A small cadmium resistance plasmid isolated from Staphylococcus aureus

We have isolated from Staphylococcus aureus a plasmid named pIP983, which measures 3.2 kb and specifies resistance to cadmium. The cad gene it carries is of the B type, as indicated by the level of resistance it confers on S. aureus and the sequence homology with the known cadB gene. Sequences homologous to pIP983 were found on several large S. aureus plasmids. They were localized close to the mcr region of pI/258 and pII147, and, at least in the case of the latter plasmid, were not contiguous, but interrupted by nonhomologous DNA.     

Studies on aroyl- and aryl-hydrazide derivatives from d-glycero-d-gulo-heptono-1,4-lactone

A series of aroyl- and aryl-hydrazide derivatives was prepared from d-glycero-d-gulo-heptono-1,4-lactone (1). The reactivity of the NH proton in these hydrazides, in terms of their dissociation constants (pK_a), was determined from their electronic spectra, and correlated to the Hammett σ values of the substituents. Comparable reactivities of the NH protons for the compounds, and the effect of the substituent, were studied by n.m.r. spectroscopy. Decomposition of the aroylhydrazides with copper(II) sulfate or nitrous acid resulted in the regeneration of 1.     

Myeloperoxidase-catalyzed inactivation of alpha 1-protease inhibitor by human neutrophils

We have examined the effect of the myeloperoxidase-hydrogen peroxide-halide system and of activated human neutrophils on the ability of serum alpha 1-protease inhibitor (alpha 1-PI) to bind and inhibit porcine pancreatic elastase. Exposure to the isolated myeloperoxidase system resulted in nearly complete inactivation of alpha 1-PI. Inactivation was rapid (10 to 20 s); required active myeloperoxidase, micromolar concentrations of H2O2 (or glucose oxidase as a peroxide generator), and a halide cofactor (Cl- or I-); and was blocked by azide, cyanide, and catalase. Intact neutrophils similarly inactivated alpha 1-PI over the course of 5 to 10 min. Inactivation required the neutrophils, a halide (Cl-), and a phorbol ester to activate secretory and metabolic activity. It was inhibited by azide, cyanide, and catalase, but not by superoxide dismutase. Neutrophils with absent myeloperoxidase or impaired oxidative metabolism (chronic granulomatous disease) failed to inactivate alpha 1-PI, and these defects were specifically corrected by the addition of myeloperoxidase or H2O2, respectively. Thus, stimulated neutrophils secrete myeloperoxidase and H2O2 which combine with a halide to inactivate alpha 1-PI. We suggest that leukocyte-derived oxidants, especially the myeloperoxidase system, may contribute to proteolytic tissue injury, for example in elastase-induced pulmonary emphysema, by oxidative inactivation of protective antiproteases.     

Phosphorylation of a nonhistone protein fraction which coextracts with the high-mobility-group proteins of chromatin

³²P-labelled chromatin proteins from rat liver and ventral prostate were fractionated according to the procedure designed to enrich high-mobility-group (HMG) nonhistone proteins. This fraction, however, reproducibly demonstrated small amounts of apparently basic nonhistone proteins other than HMG nonhistone proteins. These proteins appeared to be tissue specific and were highly labelled with ³²P. The ³²P-labelled phosphoproteins were soluble in trichloroacetic or perchloric acid, migrated in acid-urea polyacrylamide gels, and demonstrated pI values ranging from 6.8 to 7.5. The HMG proteins 1 and 2 showed no incorporation of radioactivity under these experimental conditions.     

Synthesis of daunosamine-containing disaccharides

Treatment of 2,3,6-trideoxy-1,4-di-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-l-lyxo-hexopyranose (1) with benzyl 2,3-dideoxy-d-glycero-pentopyranoside and p-toluenesulfonic acid gave a mixture of benzyl 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3- (trifluoroacetamido)-l-lyxo-hexopyranoside (49%) and benzyl 2,3-dideoxy-4-O-[2,3,6-trideoxy-4-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-α-l-lyxo-hexopyranosyl]-d-glycero-pentopyranoside (4, 20 %). The structure of the disaccharide 4 was confirmed by a detailed, mass-spectrometric analysis in three modes, namely, negative- and positive-ion, chemical ionization, and electron impact. Similar treatment of the bis(p-nitrobenzoate) 1 with ethyl 2,3-dideoxy-d-glycero-pentopyranoside gave the ethyl glycoside and the desired disaccharide, showing that the transglycosylation is not restricted to benzyl glycosides. Removal of the p-nitrobenzoyl and the benzyl groups from 4 gave the disaccharide 2,3-dideoxy-4-O-(2,3,6-trideoxy-3-trifluoroacetamido-α-l-lyxo-hexopyranosyl)-d-glycero-pentopyranose.     

Synthesis of 7-(tetrahydropyran-2-yl)- and 7-(4-acetoxytetrahydropyran-2-yl)-ε-rhodomycinone and 7-(tetrahydropyran-2-yl)-ε-pyrromycinone

The ¹³C.n.m.r spectra of water-soluble and -insoluble glucans synthesized by enzymes isolated from six strains of Streptococcus mutans are interpreted. The glucans are shown to be composed primarily of α(1→3)- and α-(1→6)-linked glucosyl residues, and the relative abundance of each linkage is estimated from peak areas. Treatment of water-insoluble glucans with dextranase is found to result in water-soluble and -insoluble products, the former enriched in α-(1→6)-linkages and the latter in α-(1→3)-linkages. The structural conclusions arrived at by ¹³C-n.m.r. spectroscopy are consistent with data from methylation analysis and ¹H-n.m.r. spectroscopy.     

The reduction of aldehydes by broad bean and maize alcohol dehydrogenases and a study of the substrate binding to the enzyme protein

Alcohol dehydrogenase was prepared from 2-day germinating maize and 3-day germinating broad-bean seeds by ammonium sulphate fractionation of sodium phosphate extracts, chromatography onDEAE cellulose and Sephadex G-200. The activity of the broad beanADH amounted to182 800 units per mg protein, that of maizeADH 79 000 units per mg protein. Besides oxidation of a series of alcohols at pH optimum in the alkaline region and with KM equalling 10-2M, alcohol dehydrogenases isolated from both plants catalyze the reduction of acetaldehyde, n-propanal, n-butanal, isobutanal and crotonal at pH optimum in the neutral region with KM equalling 10-3M. The inhibition studies using fatty acids and chloride ions revealed that the oxidation of alcohols is inhibited competitively by both types of inhibitors, with inhibition constants of 10-2M and 10-1M, respectively. The inhibition in the presence of acetaldehyde is non-competitive since the inhibitors do not compete with acetaldehyde and do not form an enzyme-NADH-inhibitor complex, yet they obviously react with the enzyme-NAD product only, thus giving rise to an enzyme-NAD-inhibitor complex. These differences in the behaviour of inhibitors may be interpreted in the sense that the binding sites of ethanol and acetaldehyde as substrates for broad bean and maize alcohol dehydrogenases are non equivalent. The nonequivalency discussed in the text.     

Reactions of 3-(1-arylhydrazono-L-threo-2,3,4-trihydroxybutyl)-1-methyl-2-Quinoxalinones

The 1-methyl derivatives (3 and 4) of 3-(1-phenyl- (1) and 3-(1-p-bromophenylhydrazono-L-threo-2,3,4-trihydroxybutyl)-2-quinoxalinone (2) were prepared by methylation. Periodate oxidation of 3 gave 1-methyl-3-[1-(phenylhydrazono)glyoxal-1-yl]-2-quinoxalinone (5), which, on reduction with sodium borohydride, gave the corresponding 3-[2-hydroxy-1-(phenylhydrazono)ethyl] derivative (8). Reaction of 5 with hydroxylamine or benzoylhydrazine gave the corresponding 2-oxime (6) and 2-(benzoylhydrazone) (7), respectively. Acetic anhydride causes one molecule of 3 or 4 to undergo elimination of two molecules of water, with simultaneous acetylation and ring closure to afford pyrazoles 9 and 10, respectively. Pyrolysis of the triacetate of 3 led to the elimination of acetic acid from the sugar and the hydrazone residue, to give the 3-[5-(acetoxymethyl)-1-phenylpyrazol-3-yl] derivatives (9). Acetic acid was found to effect the same rearrangement, but without acetylation, of 1, 2, and 3 to give the 3-[5-(hydroxymethyl)] derivatives 11, 12, and 13, respectively. The structure of these pyrazoles was confirmed by a series of reactions, including methylation and acetylation. The n.m.r. and i.r. spectra of the compounds were investigated.     

Release of chemical mediators from partially purified human lung mast cells.

Human lung mast cells dispersed by enzymatic digestion of human lung fragments were concentrated to greater than 50% purity by sedimentation in isopycnic and velocity gradients. The dispersed lung mast cells had a characteristic ultrasturctural appearance including granules with a scroll or reticular structural appearance including granules with a scroll or reticular structure surrounded by perigranular membranes. Histamine and preformed eosinophilotactic activity sedimented with mast cells on isopycnic gradients, and mast cells and these mediators were separated from the bulk of the other lung cells after velocity gradient sedimentation. The histamine content of isolated lung mast cells was calculated to range from 1.0 to 5.5 pg/cell. The quantity of SRS-A generated with anti-IgE or specific antigen was relatively limited but confined to the mast cell-rich fractions and associated with release of histamine and eosinophilotactic activity.