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Biomedical subjects

B Picard

Publications and source records attributed to B Picard.

At least 145 records · Page 8Linked to original sources
PubMed1983

[Characterization of Escherichia coli esterase B after separation by chromatography].

Esterase B of Escherichia coli has been purified 56 fold with recovery of 39%. The apparent molecular weight as determined by gel filtration was approximately 57000. The pI as determined by isoelectric focusing was 4.6. This enzyme exhibited Michaelis-Menton kinetics with apparent Km of 0.25 mM for l-naphtyl acetate. It remained stable at 60 degrees C but was sensitive to pH values below 6. The esterase activity was completely inhibited by Di-isopropyl-fluorophosphate (DFP) but was resistant to iodoacetamide and to EDTA.

Carboxylic Ester Hydrolases↗
PubMed1980

Purification and characterization of Treponema hyodysenteriae hemolysin.

A hemolysin produced by Treponema hyodysenteriae ATCC27164 was purified from broth filtrates by acetic and (NH4)2SO4 precipitations followed by ion exchange chromatography on diethylaminoethyl-Sephacel and gel filtration using Ultrogel AcA44. The purified hemolysin displayed only one band on polyacrylamide gel electrophoresis. By gel filtration the molecular weight was estimated as 74,000 daltons. The isolated hemolysin was oxygen resistant, heat labile and was not inactivated over a wide range of pH values. Further analysis indicated that this hemolysin was probably a polypeptide or a protein associated with lipids and nucleotides. Its action on rabbit erythrocytes which did not require any divalent cations could not be related to a lipolytic or proteolytic activity.

Animals↗
PubMed1980

Biochemical Research on oogenesis. Composition of the 42-S storage particles of Xenopus laevix oocytes.

Previtellogenic oocytes of Xenopus laevis contain far more 5-S RNA and tRNA than 28-S + 18-S RNA. tRNA and 5-S RNA are storage products that will be used in later oogenesis for protein synthesis and ribosome assembly. Stored tRNA and 5-S RNA are not free in the cell sap but belong to nucleoprotein particles of various sizes. There are two prominent kinds of storage particles in previtellogenic oocytes of X. laevis. The smaller ones (7-S) contain about half of the cell's 5-S RNA. The larger ones (42-S) contain the remainder of the 5-S RNA and 90% of the tRNA. The 7-S particles consist of one molecule of 5-S RNA and one molecule of protein. In this paper we describe the biochemical and physical properties of the 42-S particles. The 42-S particle contains four main components: tRNA, 5-S RNA, a 50000-Mr protein (a) and a 40000-Mr protein (b) in the following molar ratios: 3/1/2/1. We propose a 28-component model for the 42-S particles. This model is consistent with all the biochemical and physical data that we report here. A 42-S particle is made up of four subunits, each of which contains three molecules of tRNA, one molecule of 5-S RNA, two molecules of protein a, and one molecule of protein b. Protein b from the 42-S particles and the 7-S particle protein are indistinguishable by all tests that we have tried. We present evidence showing that protein a binds tRNA whereas protein b binds 5-S RNA in the 42-S particles as well as in the 7-S particles.

Animals↗
PubMed1980

[Comparative study of the biochemical characteristics of hemolytic treponemes isolated from pigs].

A number of hemolytic strains of treponemes were isolated from normal pigs and pigs which died of swine dysentery. According to their hemolytic pattern, these strains can be differentiated into strongly beta-hemolytic and weakly beta-hemolytic. According to Kinyon and Harris, aside from enteropathogenicity and hemolytic pattern, both fructose fermentation and indole production are the characteristics used in separating the two groups of treponemes. Our comparative study of these two groups of strains shows that while the fermentation activity is low for the strongly beta-hemolytic strains it is high for the weakly beta-hemolytic strains. The latter constitutes a heterogenous group which, contrary to Kinyon and Harris, can only be differentiated from the other strains by their ability to ferment lactose and to produce isovaleric acid in glucose supplemented broth.

Amino Acids↗
PubMed1979

Isolation of a 7S particle from Xenopus laevis oocytes: a 5S RNA-protein complex.

Previtellogenic oocytes of Xenopus laevis contain a free 5S RNA-protein complex sedimentating at 7 S. This particle consists of one molecule of 5S RNA and one 45,000-dalton protein. The protein of the 7S particle and the protein that is released in association with 5S RNA when the ribosome is treated with EDTA are unrelated. Because the 5S RNA accumulated by small oocytes in storage particles is incorporated into the ribosome later in oogenesis, we conclude that 5S RNA is succesively associated with two proteins during the life span of the oocyte.

Amino Acids↗
PubMed1979

[Dermatophilus congolensis infection in a dairy cow in Quebec (author's transl)].

Dermatophilus congolensis infection in a dairy cow in QuebecA case of infection by Dermatophilus congonlensis is described for the first time in the Province of Quebec, in a dairy cow. Dermatophilosis was diagnosed in the area of Saint-Hyacinthe in October 1978. It was not possible to find the source of the infection. The isolation of the microorganism was successful and the three techniques used are described. The death of the animal was attributed to complications following invasion by a secondary pathogen. All the other animals in the herd were free from clinical signs of infection. Moreover, no other case of infection by D. congolensis was found in other animal species or humans in the area.

Actinomycetales↗
PubMed1978

[Effect of fatty acids on the antibacterial activity of butylated hydroxytoluene (BHT)].

This study deals with the effect of the association of certain fatty acids with butylhydroxytoluene (BHT) on the antibacterial activity of this antioxidant. Evidence is drawn from the results as to an increase of the inhibitory effect of the antioxidant towards a few bacterial strains when it is associated with either lauric acid or palmitoleic acid.

Antioxidants↗
PubMed1976

Torpedo marmorata acetylcholinesterase; a comparison with the Electrophorus electricus enzyme. Molecular forms, subunits, electron microscopy, immunological relationship.

Electron microscopy, sequential degradation by hydrolytic enzymes and the physical-chemical properties of the molecular forms of Torpedo acetylcholinesterase indicate that these molecules are structurally related to each other in the same way as the molecular forms of Electrophorus acetylcholinesterase: all are derived from a complex structure in which three tetrameric groups of subunits are associated with a rod-like 'tail'. In aged preparations the catalytic subunits are split into fragments in a manner similar to those of Electrophorus acetylcholinesterase. Immunological cross-reaction between both enzymes demonstrates the occurrence of common antigenic sites. The enzymes from the two sources, however, are different in their molecular weights and susceptibility to hydrolytic enzymes. Also, Torpedo acetylcholinesterase does not precipitate with either isologous or heterologous antibodies.

Acetylcholinesterase↗
PubMedDate not supplied

An evaluation of allozyme amino acid substitutions for the study of molecular relationships in Providencia strains.

Through analysis of molecular relationships in terms of amino acid substitutions, intra- and interspecies differentiations in Providencia alcalifaciens, P. stuartii and P. rustigianii were evaluated among the electrophoretic variants of three enzymes, L-malate dehydrogenase, acid phosphatase and esterase-beta a, chosen for their distinct pattern of polymorphism. For each enzyme, molecular relatedness among variants defined by two-dimensional electrophoretic profiles was examined through protein titration curves. P. stuartii strains appeared identical to each other and P. rustigianii strains were closely related, whereas the division of P. alcalifaciens strains into previously described zymotypes A1 and A2 was refined in molecular terms. A gradient of molecular interrelatedness between the species was observed for the three enzyme loci: with L-malate dehydrogenase, the three species appeared very closely related; with acid phosphatase, P. stuartii and P. alcalifaciens were more closely related to each other than to P. rustigianii; with esterase-beta a, P. alcalifaciens and P. stuartii appeared partially related, whereas no such relatedness was observed between these two species and P. rustigianii.

Acid Phosphatase↗