Time scale of glycation in collagen of bovine pericardium-derived bio-tissues

Glycosylation is the process of combining one or more glucose molecules (or other monosaccharides) with molecules of a different nature (which are therefore glycosylated). In biochemistry, glycosylation is catalyzed by several specific enzymes, and assumes considerable importance since it occurs mainly at the expense of proteins and phospholipids which are thus transformed into glycoproteins and glycolipids. Conversely, in diabetes and aging, glycation of proteins is a phenomenon of non-enzymatic nature and thus not easily controlled. Glycation of collagen distorts its structure, renders the extracellular matrix stiff and brittle and at the same time lowers the degradation susceptibility thereby preventing renewal. Based on models detailed in this paper and with parameters determined from experimental data, we describe the glycation of type 1 collagen in bovine pericardium derived bio-tissues, upon incubation in glucose and ribose. With arginine and lysine/hydroxylysine amino acids as the primary sites of glycation and assuming that the topological polar surface area of the sugar molecules determines the glycation rates, we modelled the glycation as a function of time and determined the glycation rate and thus the progression of glycation as well as the resulting volume increase.

Fast enzymatic HCO3- dehydration supports photosynthetic water oxidation in Photosystem II from pea

Carbonic anhydrase (CA) activity, associated with Photosystem II (PSII) from Pisum sativum, has been shown to enhance water oxidation. But, the nature of the CA activity, its origin and role in photochemistry has been under debate, since the rates of CA reactions, measured earlier, were less than the rates of photochemical reactions. Here, we demonstrate high CA activity in PSII from Pisum sativum, measured by HCO3- dehydration at pH 6.5 (i.e. under optimal condition for PSII photochemistry), with kinetic parameters Km of 2.7 mM; Vmax of 2.74·10-2 mM·sec-1; kcat of 1.16·103 sec-1 and kcat/Km of 4.1·105 M-1 sec-1, showing the enzymatic nature of this activity, which kcat exceeds by ~13 times the rate of PSII, as measured by O2 evolution. The similar dependence of HCO3- dehydration, of the maximal quantum yield of photochemical reactions and of O2 evolution on the ratio of chlorophyll/photochemical reaction center II demonstrate the interconnection of these processes on the electron donor side of PSII. Since the removal of protons is critical for fast water oxidation, and since HCO3- dehydration consumes a proton, we suggest that CA activity, catalyzing very fast removal of protons, supports efficient water oxidation in PSII and, thus, photosynthesis in general.

Mycotoxin degradation by microbial metabolites

Extracellular metabolites of Gliocladium roseum GRZ7 are able to destroy aflatoxin B1 and zearalenone (by 61.9 and 68%, respectively). The determined optimum pH and temperature confirm the enzymatic nature of these metabolites.

Role of antioxidant in seed quality- A review

Antioxidant is any substance that delays, prevents or removes oxidative damage to a target molecule. This includes compounds of a non-enzymatic as well as an enzymatic nature. Antioxidant enzymes e.g., superoxide dismutase, glutathione peroxidase, and glutathione reductase, which catalyze free radical quenching reaction. Nutrient-derived antioxidants like ascorbic acid (vitamin C), tocopherols and tocotrienols (vitamin E), carotenoids and other low molecular weight compounds such as glutathione and lipoic acid are involved in neutralizing free radicals. Reactive oxygen species (ROS) occur in tissues and cells and can damage DNA, proteins, carbohydrates and lipids. The ROS comprises both free radical (O2-, superoxide radicals; OH-, hydroxyl radical; HO2-, perhydroxy radical and RO-, alkoxy radicals) and non-radical (molecular) forms (H2O2, hydrogen peroxide and 1O2, singlet oxygen). These deleterious reactions are controlled in part by antioxidants that eliminate ROS and scavenge free radicals. Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. Seed priming methods have been used to increase germination characteristics under stress conditions. The beneficial effects of seed priming are associated with different physiological and biochemical changes.

EFFECT OF PASTEURIZATION CLAIM ON ACCEPTANCE AND PURCHASE INTENTION OF READY-TO-EAT AÇAÍ

The açaí (Euterpe oleracea) is very perishable, due to its microbial,chemical and enzymatic nature. Furthermore, extensive handlingof the product during the production process also contributes toits rapid deterioration and contamination. Results showed the açaías a vehicle for oral transmission of Acute Chagas disease (ACD).The pasteurization, which is an important thermal process in thefood industry, can inactivate the protozoan that transmits the ACD,assuring microbiological food safety. However, heat can aff ectimportant sensory characteristics such as color and fl avor anddecrease açaí acceptance. On the other hand, information aboutthe product can interfere in the consumer’s choice and intention topurchase. The study was conducted with two brands of ready-toeataçaí, pasteurized and unpasteurized. Aff ective acceptance testswere performed with the samples, using the hedonic 9-point scale (1= dislike extremely to 9 = like extremely). Moreover, evaluations alsoincluded consumption frequency , and purchase intention. Resultsdemonstrated that the pasteurization claim, given to consumers,increased (p<0.05) acceptance of the pasteurized sample (7.5a),initially (without the claim) (6.2b) not as well accepted as theunpasteurized sample (7.8a) (p<0.05). Despite that, the claim of notpasteurization did not infl uence the acceptance of the unpasteurizedsample (7.8a), which remained well accepted (p>0.05) by consumers(7.8a). These results reinforce the importance of the eff ect ofinformation on the consumer’s acceptance and purchase intentionof açaí.

EFFECT OF PASTEURIZATION CLAIM ON ACCEPTANCE AND PURCHASE INTENTION OF READY-TO-EAT AÇAÍ1

The açaí (Euterpe oleracea) is very perishable, due to its microbial,chemical and enzymatic nature. Furthermore, extensive handlingof the product during the production process also contributes to itsrapid deterioration and contamination. Results showed the açaí asa vehicle for oral transmission of Acute Chagas disease (ACD). Thepasteurization, which is an important thermal processing in the foodindustry, can inactivate the protozoan that transmits the ACD, assuringthe microbiological food safety. However, heat can aff ect importantsensory characteristics such as color and fl avor and decrease açaíacceptance. On the other hand, information about the product caninterfere in consumer choice and intention to purchase. The studywas conducted with two brands of ready-to-eat açaí, pasteurizedand unpasteurized. Aff ective acceptance tests were performed withthe samples, using the hedonic 9-point scale (1 = dislike extremelyto 9 = like extremely). Moreover, evaluations also included frequencyof consumption, and purchase intention. Results demonstrated thatthe pasteurization claim, given to consumers, increased (p<0.05)acceptance of the pasteurized sample (7.5a), initially (without theclaim) (6.2b) not as well accepted as the unpasteurized sample(7.8a) (p<0.05). Despite this, the claim of not pasteurization didnot infl uence the acceptance of the unpasteurized sample (7.8a),which remained well accepted (p>0.05) by consumers (7.8a). Theseresults reinforce the importance of the eff ect of information on theconsumers’ acceptance and purchase intention of açaí.

Voluntary intake and digestibility of bluestem (Dichanthium annulatum) hay treated with an enzyme or N source

The objective of this study was to evaluate the effect of two additives: one of enzymatic nature [Dyadic® Cellulase PLUS (ENZ)] and liquid urea nitrogen (LU) on crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), voluntary intake (VI) and digestibility of treated bluestem grass (BGH; Dichanthium annulatum) hay fed to rams. Nine young rams were used in a 3 x 3 latin square design with the three treatments: BGH without additive (CON), and with added ENZ or LU. The additives were sprinkled over the hay 24 hours prior to being offered daily at the rate of 4% of the animal body weight (BW). Application of ENZ resulted in no important change in VI or digestibility of dry matter (DM), CP, NDF or ADF; but ENZ tended to slightly reduce (P menor 0.11) NDF content (73.91 vs. 74.27%), and increase (P menor 0.09) ADF content (44.37 vs. 42.87%). Treatment of BGH with LU increased (P menor 0.01) the content of CP (8.11 vs. 6.41%), tended to depress (P menor 0.11) that of NDF (73.00 vs. 74.27%) and increase (P menor 0.09) those of ADF (43.17 vs. 42.87%) and lignin (6.30 vs. 5.89%). It also increased VI of CP (87.46 vs. 67.25%) and tended (P menor 0.06) to increase VI of DM (1027 vs. 986 g) and CP digestibility (61.11 vs. 53.98%). Daily VI of DM as a percentage of BW was not significantly affected by the treatments (3.13, 2.94 and 3.23% for CON, ENZ and LU, respectively).

Metabolism of ethanol to acetaldehyde by rat uterine horn subcellular fractions

Controversial studies from others suggested that alcohol intake could be associated with some deleterious effects in the uterus. Not all the effects of alcohol drinking on female reproductive organs can be explained in terms of endocrine disturbances. Deleterious effect of alcohol or its metabolites in situ could also play a role. Accordingly, we found a metabolism of alcohol to acetaldehyde in the rat uterine horn tissue cytosolic fraction mediated by xanthine oxidoreductase, requiring a purine cosubstrate and inhibited by allopurinol. This activity was detected by histochemistry in the epithelium and aldehyde dehydrogenase activity was detected in the muscular layer and in the serosa. There was a microsomal process, not requiring NADPH and of enzymatic nature, oxygen-dependent and inhibited by diethyldithiocarbamate, diphenyleneiodonium and partially sensitive to esculetin and nordihydroguaiaretic acid. The presence of metabolic pathways in the uterine horn able to generate acetaldehyde, accompanied by a low capacity to destroy it through aldehyde dehydrogenase, led to acetaldehyde accumulation in the uterus during ethanol exposure. Results suggest that any acetaldehyde produced in situ or arriving to the uterine horn via blood would remain in this organ sufficiently to have the opportunity to react with critical molecules to cause deleterious effects.