The Brucella ovis dnaK gene, homolog to the eukaryotic hsp70 genes, was cloned by using a Drosophila melanogaster probe

A new Candida parapsilosis lipase was isolated and studied. This enzyme was purified by hydrophobic chromatography on a phenyl-sepharose CIAB column followed by gel permeation on a Sephacryl $300 HR column. It was a 160 kg'mo1-1 molecular-weight oligomeric enzyme. Optimal activity was obtained at 45°C and pH 6.5. The lipase activity toward various acylglycerols and esters was studied. The hydrolysis rate was greater for secondary acylesters than for primary acylesters. This lipase showed a high specificity for long-chain fatty acids and particularly for polyunsaturated fatty acids. This enzyme was able to catalyze the synthesis of various oleoylesters in aqueous medium.

Jacalin is a plant lectin known to specifically induce the proliferation of CD4+ T lymphocytes in human. We demonstrate here that jacalin completely blocks human immunodeficiency virus type 1 (HIV-1) in vitro infection of lymphoid cells. Jacalin does not bind the viral envelope glycoprotein gp120. Besides other T cell surface molecules, it interacts with CD4, the high-affinity receptor to HIV. Binding of jacalin to CD4 does not prevent gp120-CD4 interaction and does not inhibit virus binding and syncytia formation. The anti-HIV effect of the native lectin can be reproduced by its separated alpha-subunits. More importantly, we have defined in the alpha-chain of jacalin a 14-amino acid sequence which shows high similarities with a peptide of the second conserved domain of gp120. A synthetic peptide corresponding to this similar stretch also exerts a potent anti-HIV effect. This peptide is not mitogenic for peripheral blood mononuclear cells and does not inhibit anti-CD3-induced lymphocyte proliferation. These results make jacalin alpha chain-derived peptide a potentially valuable therapeutic agent for acquired immunodeficiency syndrome.

An amidase with a wide activity spectrum was purified from the Brevibacterium sp. R 312 and studied. The purification was performed by precipitating the proteins of the supernatant fraction obtained after centrifugation of sonicated cells. The resulting proteins were submitted to a gel filtration step followed by DEAE-Sephadex ion exchange chromatography and then by another gel filtration process. The purified amidase had a molecular weight of 180,000 and was composed of four subunits of the same molecular weight (43,000 2,000). Its isoelectric point was 3.5. This enzyme was able to hydrolyze a large number of amides into their corresponding organic acids and it also possessed an acyl transferase activity.Amidases, and especially microbial amidases, have been extensively studied (CLARKE 1970). These enzymes seem t o be very wide spread among protists: bacteria (CLARKB The Brevibacterium sp. R 312 strain is able to transform all sufficiently water-soluble iiitriles into the corresponding organic acids with their amides as an intermediary step (ARNAUD et al. 1976 a, b and c).Two mutant strains were isolated from the Brevibacterium sp. R 312 wild type strain:Brevibacterium sp. 19 is no longer able to hydrate nitriles into amides; it retains, however, an amidase activity similar to the wild type (BUI et al. 1984a); Brevibacterium sp. A4 has a nitrile-hydratase activity identical to that of the R 312 strain, but does no longer hydrolyze most amides into corresponding organic acids ( JALLAGEAS et al. . The isolation of these two mutant strains conclusively demonstrated that two wide spectrum enzymes are involved in the metabolism of nitriles by the Brevibacterium sp. R 312 strain:-a nitrile-hydratase which transforms nitriles into amides.-an amidase which hydrolyzes amides into their corresponding organic acids.Besides the Brevibacteriurn sp. R 312, Arthrobacter sp. J-1 (YAMADA et al. , ASANO et al. 1980, 1982a was reported recently as one of the very few microorganisms possessing both kinds of enzymes. 20'