Biomedical subjects
Publications and source records attributed to G Biserte.
Human serum was submitted to a one step displacement-ligand exchange chromatography. Displacement removed serum albumin and part of gamma-globulins. Ligand exchange furnished an enriched heme-hemopexin fraction. An original, non denaturing human heme-hemopexin preparation is proposed.
The complete amino acid sequence (125 residues) of sea urchin histone H2A has been established by structural studies of peptides derived from tryptic and chymotryptic cleavage of the maleylated protein and from thermolysin cleavage of the intact protein. By comparison with calf homologous histone, the basic amino-terminal and carboxy-terminal parts of the protein show 11 substitutions and 4 deletions. The remainder of the sequence, mostly hydrophobic, is almost completely unchanged.
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Two electrophoretic forms of rat alpha-fetoprotein were purified using immunosorbent chromatography and preparative electrophoresis on polyacrylamide gel slabs. Some of their respective chemical properties and their affinity for the Ricinus communis lectin (RCAI) were compared. Electrophoresis on polyacrylamide gradient gel in the presence of sodium dodecyl sulfate indicated a slight difference in molecular 74 000 for the slow alpha-fetoprotein (AFPA) and 72000 for the fat alpha-fetoprotein (AFPB). no significant difference in amino acid composition between AFPA and AFPB was found. A residue of valine was identified at the C-germinal end of both alpha-fetoproteins. The analysis of the CNRr-cleavage products reveals slight differences between AFPS and AFPB. The slow moving alpha-fetoprotein could be further fractionated on RCAI-sepharose column in two components, AFPA1 and AFPA2 differing by their sialic acid content.
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1. Histones were isolated from gonads of the star-fish Asterias rubens and characterized by their amino acid composition and their electrophoretic migration. 2. Comparative studies with calf thymus homologous histones show the highly conservative structure of the histones H3 and H4, and the variability of the other histones namely H1 and H2B.
Microtubules were prepared by in vitro polymerization-depolymerization cycles, 1.0 M NaCl which totally depolymerizes was then added to the preparation. After removal of NaCl new arrangements of tubulin were observed at 4 degrees C: simple and double rings as well as fibrils. At 37 degrees these structures disappeared and tubulin polymerized into microtubules. The highly microtubules contain tubulin, tubulin associated proteins of 300,000 and 330,000 molecular weight, minor proteins of low molecular weight and proteins similar to the Tau factors. This raises a question of the role played by low molecular weight polypeptides. Are they products of proteolysis of rather factors of polymerisation?
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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.
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.
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.
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.
Half automated method for determining a L-leucinamide splitting enzymatic activity in human sera. In normal and pathological human sera, two distinct L-leucinamide splitting enzymatic activities have been demonstrated. One of them has an optimal activity at pH 9 (alcaline leucine amidase activity) and shows the most properties of a classic leucinaminopeptidase (E.C. 3.4.11.1). The other (neutral leucine amidase activity) has an optimal activity at pH : 7,5--7,8 and is not activated by Mg2+ ions. In the present work a semi-automated method permitting the determination of the "neutral leucine amidase activity" is presented. The mean of the reference values for normal human sera are established to 31,54 mUI/ml, and the upper normal limit is 48 mUI/ml. The neutral leucine amidase activity is studied in pathological sera comparatively with two other aminopeptidase activities : "alcaline leucine amidase activity", and "leucine-arylamidase". Our study shows that in pathological sera, the neutral leucine amidase activity" varies often without any correlation with those parameters.
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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.