β-N-Acetyl-D-glucosaminidase （NAGase, EC.3.2.1.52） is chitinolytic enzymes and disintegrate dimmer and trimer a composition of oligomers of N-acetyl-β-D-glucosamine （NAG） into monomer. Prawn （P. vannamei） NAG...β-N-Acetyl-D-glucosaminidase （NAGase, EC.3.2.1.52） is chitinolytic enzymes and disintegrate dimmer and trimer a composition of oligomers of N-acetyl-β-D-glucosamine （NAG） into monomer. Prawn （P. vannamei） NAGase is involved in digestion and molting processes. Some pollutants in seawater affect the enzyme activity causing loss of the biological function of the enzyme, which affects the exuviating shell and threatens the survival of the animal. The effect of formaldehyde on prawn （P. vannamei） β-N-acetyl-D-glucosaminidase activity for the hydrolysis of pNP-NAG has been studied. The results show that formaldehyde, at appropriate concentrations, can lead to reversible inactivation of the enzyme, and the IC50 is estimated to be 1.05mol· L^-1. The inactivation mechanism obtained from Lineweaver-Burk plots shows that the inactivation of the enzyme by formaldehyde belongs to the competitive type. The inactivation kinetics of the enzyme by formaldehyde has been studied using the progress-of-substrate-reaction method described by Tsou, and the rate constants have been determined. The results show that k＋0 is much larger than k-0, indicating the free enzyme molecule is fragile in the formaldehyde solution.展开更多
Objective. The goal of this paper is to investigate the relationship between the N-glycosylation of acetylglucosaminyltransferase V(Glc NAcT-V) and its activity and to know which site among the 6 N-glycosylation sites...Objective. The goal of this paper is to investigate the relationship between the N-glycosylation of acetylglucosaminyltransferase V(Glc NAcT-V) and its activity and to know which site among the 6 N-glycosylation sites in the GlcNAcT-V gene is the most important. Methods.Wild type of GlcNAcTV was transfected into COS7 cells and its activity was measured 48 h later. The first site (Asn 110) was mutated with sitedirected mutagenesis and transfected into COS7 cells. Results. It was found that after the cells were added tunicamycin(TM, 1 μ g/ml), the activity was 117% of the wild type. The activity of the cells with mutating GlcNAcTV was about 120% of the wild type RTPCR showed that there was no significant change in mRNA expression among the three groups. Conclusion.The Nglycosylation is important for its activity. Our results suggest that the Nlinked carbohydrates on GlcNAcTV are required for the posttranscriptional activity of the enzyme.展开更多
N-acetyl-glucosamine, the monomer of chitin, was cyclo-condensed with L-cysteine to prepare thiazolidine derivative： 2-N-acetyl-glucosamine-thiazolidine-4（R）-carboxylic acid （GlcNAcCys）. The stability of GlcNAcCy...N-acetyl-glucosamine, the monomer of chitin, was cyclo-condensed with L-cysteine to prepare thiazolidine derivative： 2-N-acetyl-glucosamine-thiazolidine-4（R）-carboxylic acid （GlcNAcCys）. The stability of GlcNAcCys was evaluated by high performance liquid chromatography （HPLC） measurement. The results showed that GlcNAcCys was more stable than other TCA derivatives, especially in alkaline condition. The direct in vitro antioxidative properties of GlcNAcCys were investigated by using UV radiation-induced lipid peroxidation （LPO） in mitochondria and nuclei and . OH-induced LPO in red blood cell （RBC） ghosts models. UV radiation caused dose-dependent LPO in both mitochondria and nuclei. This effect was catalyzed by addition of Fe^2 ＋ while prevented by co-incubation with GlcNAcCys. When nuclei and mitochondria was treated with 100μl, 300μl, 500μl of GlcNAcCys and co-incubated at 37℃ for 30min, LPO was decreased to 96%, 72%, 68% in nuclei and 95%, 72%, 68% in mitochondria when compared to the UV radiation group respectively. Hydroxyl radicals （. OH） generated by Fenton reaction induced LPO in RBC ghosts. Pretreatment of RBC ghosts with GlcNAcCys could induce antioxidant RBC ghosts and inhibit concentration-dependent malondialdehyde （MDA） formation in antioxidant RBC ghosts. Its inhibition percent was 14%, 35%, 36%, 42% at 10, 20, 30, 40mg/ml respectively. In a conclusion, the data suggest that GlcNAcCys has antioxidant ability and can significantly inhibit lipid peroxidation in biological samples tested in vitro.展开更多
OBJECTIVE: To investigate changes in renal function, urine N-acetyl-beta-D-glucosaminidase enzyme (N-AG),liver function, myocardial enzymes, the pathology of renal damage and the mechanism of acute renal failure (ARF)...OBJECTIVE: To investigate changes in renal function, urine N-acetyl-beta-D-glucosaminidase enzyme (N-AG),liver function, myocardial enzymes, the pathology of renal damage and the mechanism of acute renal failure (ARF) associated with fish gall bladder poisoning. METHODS: Eleven patients with acute fish gall bladder poisoning were consecutively admitted to our hospital from September 1997 to October 1999. Renal function, urine N-AG enzyme, liver function, and myocardial enzymes were assayed before and after treatment. One patient consented to a kidney biopsy and the pathology of renal damage was observed under light and electron microscopes. RESULTS: All patients had multiple organ dysfunction syndrome (MODS) and 11 patients suffered from ARF. Ten patients had liver dysfunction, ten patients had poisonous myocarditis, and 8 patients had gastrointestinal dysfunction. Renal function, urine N-AG enzyme, liver function, and myocardial enzymes were significantly improved after treatment compared with those of before treatment (P展开更多
文摘β-N-Acetyl-D-glucosaminidase （NAGase, EC.3.2.1.52） is chitinolytic enzymes and disintegrate dimmer and trimer a composition of oligomers of N-acetyl-β-D-glucosamine （NAG） into monomer. Prawn （P. vannamei） NAGase is involved in digestion and molting processes. Some pollutants in seawater affect the enzyme activity causing loss of the biological function of the enzyme, which affects the exuviating shell and threatens the survival of the animal. The effect of formaldehyde on prawn （P. vannamei） β-N-acetyl-D-glucosaminidase activity for the hydrolysis of pNP-NAG has been studied. The results show that formaldehyde, at appropriate concentrations, can lead to reversible inactivation of the enzyme, and the IC50 is estimated to be 1.05mol· L^-1. The inactivation mechanism obtained from Lineweaver-Burk plots shows that the inactivation of the enzyme by formaldehyde belongs to the competitive type. The inactivation kinetics of the enzyme by formaldehyde has been studied using the progress-of-substrate-reaction method described by Tsou, and the rate constants have been determined. The results show that k＋0 is much larger than k-0, indicating the free enzyme molecule is fragile in the formaldehyde solution.
文摘Objective. The goal of this paper is to investigate the relationship between the N-glycosylation of acetylglucosaminyltransferase V(Glc NAcT-V) and its activity and to know which site among the 6 N-glycosylation sites in the GlcNAcT-V gene is the most important. Methods.Wild type of GlcNAcTV was transfected into COS7 cells and its activity was measured 48 h later. The first site (Asn 110) was mutated with sitedirected mutagenesis and transfected into COS7 cells. Results. It was found that after the cells were added tunicamycin(TM, 1 μ g/ml), the activity was 117% of the wild type. The activity of the cells with mutating GlcNAcTV was about 120% of the wild type RTPCR showed that there was no significant change in mRNA expression among the three groups. Conclusion.The Nglycosylation is important for its activity. Our results suggest that the Nlinked carbohydrates on GlcNAcTV are required for the posttranscriptional activity of the enzyme.
文摘N-acetyl-glucosamine, the monomer of chitin, was cyclo-condensed with L-cysteine to prepare thiazolidine derivative： 2-N-acetyl-glucosamine-thiazolidine-4（R）-carboxylic acid （GlcNAcCys）. The stability of GlcNAcCys was evaluated by high performance liquid chromatography （HPLC） measurement. The results showed that GlcNAcCys was more stable than other TCA derivatives, especially in alkaline condition. The direct in vitro antioxidative properties of GlcNAcCys were investigated by using UV radiation-induced lipid peroxidation （LPO） in mitochondria and nuclei and . OH-induced LPO in red blood cell （RBC） ghosts models. UV radiation caused dose-dependent LPO in both mitochondria and nuclei. This effect was catalyzed by addition of Fe^2 ＋ while prevented by co-incubation with GlcNAcCys. When nuclei and mitochondria was treated with 100μl, 300μl, 500μl of GlcNAcCys and co-incubated at 37℃ for 30min, LPO was decreased to 96%, 72%, 68% in nuclei and 95%, 72%, 68% in mitochondria when compared to the UV radiation group respectively. Hydroxyl radicals （. OH） generated by Fenton reaction induced LPO in RBC ghosts. Pretreatment of RBC ghosts with GlcNAcCys could induce antioxidant RBC ghosts and inhibit concentration-dependent malondialdehyde （MDA） formation in antioxidant RBC ghosts. Its inhibition percent was 14%, 35%, 36%, 42% at 10, 20, 30, 40mg/ml respectively. In a conclusion, the data suggest that GlcNAcCys has antioxidant ability and can significantly inhibit lipid peroxidation in biological samples tested in vitro.
基金ThisworkwassupportedbyagrantfromtheMedicalScienceFoundationofHunanHealthAdministration (No 983 2 9)
文摘OBJECTIVE: To investigate changes in renal function, urine N-acetyl-beta-D-glucosaminidase enzyme (N-AG),liver function, myocardial enzymes, the pathology of renal damage and the mechanism of acute renal failure (ARF) associated with fish gall bladder poisoning. METHODS: Eleven patients with acute fish gall bladder poisoning were consecutively admitted to our hospital from September 1997 to October 1999. Renal function, urine N-AG enzyme, liver function, and myocardial enzymes were assayed before and after treatment. One patient consented to a kidney biopsy and the pathology of renal damage was observed under light and electron microscopes. RESULTS: All patients had multiple organ dysfunction syndrome (MODS) and 11 patients suffered from ARF. Ten patients had liver dysfunction, ten patients had poisonous myocarditis, and 8 patients had gastrointestinal dysfunction. Renal function, urine N-AG enzyme, liver function, and myocardial enzymes were significantly improved after treatment compared with those of before treatment (P
