Chinese Acad Sci, Inst Hydrobiol, State Key Lab Freshwater Ecol & Biotechnol, Wuhan 430072, Hubei, Peoples R China; Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China
WOS标题词:
Science & Technology
; Life Sciences & Biomedicine
类目[WOS]:
Marine & Freshwater Biology
研究领域[WOS]:
Marine & Freshwater Biology
摘要:
Our studies investigated the physico-chemical properties of alkaline phosphatase excreted by D. magna. This cladoceran mainly released alkaline phosphatase, though it also released a small amount of acid phosphatase. The alkaline phosphatase showed a broad pH optimum (8.05-10.0), and had a broad optimum temperature (30-35 degrees C) with a temperature coefficient (Q(10)) of 2.45. The K-m of the enzyme is 0.15 +/- 0.02 mM when p-nitrophenyl phosphate is used as a substrate, and the V-max is 0.43 +/- 0.01 mu M pNP mg(-1) DW h(-1). Even though alkaline phosphatase had been incubated in chloroform saturated with WC medium for 13 days, its activity was 54% that of the original. The enzyme was strongly inactivated by EDTA, and appeared to be zinc dependent. The alkaline phosphatase activity remained constant when D. magna was fed different quantities of Chlorella sp. The sensitivity of D. magna phosphatase activity to phosphate was time-dependent. During the first 16 hrs, the enzyme was insensitive to phosphate addition, after 24 hrs incubation the enzyme became sensitive to phosphate addition.
英文摘要:
Our studies investigated the physico-chemical properties of alkaline phosphatase excreted by D. magna. This cladoceran mainly released alkaline phosphatase, though it also released a small amount of acid phosphatase. The alkaline phosphatase showed a broad pH optimum (8.05-10.0), and had a broad optimum temperature (30-35 degrees C) with a temperature coefficient (Q(10)) of 2.45. The K-m of the enzyme is 0.15 +/- 0.02 mM when p-nitrophenyl phosphate is used as a substrate, and the V-max is 0.43 +/- 0.01 mu M pNP mg(-1) DW h(-1). Even though alkaline phosphatase had been incubated in chloroform saturated with WC medium for 13 days, its activity was 54% that of the original. The enzyme was strongly inactivated by EDTA, and appeared to be zinc dependent. The alkaline phosphatase activity remained constant when D. magna was fed different quantities of Chlorella sp. The sensitivity of D. magna phosphatase activity to phosphate was time-dependent. During the first 16 hrs, the enzyme was insensitive to phosphate addition, after 24 hrs incubation the enzyme became sensitive to phosphate addition.
关键词[WOS]:
PHOSPHORUS-DEFICIENCY
; LAKE
; PHYTOPLANKTON
; ZOOPLANKTON
; ALGAE
; INDICATORS
; WATER
; FOOD
1.Chinese Acad Sci, Inst Hydrobiol, State Key Lab Freshwater Ecol & Biotechnol, Wuhan 430072, Hubei, Peoples R China 2.Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China
Recommended Citation:
Zhao, Xian-Fu; Liu, Guo-Xiang; Hu, Zheng-Yu.Physico-chemical properties of alkaline phosphatases released by a planktonic crustacean, Daphnia magna (Cladocera),CRUSTACEANA,2006,79(6):677-689
