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Biomedical subjects

V Buonocore

Publications and source records attributed to V Buonocore.

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

Determination of the primary structure of an alpha-amylase inhibitor from wheat kernel by Edman degradation and fast atom bombardment mass spectrometry.

The primary structure of an alpha-amylase inhibitor (coded 0.39) from wheat kernel was determined by fast atom bombardment mass spectrometry and Edman degradation. The sequence is similar to an extent of 97% compared to the other major component of the monomeric isoinhibitor family coded 0.28. The differences consist of the substitution of a single residue and the deletion of two residues in inhibitor 0.39. Neither heterogeneity nor polymorphism were observed in the primary structures of the inhibitors.

Amino Acid Sequence↗
PubMed1987

Effect of liver enzyme inducers on metabolite excretion in rats treated with 1-nitropyrene.

Non-induced and phenobarbital (PB) or methylcholanthrene (MC) pretreated rats were injected with 1-nitropyrene (1-NP). Mutagenic activity of urine and feces samples were compared by the Salmonella/microsome assay. The highest, indirect-acting mutagenicity was associated with urines from MC-induced rats; HPLC analysis of organic extracts of urine samples showed that the differences in mutagenic response can be ascribed to different amounts of hydroxy derivatives of N-acetylaminopyrene excreted. Monohydroxy derivatives of 1-NP, being detected in the HPLC profiles of urine from PB-induced rats only, could be responsible of the higher direct-acting mutagenic activity of these samples as compared to urine from non-induced or MC-induced rats. The excretion rate of aminopyrene, the main metabolite of 1-NP identified in rat feces samples, was not affected by inducer pretreatment.

Animals↗
PubMed1986

Glucose dehydrogenase from the thermoacidophilic archaebacterium Sulfolobus solfataricus.

Glucose dehydrogenase has been purified to homogeneity from cell extracts of the extreme thermoacidophilic archaebacterium Sulfolobus solfataricus. The enzyme utilizes both NAD+ and NADP+ as coenzyme and catalyses the oxidation of several monosaccharides to the corresponding glyconic acid. Substrate specificity and oxidation rate depend on the coenzyme present; when NAD+ is used, the enzyme binds and oxidizes specifically sugars presenting equatorial orientation of hydroxy groups at C-2, C-3 and C-4. The Mr of the native enzyme is 124,000 and decreases to about 60,000 in the presence of 6 M-guanidinium chloride and to about 30,000 in the presence of 5% (w/v) SDS. The enzyme shows maximal activity at pH 9, 77 degrees C and 20 mM-Mg2+, -Mn2+ or -Ca2+ and is fairly stable in the presence of chaotropic agents and water-miscible organic solvents such as methanol or acetone.

Amino Acids↗
PubMed1986

Biochemical, nutritional and toxicological aspects of alpha-amylase inhibitors from plant foods.

This paper is a critical review of the available data on plant protein inhibitors active either on animal or endogenous plant alpha-amylases. The First Section is a review of available data on molecular properties of the purified inhibitors from cereals, legumes, colocasia and yam. The Second Section deals with properties of amylase-inhibitor complexes and parameters controlling the interaction between amylases and inhibitors. The Third Section discusses possible roles of these inhibitors in the plant, whereas Section Four focuses on nutritional and toxicological significance of amylase inhibitors for human beings and other mammals. Lastly Section Five examines some applications in medicine of alpha-amylase inhibitors from plants.

Amino Acid Sequence↗
PubMed1985

Evaluation of concentration procedures of mutagenic metabolites from urine of diesel particulate-treated rats.

Several concentration procedures of mutagenic metabolites contained in the urine of diesel particulate-treated rats were compared. Mutagenicity was monitored by the Salmonella/microsome assay. The procedures tested were: lyophilization; filtration on XAD-2, XAD-7 or Sephadex LH-20 matrices; ultrafiltration; and extraction with organic solvents. Urine extraction with dichloromethane (DCM) gave almost quantitative recovery of activity while leaving salts and other polar compounds in the aqueous phase, and is the method recommended.

Animals↗
PubMed1984

Glucose metabolism in the extreme thermoacidophilic archaebacterium Sulfolobus solfataricus.

Sulfolobus solfataricus is a thermophilic archaebacterium able to grow at 87 degrees C and pH 3.5 on glucose as sole carbon source. The organism metabolizes glucose by two main routes. The first route involves an ATP-dependent phosphorylation to give glucose 6-phosphate, which readily isomerizes to fructose 6-phosphate. In the second route, glucose is converted into gluconate by an NAD+-dependent dehydrogenation; gluconate is then dehydrated to 2-keto-3-deoxygluconate, which, in turn, is cleaved to pyruvate and glyceraldehyde. Each metabolic step has been tested in vitro at 70 degrees C on dialysed homogenates or partially purified fractions; minimal requirements of single enzymes have been evaluated. Identification of the intermediates is based on chromatographic, spectroscopic and/or synthetic evidence and on specific enzymic assays. The oxidative breakdown of glucose to pyruvate occurring in S. solfataricus differs from the Entner-Doudoroff pattern in that there is an absence of any phosphorylation step.

Adenosine Triphosphate↗
PubMed1984

Biological availability of mutagenic compounds adsorbed onto diesel exhaust particulate.

Diesel particles were collected from the exhaust of a VW Golf diesel car by electrostatic precipitation. The particulate and its DCM extract were highly mutagenic in the Salmonella/microsome test in the presence and absence of metabolic activation; the highest response was observed with TA98 and TA1538 tester strains. The biological availability of particulate-associated mutagenic compounds was demonstrated by administering powder to rats and assaying, in vitro, the urine excreted within 24 h after treatment. The highest activity was obtained with TA98 in the presence of metabolic activation. Typical dose-effect responses were evident in urine of animals treated by all the administration routes tested (i.p., s.c. and per os), both in the presence and absence of a suspending vehicle. Concentration of mutagenic compounds present in urine of treated animals could be achieved by chromatography on Amberlite XAD-2 and XAD-7 resins. This study provides direct evidence for bioavailability to animal tissues of mutagens adsorbed onto diesel particulate, although part of the activity might be ascribed to nitroaromatic compounds formed during the collection of the powder. The present study is part of a more comprehensive work on diesel exhaust particulate, and results have to be considered in this light before any final conclusion can be drawn.

Adsorption↗
PubMed1980

Interaction of wheat monomeric and dimeric protein inhibitors with alpha-amylase from yellow mealworm (Tenebrio molitor L. larva).

The highly purified alpha-amylase from Tenebrio molitor L. larva (yellow mealworm) reversibly combines with two closely related homogeneous glycoprotein inhibitors, one dimeric (termed 'inhibitor 0.19') and one monomeric (termed 'inhibitor 0.28'), from wheat flour. As established by means of difference spectroscopy and kinetic studies, molar combining ratios for the amylase--inhibitor-0.19 and amylase-inhibitor-0.28 complexes were 1:1 and 1:2 respectively. Two amylase--inhibitor-0.19 complexes with slightly different retention volumes on Bio-Gel P-300 and only one amylase--inhibitor-0.28 complex were observed. Dissociation constants of the amylase--inhibitor-0.19 and amylase--inhibitor-0.28 complexes were 0.85 nM and 0.13 nM respectively. A strong tendency of both complexes to precipitate under an ultracentrifugal field was observed; the minimum molecular weight calculated for the two complexes under such conditions was approx. 95 000. The two complexes showed difference spectra indicating involvement of structurally related or identical tryptophyl side chains in the binding of inhibitors 0.28 and 0.19 to the amylase. A model summarizing the main features of the inhibition of the insect amylase by the two wheat protein inhibitors is proposed.

Animals↗
PubMed1977

Purification and properties of alpha-amylase from chicken (Gallus gallus L.) pancreas.

Amylase from chicken pancreas was purified by an affinity method involving filtering a crude extract from pancreas through a Sepharose-wheat albumin column and eluting the retained enzyme with maltose. The purified amylase showed two active bands upon polyacrylamide electrophoresis in an alkaline buffer system and only one band in an acidic buffer system. The enzyme is a Ca2+-glycoprotein which behaves as a typical alpha-amylase. It consists of a single polypeptide chain with molecular weight 53,000 and contains 5.3 moles of reducing sugars per mole of protein. Optimal conditions of pH and temperature for the enzymic activity are 7.5 and 37 degrees C. The enzyme is irreversibly inactivated by removal of Ca2+ by exhaustive dialysis and is activated by the presence in the assay mixture of Cl-; other halides are less effective than Cl- in activating the enzyme.

Amylases↗
PubMed1976

Physical and catalytic properties of alpha-amylase from Tenebrio molitor L. larvae.

The amylase from Tenebrio molitor L. larvae (yellow mealworm) was characterized according to a number of its molecular and catalytic properties. The insect amylase is a single polypeptide chain with mol.wt. 68000, an isoelectric point of 4.0 and a very low content of sulphur-containing amino acids. The enzyme is a Ca2+-protein and behaves as an alpha-amylase. Removal of Ca2+ by exhaustive dialysis against water causes the irreversible inactivation of the enzyme. Moreover, the enzyme is activated by the presence in the assay mixture of Cl-, or some other inorganic anions that are less effective than Cl-, and is inhibited by F-. Optimal conditions of pH and temperature for the enzymic activity are 5.8 and 37 degrees C. The insect amylase exhibits an identical kinetic behaviour toward starch, amylose and amylopectin; the enzyme hydrolyses glycogen with a higher affinity constant. Compared with the non-insect alpha-amylases described in the literature, Tenebrio molitor amylase has a lower affinity for starch.

Amylases↗
PubMed1976

Stable, inducible thermoacidophilic alpha-amylase from Bacillus acidocaldarius.

Bacillus acidocaldarius Agnano 101 produces an inducible thermoacidophilic alpha-amylase. The enzyme production occurs during the stationary phase of growth in the presence of compounds with alpha-1,4-glucosidic linkages. The enzymatic activity is both present in the culture medium and associated with the cells; the enzymes purified from both sources show identical molecular and catalytic properties. The purified amylase has a single polypeptide chain of molecular weight 68,000 and behaves like an alpha-amylase with affinity constants for starch and related substances of 0.8 to 0.9 mg/ml. The pH and temperature optima for activity are 3.5 and 75degreesC, respectively. The amylase is stable at acidic pH (below 4.5). Its thermal stability is strictly dependent upon protein concentration; the half-life at 60degreesC of the amylase in a 70-mug/ml solution is about 5 days.

Amylases↗
PubMed1975

Affinity column purification of amylases on protein inhibitors from wheat kernel.

An affinity column was devised for the purification of a large number of amylases inhibited by the albumin from wheat kernel. The procedure involved linking the protein inhibitors from wheat to Sepharose and then specifically eluting the amylase adsorbed to the gel with a high concentration of maltose. By this procedure, the amylases from Tenebrio molitor L. (yellow mealworm) larvae and chicken pancreas were purified to homogeneity with good yields for the first time, as shown by both alkaline and acidic electrophoresis. Human saliva alpha-amylase, purified by the same procedure, showed specific activity and electrophoretic patterns similar to those obtained by other workers with different techniques.

Adsorption↗