Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.16.3.1 (ceruloplasmin)
 5,074 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The oxidation of 2-keto-4-thiomethyl butyric acid (KTBA) and methionine to ethylene has been used to evaluate generation of ferryl species or hydroxyl radicals by H2O2-activated haemproteins or free ferric ions. Hydrogen peroxide was generated by a glucose oxidase-glucose system at a rate of 1 microM/min. Free ferric in the presence of H2O2 oxidizes KTBA, and this was highly inhibited by hydroxyl radical scavengers, caeruloplasmin, superoxide dismutase (SOD) and EDTA. However, when metmyoglobin, methaemoglobin (MtHb) or horseradish peroxidase (HRP) were tested in the same model system, hydroxyl radical scavengers suppressed partially KTBA oxidation and caeruloplasmin, SOD and EDTA failed to inhibit the reaction. Cytochrome-c was found to be a weak promoter of KTBA oxidation in the presence of H2O2. Methionine was oxidized to ethylene by an active system which generates hydroxyl radicals, but not by H2O2-activated metmyoglobin. Ferric ions chelated to membranes or ADP in the presence of H2O2 generated enzymatically, initiated membranal lipid peroxidation only in the presence of ascorbic acid, and this was inhibited by EDTA. In contrast, metmyoglobin and methaemoglobin activated by H2O2 generated by the same system, initiated membranal lipid peroxidation and this was not inhibited by EDTA. It is concluded that ferryl and not HO. is the main oxidant in systems containing myoglobin and haemoglobin activated by low concentrations of H2O2.
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PMID:The generation of ferryl or hydroxyl radicals during interaction of haemproteins with hydrogen peroxide. 285 14

We evaluated the effect of feed additives on the risk of ruminal acidosis in Holstein heifers (n = 40) fed starch and fructose in a challenge study. Heifers were randomly allocated to feed additive groups (n = 8 heifers/group): (1) control (no additives); (2) virginiamycin (VM); (3) monensin + tylosin (MT); (4) monensin + live yeast (MLY); and (5) sodium bicarbonate + magnesium oxide (BUF). Heifers were fed 2.5% of body weight (BW) dry matter intake (DMI) per day of a total mixed ration (62:38 forage:concentrate) and feed additives for a 20-d adaptation period. Fructose (0.1% of BW/d) was included for the last 10d of the adaptation period. On d 21, heifers were fed to target a DMI of 1.0% of BW of wheat, fructose at 0.2% of BW, and their feed additives. Rumen fluid samples obtained by stomach tube and blood samples were collected weekly as well as during a 3.6-h period on challenge day (d 21). Virginiamycin and BUF groups maintained a consistently high DMI across the 20-d adaptation period. The MLY heifers had low DMI of the challenge ration. Average daily gain and feed conversion ratio were not affected by feed additives. All rumen and plasma measures changed weekly over adaptation and over the challenge sampling period with the exception of rumen total lactate and histamine concentrations, plasma oxidative stress index, and ceruloplasmin. Substantial within- and between-group variation was observed in rumen and plasma profiles at challenge sampling. No significant group changes were observed in rumen total volatile fatty acids, propionate, acetate-to-propionate ratio, isobutyrate, caproate, isovalerate, total lactate, d- and l-lactate, and pH measures on challenge day. Acetate concentration was increased in the BUF and control groups on challenge day. Butyrate concentration was lower in the MLY and MT groups compared with other groups at challenge. Valerate concentrations were lowest in the control, VM, and BUF groups and lactate concentrations were numerically lower in the MLY, VM, and BUF groups. Total lactate concentrations were >10mM for each group throughout the challenge. Ammonia concentrations were lower in the MLY and MT groups. Histamine concentrations were decreased in MLY and increased in the VM and BUF groups. Plasma oxidative stress measures were not influenced by feed additives weekly or on challenge day, except for an increase in biological antioxidant potential in the control, VM, and MT groups on challenge day. Despite the large within-animal variation, all feed additives modified rumen function and may influence the risk of acidosis by different mechanisms; however, none stabilized the rumen in all heifers.
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PMID:Effects of feed additives on rumen and blood profiles during a starch and fructose challenge. 2421 Apr 82