Biochemical properties and evaluation of washing performance in commercial detergent compatibility of two collagenolytic serine peptidases secreted by Aspergillus fischeri and Penicillium citrinum.

Filamentous fungi secrete diverse peptidases with different biochemical properties, which is of considerable importance for application in various commercial sectors. In this study, we describe the isolation of two fungal species collected from the soil of decayed organic matter: Aspergillus fischeri and Penicillium citrinum. In a submerged bioprocess, we observed better peptidase production with the fungus P. citrinum, which reached a peak production at 168 h with 760 U/mL, in comparison with the fungus A. fischeri, which reached a peak production at 72 h with 460 U/mL. In both situations, the fermentative medium contained 0.5% crushed feathers as a source of nitrogen. On performing biochemical characterization, we detected two alkaline serine peptidases: The one secreted by P. citrinum had optimal activity at pH 7.0 and at 45°C, while the one secreted by A. fischeri had optimal activity in pH 6.5-8 and at 55-60°C. Metallic ions were effective in modulating these peptidases; in particular, Cu2+ promoted negative modulation of both peptidases. The peptidases were stable and functional under conditions of nonionic surfactants, temperatures up to 45°C for 1 h, and incubation over a wide pH range. In addition, it was observed that both peptidases had the capacity to hydrolyze collagen and performed well in removing an egg protein stain when supplemented into a commercial powder detergent; this was especially true for the peptidase from P. citrinum.

Nocturnal branched-chain amino acid administration improves protein metabolism in patients with liver cirrhosis: comparison with daytime administration.

BACKGROUND: In an attempt to optimize oral branched-chain amino acid (BCAA) administration to improve serum albumin in cirrhotic patients, we compared the effects of nocturnal and daytime BCAA administration on protein metabolism in cirrhotic patients. METHODS: Twelve cirrhotic patients were enrolled in a short-term study. Patients were administered either conventional daytime BCAA granule or nocturnal BCAA for a week, and metabolic analyses were performed, followed by a crossover study in the next week. Another 12 patients, who showed no improvement of serum albumin level with previous daytime BCAA administration, were randomly assigned to either a nocturnal or a daytime BCAA administration group in a long-term study. RESULTS: Low Fischer's ratio, reduced respiratory quotient, and low serum albumin were observed at entry in cirrhotic patients. Whereas daytime BCAA administration improved nitrogen balance and Fischer's ratio, these 2 were further significantly improved after nocturnal BCAA administration. There were no changes in parameters of energy metabolism throughout the study. In the 3-month follow-up, a significant increase in serum albumin was observed in patients administered nocturnal BCAA but not in those administered daytime BCAA. CONCLUSIONS: Nocturnal BCAA administration improved serum albumin in cirrhotic patients who showed no improvement in serum albumin level with daytime BCAA administration. This effect could be partly caused by the improved protein sparing with this administration method.