Phosphatase activity on the cell wall of Fonsecaea pedrosoi
Phosphatase activity on the cell wall of Fonsecaea pedrosoi
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DOI：
10.1080/10683160310001615399
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发表时间：
2003-12-01
期刊：
影响因子：
2.9
通讯作者：
Meyer-Fernandes, JR
中科院分区：
文献类型：
--
作者：
Kneipp, LF;Palmeira, VF;Meyer-Fernandes, JR
磷酸酶的活性的特点是完整的菌丝体形式的丰塞卡菌pedrocyte，致病真菌，导致着色芽生菌病。在pH5.5时，该菌水解对硝基苯基磷酸（p-NPP）生成对硝基苯酚（p-NP）的速率为12.78 ± 0.53 nmol p-NP/h/mg菌丝干重。p-NPP水解的Vmax和表观Km值分别为17.89 +/- 0.92 nmol p-NP/h/mg菌丝干重和1.57 +/- 0.26 mmol/l。这种活性在pH值增加时被抑制，这一发现与酸性磷酸酶相容。经典的酸性磷酸酶抑制剂如原钒酸钠（Ki = 4.23 μ mol/l）、氟化钠（Ki = 7.53 μ mol/l）和氟化钠（Ki = 126.78 μ mol/l）以剂量依赖方式强烈抑制酶活性。左旋咪唑（1 mmol/l）和酒石酸钠（10 mmol/l）对酶活性无影响。酸性磷酸酶的细胞化学定位显示电子致密的磷酸铈沉积在细胞壁上，通过透射电子显微镜观察。磷酸酶活性在F pedrophilis似乎是与寄生，作为scandulus细胞，这是真菌的形式，主要检测到在着色芽生菌病病变，表现出更高的活动比分生孢子和菌丝体没有。最近从人类着色芽生菌病病例中分离出的一株F pedrophylaxis也显示出酶活性增加，这表明表面磷酸酶的表达可能通过与宿主的相互作用来刺激。
The activity of a phosphatase was characterized in intact mycelial forms of Fonsecaea pedrosoi, a pathogenic fungus that causes chromoblastomycosis. At pH 5.5, this fungus hydrolyzed p-nitrophenylphosphate (p-NPP) to p-nitrophenol (p-NP) at a rate of 12.78 +/- 0.53 nmol p-NP per h per mg hyphal dry weight. The values of V-max and apparent K-m for p-NPP hydrolyses were measured as 17.89 +/- 0.92 nmol p-NP per h per mg hyphal dry weight and 1.57 +/- 0.26 mmol/l, respectively. This activity was inhibited at increased pH, a finding compatible with an acid phosphatase. The enzymatic activity was strongly inhibited by classical inhibitors of acid phosphatases such as sodium orthovanadate (K-i = 4.23 mumol/l), sodium molybdate (K-i = 7.53 mumol/l) and sodium fluoride (K-i = 126.78 mumol/l) in a dose-dependent manner. Levamizole (1 mmol/l) and sodium tartrate (10 mmol/l), had no effect on the enzyme activity. Cytochemical localization of the acid phosphatase showed electrondense cerium phosphate deposits on the cell wall, as visualized by transmission electron microscopy. Phosphatase activity in F pedrosoi seems to be associated with parasitism, as sclerotic cells, which are the fungal forms mainly detected in chromoblastomycosis lesions, showed much higher activities than conidia and mycelia did. A strain of F pedrosoi recently isolated from a human case of chromoblastomycosis also showed increased enzyme activity, suggesting that the expression of surface phosphatases may be stimulated by interaction with the host.