Substrate specificity of Myriococcum thermophilum cellobiose dehydrogenase on mono-, oligo-, and polysaccharides related to in situ production of H2O2.

Cellobiose dehydrogenase from the ascomycete fungus Myriococcum thermophilum (MtCDH) was tested for the ability to generate bleaching species at a pH suitable for liquid detergents. The catalytic properties of MtCDH were investigated for a large variety of carbohydrate substrates using oxygen as an electron receptor. MtCDH produces H2O2 with all substrates tested (except fructose) but only in the presence of a chelant. Insoluble substrates like cellulose and cotton could as well be oxidized by MtCDH. To enhance the amount of cello-oligosaccharides in solution, different cellulases on cotton were used and in combination with MtCDH an increased H2O2 concentration could be measured. Additionally, the degradation of pure anthocyanins in solution (as model substrates for bleaching) was investigated in the absence and presence of a horseradish peroxidase. MtCDH was able to produce a sufficient amount of H2O2 to decolorize the anthocyanins within 2 h.

Enzymatic reduction of azo and indigoid compounds.

A customer- and environment-friendly method for the decolorization azo dyes was developed. Azoreductases could be used both to bleach hair dyed with azo dyes and to reduce dyes in vat dyeing of textiles. A new reduced nicotinamide adenine dinucleotide-dependent azoreductase of Bacillus cereus, which showed high potential for reduction of these dyes, was purified using a combination of ammonium sulfate precipitation and chromatography and had a molecular mass of 21.5 kDa. The optimum pH of the azoreductase depended on the substrate and was within the range of pH 6 to 7, while the maximum temperature was reached at 40 degrees C. Oxygen was shown to be an alternative electron acceptor to azo compounds and must therefore be excluded during enzymatic dye reduction. Biotransformation of the azo dyes Flame Orange and Ruby Red was studied in more detail using UV-visible spectroscopy, high-performance liquid chromatography, and mass spectrometry (MS). Reduction of the azo bonds leads to cleavage of the dyes resulting in the cleavage product 2-amino-1,3 dimethylimidazolium and N approximately 1 approximately ,N approximately 1 approximately -dimethyl-1,4-benzenediamine for Ruby Red, while only the first was detected for Flame Orange because of MS instability of the expected 1,4-benzenediamine. The azoreductase was also found to reduce vat dyes like Indigo Carmine (C.I. Acid Blue 74). Hydrogen peroxide (H(2)O(2)) as an oxidizing agent was used to reoxidize the dye into the initial form. The reduction and oxidation mechanism of Indigo Carmine was studied using UV-visible spectroscopy.

Increased lipid utilization in weight losing and weight stable cancer patients with normal body weight.

OBJECTIVE: Cachexia and weight loss are frequently seen in cancer patients. We investigated lipid metabolism to elucidate a metabolic basis for adequate nutrition of cancer patients. DESIGN: Lipid metabolism was assessed by indirect calorimetry and triglyceride clearance rates after randomised injection of a lipid bolus (long-chain triglycerides (LCT) or medium-chain triglycerides (MCT) during an euglycemic clamp protocol in cancer patients. SETTING: Rudolf-Virchow Krankenhaus, Berlin, Germany. SUBJECTS: Eighteen patients were included. Twelve patients had upper gastrointestinal cancer: a weight stable cancer group (Caws, n = 6) with a body mass index (BMI) of 22.9 +/- 1.7 kg/m2 and a weight losing cancer group (Cawl, n = 6) with a mean weight loss of 7.4 +/- 3.1 kg or 11% of the initial body weight during the previous three months (present BMI 21.8 +/- 0.8 kg/m2). The data were compared with six control patients with benign gastrointestinal diseases (BMI = 25.0 +/- 0.8 kg/m2). MAIN OUTCOME: Cancer patients had an increased basal lipid oxidation rate that was more pronounced in Cawl (+92% vs +42% in Caws; P < 0.01 and 0.05 vs controls, respectively). Utilisation of LCT was increased in cancer patients, this was most pronounced in Cawl (+150 vs +65% in Caws; P < 0.01 and 0.05, respectively). Metabolically, there were no differences in the utilisation of LCT and MCT/LCT containing lipid emulsions. CONCLUSIONS: Cancer patients have an increased lipid oxidation and an enhanced utilisation of exogeneous lipids. This is most pronounced in Cawl. To prevent further weight loss or to increase body weight, they should increase their fat intake. In contrast, fat-reduced or prudent diets seem to be inadequate for the nutrition of cancer patients.