hydroxylase (PAH) in rat liver have been controversial, and the mechanism of ontogenic changes have not yet been elucidated. Fetal PAH activity at a gestational age of 21 days appeared to reach 32% that of adult male level at birth. The in vivo effectiveness of fetal PAH activity was correlated with enhancement of blood tyrosine, while amino-transferase activity appeared only after birth. No sex difference was noted in weaning rats, whereas, in adult females, PAH activity was only 42% that of males. Investigating hormonal influences on liver PAH activity we noted no change of enzyme activity following hydrocortisone, ACTH and estradiol treatment. However, 4 days of testosterone treatment in weaning female rats increased PAH activity (X1.7). Therefore, testosterone could explain increased PAH activity in adult males.

Adrenalectomy↗
PubMed1979

On the mechanism of the tetrahydropteridine cofactor oxidation in aerobic and H2O2-peroxydase media.

It is commonly postulated that the enzymatic hydroxylation of phenylalanine, tyrosine and tryptophan involves the concomitant oxidation of a tetrahydropteridinic cofactor to an unstable quinonoid product, converted to the initial compound under the catalytic action of dihydropteridine reductase. We now report UV, NMR, mass spectrum and spectroscopic studies of 2-amino-4-hydroxy-6,7-dimethyl-5, 6, 7, 8-tetrahydropteridine oxidation process either by atmospheric O2 or by the H2O2-peroxidase system. No quinonoid form was visualized and, moreover, the spectral characteristics of UV absorbance spectra, initially reported as specific for the quinonoid form, are related to other oxidation products whose formation is explained here.

Hydrogen Peroxide↗
PubMed1978

Phenylalanine analogues as inhibitors of phenylalanine-hydroxylase from rat liver. New conclusions concerning kinetic behaviors of the enzyme.

The conversion of phenylalanine to tyrosine is catalysed by phenylalanine-hydroxylase. The substrate phenylalanine shows two effects: (1) allosteric transition at low phenylalanine concentrations, (2) excess substration inhibition. The molecular structure of phenylalanine-hydroxylase has not yet been elucidated. However, a tetrameric structure has been proposed. The Kinetic analysis with respect to substrate analogues suggest the existence of three types of sites on each protomer: (1) a catalytic site, (2) a non-competitive inhibitory site, (3) a positive cooperative site. Use of the enzyme's natural cofactor, tetrahydrobiopterin, has been emphasized to ensure good interpretation of the kinetic results of the phenylalanine-hydroxylase effectors.

Allosteric Site↗
PubMed1977

Affinity labelling of human transcortin.

The binding site of transcortin has been studied by using bromoacetyltestosterone and bromoacetylated derivatives of progesterone which were monohydroxylated at different positions of the steroid nucleus. Specificity of affinity labelling was demonstrated by the displad cortisol analog was added to a [3H]cortisol-transcortin complex solution. The binding site crevice was found to be very narrow in the vicinity of the A and B rings of steroid since 2alpha-hydroxyprogesterone, 6alpha- or 6beta-bromoacetoxyprogesterone and dexamethasone could not displace bound cortisol. A specific affinity labelling was obtained with 11alpha-bromoacetoxyprogesterone, 16alpha-bromoacetoxyprogesterone and 17beta-bromoacetyltestosterone. The results of the affinity labelling by these hormone analogs suggested that one methionine and one histidine residues were located within the active site:methionine might interact with the 11beta-hydroxyl group and histidine with the 20 keto group of cortisol.

Affinity Labels↗
PubMed1977

[Sequential Edman degredation].

Since Edman's first publication in 1950, the stepwise degradation of proteins and peptides is universally performed by protein chemists. We extensively reviewed the different manual degradations. We take two examples of manual degradation: a semi-micromethod and a micromethod in order to illustrate the evolution of manual degradation. The "dansyl-Edman" procedure proposed by Hartley in 1963 completes the manual N-terminal determination of peptides. We describe the different procedures of identification of PTH-amino acids: paper chromatography, thin layer chromatography, gas chromatography and liquid chromatography under high pressure and various modified Edman degradation procedures. Possibilities and limits of the liquid phase Sequenator of Edman reported in 1967 and the solid phase Sequencer of Laursen reported in 1971 are also considered in detail.

Amino Acids↗
PubMed1977

A new experimental model of hyperphenylalaninemia in rat. Effect of p-chlorophenylalanine and cotrimoxazole.

A new experimental model of hyperphenylalaninemia was proposed. Combination of p.chlorophenylalanine, strongly inhibitor of phenylalanine hydroxylase, and cotrimoxazole, presumably inhibitor of dihydropteridine reductase, produced a good inhibition of phenylalanine hydroxylation in vivo. Thus phenylalaninemia reached values similar to those found in PKU patients, without administration of excess phenylalanine. Tyrosine concentrations remained near the control values and a phenylketonuria occurred.

Animals↗
PubMed1977

Amino acid sequence of a cyanogen bromide fragment containing the two tryptophanyl residues of lobster arginine kinase (Homarus vulgaris).

Lobster arginine kinase [EC 2.7.3.3] contains 2 tryptophanyl residues and 9 methionyl residues. The whole carboxymethylated protein was first subjected to CNBr cleavage and the resulting fragments were isolated by gel filtration and other experimental approaches. One fragment, CB5, which contains 60 residues including the two tryptophanyl residues and two of the five cysteinyl residues of the protein, was characterized and the results are reported inthis paper. The overall strategy for the establishment of the complete sequence of this fragment was based on the use of three types of peptides: (a) whole cyanogen bromide peptide CB5 which was partially characterized by automatic Edman degradation using a sequencer: 42 steps were performed out of 60 residues, (b) tryptic peptides of CB5, (c) peptides formed by cleavage of S-carboxymethylated arginine kinase (whole protein) at the two tryptophanyl residues with BNPS-skatole. The complete amino acid sequence of the CNBr polypeptide (CB5) which contains the two tryptophanyl residues of the whole protein was established.

Amino Acid Sequence↗
PubMed1977

Isolation and characterization of highly purified alpha-1-antitrypsin.

Highly purified human alpha-1-antitrypsin (phenotype MM) was obtained by an original method of preparative electrophoresis. The criteria of homogeneity were assured by one arc in crossed immunoelectrophoresis and one band on polyacrylamide gel. A unique N-terminal amino acid (pyroglutamic acid) and a unique C-terminal residue (lysine) were identified. Determined by gel electrophoresis, its molecular weight was 47,000 daltons.

Amino Acid Sequence↗
PubMed1976

[Bisalbuminaemia in pancreatitis: structural modifications of human serum albumin by proteolytic enzymes of the pancreas (author's transl)].

Bisalbuminaemia in pancreatitis is a transient abnormality related to the presence, on electrophoresis of the serum, of a fast-moving albumin; this abnormal form is also found, in large amounts, in the ascitic or pleural effusions of the patients. Experiments reported here indicate clearly that the fast albumin can be produced by a degradation of normal serum albumin by the proteolytic enzymes of the pancreas (chymotrypsin or elastase in association with carboxypeptidases A and B). Stuctural analysis of the isolated fast albumin of the patients shows that the C-terminal end of the molecule is different from normal serum albumin, which can be understood by a limited enzymatic degradation by chymotrypsin or elastase followed by the action of carboxypeptidases. The discovery of bisalbuminaemia in a patient affected by pancreatitis is suspicious of the presence of an ascitic or pleural effusion and of a pancreatic pseudo-cyst with a fistula emerging in the effusion.

Carboxypeptidases↗
PubMed1976

Localization of J-chain and interchain disulfide bonds in a human F(c)5mu-like fragment.

The inter H-H cysteinyl peptides and the localization of the J-chain were studied in a human F(c)5mu-like fragment. The latter was found to be built up by non-covalent association of molecular forms of 140 000, 95 000 and 70 000 dalton subunits. The trimeric, dimeric and monomeric forms were obtained from gradual reduction by dithiothreitol of the major component of 140 000 daltons, thus confirming the tetrameric nature of this subunit. The latter was found to result from the association of both components of the 70 000 dalton subunit, with the participation of the inter H-H subunit bridge. Structural analysis of the labelled peptides obtained by partial reduction and alkylation showed the presence of the intersubunit disulfide bridge and of the inter heavy-heavy chain bridge of the C-terminal region, and the absence of the heavy-heavy chain bridge of the hinge region. The sequence of these peptides is identical to the sequences of the corresponding peptides of normal mmu-chains. The J-chain, which was covalently linked to this F(c)5mu-like fragment, was found to be predominantly associated within the 95 000 dalton subunit. The results showed that the J-chain was linked in the protein as a "clasp" within a single subunit and not between two subunits.

Amino Acid Sequence↗
PubMed1976

Comparison of the amino acid sequence of pig heart myoglobin with other ungulate myoglobins.

The primary structure of pig heart myoglobin has been established by study of the tryptic peptides of whole globin and by analysis of the fragments obtained by CNBr cleavage. Thermolysin and chymotrypsin digestion were used to determine the sequence of the M fragment (56-131). Automatic Edman degradation of whole globin and of the M fragment completed the sequence of pig myoglobin. Comparison with other ungulates shows that pig myoglobin is far from other artiodactyls previously studied (ox and sheep) and close to the eutherian ancestral chain.

Amino Acid Sequence↗
PubMed1976

Studies of human transcortin at different pHs: circular dichroism, polymerisation and binding affinity.

The transcortin we have used in this work is extremely pure. This was shown by the polymerisation observed at pH 4. This polymerisation is never observed with an impure form of transcortin [4]. Moreover, since it is known that the presence of cortisol in the binding site is an essential condition to the activity of purified transcortin [5], it appears that a correlation between the secondary structure and the biological activity of the transcortin exists. The results we have obtained are summarized below: (1) The inhibition of the transcortin binding capacity essentially takes place between pH 5 and 4. (2) A reorganisation of the structure of the protein moiety is observed between pH 6.5 and 5.9. (3) A decrease of the helicity ratio is observed between pH 5 and 4. It appears therefore that, in the limits of experimental accuracy of CD measurements to determine the amount of beta-structure, no appreciable change of binding activity is taking place after the appearance of a large percentage of beta-structure between pH 6.5 and 6. On the other hand, the sudden decrease of protein activity at low pH is likely to be correlated with the disappearance of a well-defined helical region. Other biochemical and physical experiments would be of course necessary, in order to precise this first observation of a structure-function relationship in transcortin.

Binding Sites↗
PubMed1976

The covalent structure of dog myoglobin.

The primary structure of the myoglobin of the domestic dog (German shepherd) was studied. Tryptic and thermolytic peptides were compared with the sequence of other known myoglobins; the stepwise automatic Edman's degradation of the whole globin and also the chymotryptic digestion of the median fragment obtained by CNBr cleavage completed this sequence. Comparison of the established dog myoglobin structure with those from other carnivora shows 16 differences versus badger, 20 versus harbour seal and 15 versus California sea lion.

Amino Acid Sequence↗