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A Ballio

Publications and source records attributed to A Ballio.

At least 37 records · Page 2Linked to original sources
PubMed1991

Syringopeptins, new phytotoxic lipodepsipeptides of Pseudomonas syringae pv. syringae.

The primary structure of some new lipodepsipeptides named syringopeptins, produced by plant pathogenic strains of Pseudomonas syringae pv. syringae has been determined by a combination of chemical methods, 1H and 13C NMR spectroscopy and FAB mass spectrometry. Two syringomycin-producing strains afforded 3-hydroxydecanoyl-Dhb-Pro-Val-Val-Ala-Ala-Val-Val-Dhb-Ala-Val-Ala- Ala-Dhb-aThr-Ser-Ala-Dhb-Ala-Dab-Dab-Tyr, with Tyr acylating a Thr to form a macrolactone ring, and smaller amounts of the 3-hydroxydodecanoyl homologue. Evidence was obtained that a third syringomycin-producing strain and a syringotoxin-producing strain synthesize 3-hydroxydecanoyl-Dhb-Pro-Val-Ala-Ala-Val-Leu-Ala-Ala-Dhb-Val-Dhb- Ala-Val-Ala-Ala-Dhb-aThr-Ser-Ala-Val-Ala-Dab-Dab-Tyr, with Tyr and aThr forming again the macrolactone ring, and smaller amounts of the 3-hydroxydodecanoyl homologue.

Amino Acid Sequence↗
PubMed1991

Binding of the recombinant proteinase inhibitor eglin c, of the soybean Bowman-Birk proteinase inhibitor and of its chymotrypsin and trypsin inhibiting fragments to Leu-proteinase, the leucine specific serine proteinase from spinach (Spinacia oleracea L.) leaves: thermodynamic study.

The effect of pH and temperature on the apparent association equilibrium constant (Ka) for the binding of the recombinant proteinase inhibitor eglin c (eglin c), of the soybean Bowman-Birk proteinase inhibitor (BBI) and of its chymotrypsin and trypsin inhibiting fragments (F-C and F-T, respectively) to Leu-proteinase, the leucine specific serine proteinase from spinach (Spinacia oleracea L.) leaves, has been investigated. On lowering the pH from 9.5 to 4.5, values of Ka (at 21 degrees C) for complex formation decrease thus reflecting the acidic pK-shift of the hystidyl catalytic residue from approximately 6.9, in the free Leu-proteinase, to approximately 5.1, in the enzyme: inhibitor adducts. At pH 8.0, values of the apparent thermodynamic parameters for the proteinase:inhibitor complex formation are: Leu-proteinase:eglin c-Ka = 2.2 x 10(11) M-1, delta G degree = -64 kJ/mol, delta H degree = +5.9 kJ/mol, and delta S degree = +240 kJ/molK; Leu-proteinase:BBI-Ka = 3.2 x 10(10) M-1, delta G degree = -59 kJ/mol, delta H degree = +8.8 kJ/mol, and delta S degree = +230 J/molK; and Leu-proteinase:F-C-Ka = 1.1 x 10(6) M-1, delta G degree = -34 kJ/mol, delta H degree = +18 J/mol, and delta S degree = +180 J/molK (values of Ka, delta G degree and delta S degree were obtained at 21.0 degrees C; values of delta H degree were temperature-independent over the range explored, i.e. between 10.0 degrees C and 40.0 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

Chymotrypsin↗
PubMed1990

Structure of syringotoxin, a bioactive metabolite of Pseudomonas syringae pv. syringae.

The covalent structure of syringotoxin, a bioactive metabolite of Pseudomonas syringae pv. syringae isolates, pathogenic on various species of citrus trees, has been deduced from 1D and 2D 1H- and 13C-NMR spectra combined with extensive FAB-MS data and results of some chemical reactions. Similarly to syringomicins and syringostatins, produced by other plant pathogenic strains of P. syringae pv. syringae, syringotoxin is a lipodepsinonapeptide. Its peptide moiety corresponds to Ser-Dab-Gly-Hse-Orn-aThr-Dhb-(3-OH)Asp-(4-Cl)Thr with the terminal carboxy group closing a macrocyclic ring on the OH group of the N-terminal Ser, which in turn is N-acetylated by 3-hydroxytetradecanoic acid.

Amino Acid Sequence↗
PubMed1990

Fusicoccin: receptors and endogenous ligands.

The first event in the mode of action of the fungal phytotoxin fusicoccin is the binding to specific receptors located at the plasma membrane. They are very likely related to the presence of endogenous compounds able to compete with FC for binding to its receptors. Some biochemical properties of these proteins conform to criteria commonly used for receptors. A functional relationship between fusicoccin receptors and the plasma membrane H(+)-ATPase which is assumed to be the final physiological target of fusicoccin, has been recently suggested. New support in favour of this relationship has been sought by studying a model system prepared by insertion into liposomes of preparations from maize tissues of the two proteins. The model system is capable of H(+)-translocation on ATP addition and the translocation is markedly stimulated by fusicoccin. Thus, it represents a promising tool for the understanding of fusicoccin signal transduction at the molecular level, since it can assist in the detection and assay of the transduction chain components contained in the impure protein preparations.

Binding Sites↗
PubMed1989

The structure of syringomycins A1, E and G.

By a combination of 1D and 2D 1H- and 13C-NMR, FAB-MS, and chemical and enzymatic reactions carried out at the milligram level, it has been demonstrated that syringomycin E, the major phytotoxic antibiotic produced by Pseudomonas syringae pv. syringae, is a new lipodepsipeptide. Its amino acid sequence is Ser-Ser-Dab-Dab-Arg-Phe-Dhb-4(Cl)Thr-3(OH)Asp with the beta-carboxy group of the C-terminal residue closing a macrocyclic ring on the OH group of the N-terminal Ser, which in turn is N-acylated by 3-hydroxydodecanoic acid. Syringomycins A1 and G, two other metabolites of the same bacterium, differ from syringomycin E only in their fatty acid moieties corresponding, respectively, to 3-hydroxydecanoic and 3-hydroxytetradecanoic acid.

Amino Acid Sequence↗
PubMed1989

Properties of proteoliposomes containing fusicoccin receptors from maize.

We have recently described a fusicoccin (FC)-sensitive system reconstituted by inserting into liposomes FC-receptors and H(+)-ATPase-enriched preparations from maize tissues. While the proteoliposomes of maize H(+)-ATPase had been already investigated, those of FC-receptors required a careful characterization before use in the dual system. In particular, the influence of the phospholipid environment on time-course, reversibility, and pH-dependence of the FC-binding reaction has been studied by comparing these properties in microsome-bound, solubilized, and liposome-entrapped receptors. Similarities and differences between the results of this investigation and those previously obtained with FC-receptors from spinach leaves suggest that functionally similar binding proteins from monocot and dicot plants have distinct structural features.

Journal Article↗
PubMed1988

Functional reconstitution of a proton-translocating system responsive to fusicoccin.

Crude fusicoccin binding proteins and a partially purified plasma membrane H+-transporting ATPase (EC 3.6.1.34), both solubilized from maize tissues, were simultaneously inserted into liposomes by the freeze-thaw method. ATP-driven intravesicular acidification in the proteoliposomes, measured by the fluorescence quenching of the dye 9-amino-6-chloro-2-methoxyacridine, markedly increased upon addition of fusicoccin to the reconstituted system. This effect could not be observed when binding sites and ATPase preparations were separately reconstituted into the proteoliposomes, thus demonstrating that fusicoccin binding to its receptor is a prerequisite for ATPase stimulation.

Aminoacridines↗
PubMed1987

The pH dependence of pre-steady-state and steady-state kinetics for the papain-catalyzed hydrolysis of N-alpha-carbobenzoxyglycine p-nitrophenyl ester.

Pre-steady-state and steady-state kinetics of the papain (EC 3.4.22.2)-catalyzed hydrolysis of N-alpha-carbobenzoxyglycine p-nitrophenyl ester (ZGlyONp) have been determined between pH 3.0 and 9.5 (I = 0.1 M) at 21 +/- 0.5 degrees C. The results are consistent with the minimum three-step mechanism involving the acyl X enzyme intermediate E X P: (Formula: see text). The formation of the E X S complex may be regarded as a rapid pseudoequilibrium process; the minimum values for k+1 are 8.0 microM-1 s-1 (pH less than or equal to 3.5) and 0.40 microM-1 s-1 (pH greater than 6.0), and that for k-1 is 600 s-1 (pH independent). The pH profile of k+2/Ks (= kcat/Km; Ks = k-1/k+1) reflects the ionization of two groups with pK' values of 4.5 +/- 0.1 and 8.80 +/- 0.15 in the free enzyme. The pH dependence of k+2 and k+3 (measured only at pH values below neutrality) implicates one ionizing group in the acylation and deacylation step with pK'' values of 5.80 +/- 0.15 and 3.10 +/- 0.15, respectively. As expected from the pH dependences of k+2/Ks (= kcat/Km) and k+2, the value of Ks changes with pH from 7.5 X 10(1) microM (pH less than or equal to 3.5) to 1.5 X 10(3) microM (pH greater than 6.0). Values of k-2 and k-3 are close to zero over the whole pH range explored (3.0 to 9.5). The pH dependence of kinetic parameters indicates that at acid pH values (less than or equal to 3.5), the k+2 step is rate limiting in catalysis, whereas for pH values higher than 3.5, k+3 becomes rate limiting. The observed ionizations probably reflect the acid-base equilibria of residues involved in the catalytic diad of papain, His159-Cys25. Comparison with catalytic properties of ficins and bromelains suggests that the results reported here may be of general significance for cysteine proteinase catalyzed reactions.

Catalysis↗
PubMed1986

Purification and Characterization of Leu-Proteinase, the Leucine Specific Serine Proteinase from Spinach (Spinacia oleracea L.) Leaves.

The leucine specific serine proteinase present in the soluble fraction of leaves from Spinacia oleracea L. (called Leu-proteinase) has been purified by acetone precipitation and a combination of gel-filtration, ion exchange, and adsorption chromatography. This enzyme shows a molecular weight of 60,000 +/- 3,000 daltons, an isoelectric point of 4.8 +/- 0.1, and a relative electrophoretic mobility of 0.58 +/- 0.03. The Leu-proteinase catalyzed hydrolysis of p-nitroanilides of N-alpha-substituted(-l-)amino acids as well as of chromogenic macromolecular substrates has been investigated between pH 5 and 10 at 23 +/- 0.5 degrees C and I = 0.1 molar. The enzyme activity is characterized by a bell-shaped profile with an optimum pH value around 7.5, reflecting the acid-base equilibrium of groups with pK(a) values of 6.8 +/- 0.1 and 8.2 +/- 0.1 (possibly the histidyl residue present at the active site of the enzyme and the N-terminus group). Among the substrates considered, N-alpha-benzoyl-l-leucine p-nitroanilide shows the most favorable catalytic parameters and allows to determine an enzyme concentration as low as 1 x 10(-9) molar. In agreement with the enzyme specificity, only N-alpha-tosyl-l-leucine chloromethyl ketone, di-isopropyl fluorophosphate and phenylmethylsulfonyl fluoride, among compounds considered specific for serine enzymes, strongly inhibit the Leu-proteinase. Accordingly, the enzyme activity is insensitive to cations, chelating agents, sulfydryl group reagents, and activators.

Journal Article↗
PubMed1986

Esterolytic Properties of Leucine-Proteinase, the Leucine-Specific Serine Proteinase from Spinach (Spinacia oleracea L.) Leaves : A Steady-State and Pre-Steady-State Study.

Steady-state and pre-steady-state kinetics for the hydrolysis of p-nitrophenyl esters of N-alpha-carbobenzoxy(-l-)amino acids catalyzed by leucine-proteinase were determined between pH 5 and 10 (I = 0.1 molar) at 23 +/- 0.5 degrees C. For the substrates considered: (a) the acylation step is rate-limiting in catalysis; (b) the pH profiles of k(cat) and k(cat)/K(m) reflect the ionization of two groups with pK(a) values ranging between 6.5 and 6.9, and 8.1 and 8.3 (probably, the histidine residue involved in the catalytic triad and the N-terminus, respectively); and (c) values of K(m) are pH independent. Among the substrates examined, N-alpha-carbobenzoxy-l-leucine-p-nitrophenyl ester shows the most favorable catalytic parameters and allows to determine an enzyme concentration as low as 5 x 10(-10) molar at the optimum pH value (approximately 7.5).

Journal Article↗
PubMed1980

Heavy metals and organochlorine residues in marine animals and coastal sediments of the Tirrenean sea around Naples.

A survey of selected heavy metals (Cd, Pb, Hg) and organo-chlorine hydrocarbons (DDT and PCB compounds) concentrations in marine animals and of mercury, DDT and PCB in coastal sediments, began in 1973. The sampling was confined to the Bay of Naples, and to the coast along Santa Maria di Castellabate, a small village about 100 km south of Naples which has recently declared a marine park. The results of this investigation indicate that contamination by the above pollutants is low; the extent of contamination in the bay of Naples, compared to that of the marine park, shows that the level of heavy metals and organochlorine hydrocarbons in the benthic organisms is nearly the same within the two areas, whereas that of the sediments of the bay is significantly higher than in the park.

Animals↗
PubMed1979

A new cerebroside from Fusicoccum amygdali Del.

A homogeneous cerebroside was isolated from a strain of Fusicoccum amygdali Del., a fungus pathogenic to almond and peach. Chemical degradations, together with extensive application of nuclear magnetic resonance and mass spectrometry techniques, led to elucidation of its structure. This corresponds to N-2'-hydroxy-3'-trans-octadecenoyl-1-O-beta-D-glucosyl-9-methyl-cis-4,x-8-sphingadienine.

Cerebrosides↗