André Cassaigne

Laryngeal and oropharyngeal cancer, and alcohol dehydrogenase 3 and glutathione S-transferase M1 polymorphisms.

Abstract In this study the GSTμ phenotype and ADH genotype at the ADH3 locus were investigated in a group of 39 alcoholic men with upper respiratory/digestive tract cancer: 21 with oropharyngeal cancer and 18 with laryngeal cancer. The results are compared with those of a control group of 37 alcoholic men without alcohol-related medical complications. Of the control subjects, 48% were found to be GSTμ deficient [GSTμ(–)] and 19% carried the ADH31/ADH31 genotype. In the laryngeal cancer patients, a significantly elevated frequency of both the GSTμ(–) (78%) and ADH31/ADH31 genotype (56%) was observed, relative to the control group. On the basis of this result, the risk of laryngeal cancer associated with the GSTμ(–) and ADH31/ ADH31 genotypic combination within the population of alcoholics was estimated to be 12.9 with a 95% confidence interval of 1.8–92 (P < 0.01) relative to alcoholic individuals who have GSTμ [GSTμ(+)] and are not ADH31/ADH31. Thus, alcoholics who are GSTμ(–) and ADH31/ADH31 have at least an 80% greater risk of developing laryngeal cancer than alcoholics who are GSTμ(+) and who are not ADH31/ ADH31. In addition, the oropharyngeal cancer patients had excess frequencies of both GSTμ(–) (62%) and ADH31/ ADH31 (43%) relative to the control group, but these excess frequencies were not statistically significant. The GSTμ(–) and ADH31/ADH31 genotypic combination may be a constitutional risk factor for laryngeal cancer among alcoholics.

Phosphonoacetaldehyde hydrolase from Pseudomonas aeruginosa: purification properties and comparison with Bacillus cereus enzyme.

Phosphonoacetaldehyde hydrolase (2-oxoethylphosphonate phosphonohydrolase, EC 3.11.1.1) has been purified to electrophoretic homogeneity from cells of Pseudomonas aeruginosa A 237 grown in a culture medium containing 2-aminoethylphosphonate as both phosphorus and carbon sources. The native Mr has been estimated to be 62,000 +/- 2000, using a gel filtration column equilibrated with standard proteins. A subunit of Mr 30,000 +/- 1000 determined in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gives evidence of a homodimeric structure. The enzyme, which catalyzes the C-P bond cleavage of phosphonoacetaldehyde, has a Km value of 210 microM. It is moderately inhibited by methyl-, ethyl-, propyl- and butylphosphonic acids and activated by aminomethyl-, aminoethylphosphonic acids as well as by phosphonoformic, phosphonoacetic and phosphonopropionic acids. Inhibition by orthophosphite is a time-dependent process which exhibits first-order kinetics and is enhanced by the presence of acetaldehyde. Assays for phosphite removal by dilution or dialysis do not reverse the inhibition. Phosphonoacetaldehyde hydrolase inactivation by phosphite ion appears to be inconsistent with the concept of a Schiff base intermediate as proposed for Bacillus cereus enzyme.

Role of Alcohol Dehydrogenase Polymorphism in Ethanol Metabolism and Alcohol-Related Diseases

In alcohol toxicity, a lot of data point to genetic factors associated with environmental factors. These genetic factors can intervene at different levels : genetic variability in the distribution of polymorphic alcohol and aldehyde dehydrogenase isozymes (Bosron, et al., 1988) could play a role in determining individual difference in ethanol metabolism and toxicity. In the future, other polymorphisms in alcohol metabolism may be described. Polymorphism is also to be considered in detoxication and/or target organ metabolism (as collagen polymorphism in alcoholic cirrhosis)(Weiner, et al., 1988).

Étude cristallographique et vibrationnelle de complexes metalliques de l'acide aminométhylphosphonique

Abstract The crystalline structure of the complex between Zn(II) and aminomethylphosphonic acid [Zn(AMPh) 2 · 4H 2 O] is described. This complex crystallizes as an orthorhombic system (space group Pca2 1 , a = 10.001 ± 0.002, b = 12.140 ± 0.002, c = 10.281 ± 0.002 A; Z = 4). Zinc is tetrahedral and coordinated with 4 oxygen atoms of 4 phosphonic groups. The IR spectra of this complex and its N -deuterated derivative in the solid state are analysed in relation to its structure. By comparison, a vibrational study of two other complexes showed Mn(II) gives the same type of coordination as Zn(II), but Cu(II) binds with both phosphonic and amino groups.

Transport of inorganic phosphate inPseudomonas aeruginosa

Inorganic phosphate transport by wild-typePseudomonas aeruginosa cells grown in a phosphate-limited medium involves a biphasic process. The uptake obeys Michaelis-Menten kinetics with respective apparentKm values of 1.1 μM and 10 μM for the high- and low-affinity systems. These systems may be also differentiated by their sensitivity to osmotic shock, by their specificity towards phosphite, pyrophosphate, arsenate, and some phosphonates and also by their energy requirements. The two phosphate transport systems fromP. aeruginosa are compared with the two major systems (Pst and Pit) characterized inEscherichia coli.

Phosphoserine Aminotransferase, the Second Step‐Catalyzing Enzyme for Serine Biosynthesis

As a step toward analyzing the serine biosynthetic pathway in mammals, we have studied the properties of phosphoserine aminotransferase, the second step‐catalyzing enzyme. The Km values for 3‐phosphohydroxypyruvate and L‐phosphoserine are 5 and 35 mu M, respectively, and those for glutamate and alpha‐ketoglutarate are 1.2 and 0.8 mM, respectively. The product inhibition studies strengthened the support for a ping‐pong mechanism and allowed evaluation of Ki values for the four substrates. The equilibrium constant evaluated from the kinetic parameters is 40. Additionally, some physical properties relative to the bound coenzyme and the secondary structure were investigated. The results are consistent with a structural relationship between the Escherichia coli enzyme and the mammalian enzyme. The mammalian enzyme has specific kinetic parameters, the determination of which is a prerequisite to analyzing the serine biosynthetic pathway in mammals.

Identification of a new apolipoprotein E variant (E2 Arg142 → Leu) in type III hyperlipidemia

A new rare apolipoprotein E mutant was identified as we were investigating the apolipoprotein E genotype of patients with type III hyperlipidemia (HLP III). The unusual DNA restriction fragment length polymorphism profile and then the sequence analysis of a PCR amplified fragment of the probands apo E gene revealed a simple base substitution (G-->T) at nucleotide 3836. This mutation leads to the replacement of arginine by leucine at position 142 of the mature protein. The proband carried the mutant allele at the heterozygous status with an epsilon 3 allele. Subsequently, analysis of the probands fathers apo E gene showed that same mutated allele associated with an epsilon 2 allele. The two subjects presented a dysbetalipoproteinemia in which this new apo E variant could be implicated.

Transamination non enzymatique des acides aminés phosphoniques

Abstract The authors have performed a comparative study of the non-enzymic transamination of ten aminophosphonic acids and their carboxylic analogues with some carbonyl compounds (α-oxo acids, pyridoxal, pyridoxal phosphate). An unfavourable influence of the phosphonic group towards the yield of the transamination reaction is shown by chromatography. On the other hand, a great affinity of α-aminophosphonic acids for pyridoxal phosphate is demonstrated using spectrophotometric methods. These results will emphasize the influence of the acid function, besides other structural factors, in the transamination reaction of amino acids.

Inhibition ofd-alanyl-d-alanine ligase in different bacterial species by amino phosphonic acids

A comparative study was performed on the kinetic properties and the specificity ofd-alanyl-d-alanine ligases fromPseudomonas aeruginosa, Streptococcus faecalis, andStaphylococcus aureus, using some aminophosphonic acids and related compounds.dl-I-Aminoethylphosphonic acid was shown to be a competitive inhibitor of theP. aeruginosa andS. faecalis ligases; assuming ad-form stereospecificity, its activity was nearly equal to that ofd-cycloserine. 2-Aminoethylphosphonate was found to be a weak inhibitor of the ligases, in contrast to the carboxylic analog, β-alanine. γ-Aminobutyric acid and phosphoethanolamine also exhibited some inhibitory properties.

FIRST CHARACTERIZATION OF THE PHOSPHONOACETALDEHYDE HYDROLASE GENE OF PSEUDOMONAS AERUGINOSA

The phnX gene encoding the phosphonoacetaldehyde hydrolase (phosphonatase) from the Gram-negative bacterium Pseudomonas aeruginosa A237 has been cloned and its sequence determined. The open reading frame consists of 825 nucleotides specifying a protein of 275 amino acid residues corresponding to a predicted molecular weight of 29929. The deduced amino acid sequence of PhnX did not share significant amino acid sequence similarity with any other polypeptide. Expression of the phosphonoacetaldehyde hydrolase coding sequence in Escherichia coli under control of the E. coli tac promoter resulted in the production of enzymatically active protein with an affinity constant similar to that of the phosphonoacetaldehyde hydrolase purified from P. aeruginosa A237. This is the first nucleic sequence report of the phosphonoacetaldehyde hydrolase, an enzyme involved in the carbon-phosphorus bond cleavage.