ABSTRACT
BACKGROUND: Acetylation alters several protein properties including molecular weight, stability, enzymatic activity, protein-protein interactions, and other biological functions. Our previous findings demonstrating that diacetyl/peroxynitrite can acetylate L-lysine, L-histidine, and albumin in vitro led us to investigate whether diacetyl-treated rats suffer protein acetylation as well. METHODS: Wistar rats were administered diacetyl daily for four weeks, after which they were sacrificed, and their lung proteins were extracted to be analysed by Nano-LC-MS/MS (Q-TOF). A C18 reversed-phase column and gradient elution with formic acid/acetonitrile solutions from 2 to 50% over 150 min were used to separate the proteins. Protein detection was performed using a microTOF-Q II (QTOF) equipped with captive source and an electrospray-ionization source. The data from mass spectrometry were processed using a Compass 1.7 and analyzed using Protein Scape, software that uses Mascot algorithms to perform protein searches. RESULTS: A set of 3,162 acetylated peptides derived from 351 acetylated proteins in the diacetyl-treated group was identified. Among them, 23 targeted proteins were significantly more acetylated in the diacetyl-treated group than in the PBS control. Protein acetylation of the group treated with 540 mg/kg/day of diacetyl was corroborated by Western blotting analysis. CONCLUSIONS: These data support our hypothesis that diacetyl exposure in animals may lead to the generation of acetyl radicals, compounds that attach to proteins, affecting their functions and triggering adverse health problems.
ABSTRACT
Alicyclobacillus acidoterrestris is a spoilage-causing bacterium in fruit juices. The inactivation of this bacterium by commercial saponin and saponin purified extract from Sapindus saponaria fruits combined with heat-treatment is described. We investigated heat treatment (87, 90, 95, and 99°C) with incubation time ranging from 0 to 50min, in both concentrated and reconstituted juice. Juices were inoculated with 1.0×10(4)CFU/mL of A. acidoterrestris spores for the evaluation of the best temperature for inactivation. For the temperatures of 87, 90, and 95°C counts of cell viability decreased rapidly within the first 10 to 20min of incubation in both concentrated and reconstituted juices; inactivation at 99°C ensued within 1 and 2min. Combination of commercial saponin (100mg/L) with a very short incubation time (1min) at 99°C showed a reduction of 2.34 log cycle for concentrated juice A. acidoterrestris spores (1.0×10(4)CFU/mL) in the first 24h of incubation after treatments. The most efficient treatment was reached with 300, 400 or 500mg/L of purified extract of saponins from S. saponaria after 5days of incubation in concentrated juice, and after 5days with 300 and 400mg/L or 72h with 500mg/L in reconstituted juice. Commercial saponin and purified extracts from S. saponaria had similar inactivation power on A. acidoterrestris spores, without significant differences (P>0.05). Therefore, purified extract of saponins can be an alternative for the control of A. acidoterrestris in fruit juices.
