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R Esnault

Publications and source records attributed to R Esnault.

6 recordsLinked to original sources
PubMed1992

Preliminary crystallographic study of peanut peroxidase.

The cationic isozyme of peroxidase isolated from suspension cultures of peanut cells is a heme-containing and calcium-dependent glycoprotein having four covalently attached oligosaccharide chains. Attempts were made to crystallize the glycoprotein for X-ray diffraction analysis, and these have met with some success. Crystals have now been grown that are suitable for a full three-dimensional structural analysis. The crystals are thin plates and we have shown them to be of the orthorhombic space group P2(1)2(1)2(1) with a = 48.1, b = 97.2, c = 146.2 A. The crystals diffract to beyond 2.8 A resolution, appear to be stable to lengthy X-ray exposure, and contain two molecules of 40,000 daltons each in the asymmetric unit.

Arachis↗
PubMed1990

Molecular cloning of complementary DNAs encoding two cationic peroxidases from cultivated peanut cells.

We have isolated, cloned, and characterized two cDNAs corresponding to the mRNAs for cationic peroxidases synthesized by cultured peanut cells. The first clone was obtained from a phage lambda gt11 library screened with antibodies directed against the major secreted isozyme. Its predicted amino acid sequence, deduced from the 1228-base-pair (bp) cDNA, revealed a 22-amino acid signal peptide and a 294-amino acid mature protein (Mr, 31,228). The second clone was isolated from a lambda gt10 library screened with oligonucleotides corresponding to the regions for acid/base catalysis and the fifth ligand of heme. This cDNA (1344 bp) encodes a protein (330 amino acids) with a mature peptide of 307 residues (Mr, 32,954). The two peanut peroxidases are 46% homologous. The estimated gene copy numbers of these peroxidases might be close to 1 or 2 per haploid genome. A comparison of the amino acid sequence of these peanut peroxidases with other known isozymes shows two already known regions of homology (the region for acid/base catalysis and the fifth ligand of heme). Moreover, some new characteristics appeared such as a glycosylation site identical in five of the seven isozymes, a putative antigenic determinant common to all the isozymes, and a region of the highest homology. A secondary structure prediction showed that it corresponds to a 16-amino acid helix linked to the next one by a long stretch of beta strands and coils and might represent a critical structural element.

Amino Acid Sequence↗
PubMed1978

Study on plant RNAases. Isolation and properties of several activities from Vicia faba root cells.

Vicia faba root cells contain several nucleolytic activities: phosphomonoesterase and phosphodiesterase (which however were not studied in details), one nuclease and four ribonucleases. These results were obtained by separating the extracted proteins into anionic and cationic species by chromatography on CM-cellulose at pH 5.5 and analysing each kind of proteins. Anionic species were subjected to chromatography on DEAE-cellulose which lead to isolation of one nuclease (A1) and two RNAases (A2, A3), the properties of which were studied. It was shown that the RNAases pH optima are near 6; A2 is more thermolabile than A3; both are endonucleases unable to attack double-stranded structure; studies with homopolymers, i.e. poly(A), poly(I), poly(C), poly(U), showed that their base specificities were analogous to that of already known plant RNAases. The cationic proteins, analysed with CM-cellulose, contain two RNAases (C1, C2). The pH optima were near 6 and 7, respectively; C1 is much more thermolabile than C2; both were endonucleases inactive on double-stranded structures. C1 and C2 hydrolysed poly(C) and poly(U) but not poly(A) and poly(U).

Cations↗
PubMed1975

Polyadenylated RNA from Vicia faba meristematic root cells. Localization and size estimation of the poly (A) segment.

After incubating root apices from two-day-old bean seedlings with [3H] adenine the RNA was extracted from whole cells or polysomes, and the poly (A) sequences were isolated by nuclease digestion followed by poly(U)-Sepharose chromatography. The alterations of the RNA molecules due to the various treatments were monitored by sucrose density gradients. It was found that sequential extraction first at pH 7.6 then at pH 9.0 did not result in a separation between RNA poor in poly(A) sequences and poly(A)-rich RNA. Furthermore chromatography analysis of hydrolysates from nuclease-resistant RNA extracted either at pH 7.6 or pH 9.0 revealed that AMP constituted nearly 95% of the bases and that the poly(A) sequences, about 200 bases, were located at the 3' terminus of the polyadenylated RNA. No size difference was found for the poly(A) segment between the pH-7.6-extracted RNA and that extracted at pH 9.0.

Centrifugation, Density Gradient↗