摘要
采用紫外分光光度法测定栉孔扇贝(Chlamys farreri)血淋巴中酯酶的活性,并研究底物、抑制剂、激活剂、温度、pH对酯酶活力的影响及酶的热稳定性。结果表明,栉孔扇贝血清与血细胞中均存在酯酶,且血细胞中的酶活力高于血清。血清与血细胞中酯酶的最适作用底物有所不同,血清中为α-醋酸萘酯,而血细胞中为α-丁酸萘酯。当以α-醋酸萘酯为底物时,血清中酯酶的最适温度为45℃,最适pH值为7.5;以α-丁酸萘酯为底物时,血清中酯酶的最适温度为40℃,最适pH值为8.0。以α-醋酸萘酯及α-丁酸萘酯为底物分别测定酶的热稳定时,酶活力变化相似,在20℃时活力最高,而后缓慢下降。栉孔扇贝血淋巴中酯酶属中温型中性酶类,低温下较稳定,底物专一性不强,血清中的酯酶可能来自血细胞,该酶在贝类的免疫防御中可发挥重要的作用。[中国水产科学,2006,13(1):39-44]
Esterases are a large and diberse group of hydrolases that hydrolyze numerous substrates including esters and certain nonester substrates. In this study, the activity and property of esterases in haemolymph of scallop Chlamys farreri were assayed with spectrophotometric method. The activity of esterases in both serum and haemocytes of Chlarnys farreri was detected, and the activity of esterases in serum was higher than that in the haemocytes. The optimum substrate of esterases in serum was α-naphthyl acetate, but in haemocytes was α-naphthyl butyrate. Several inhibitor or activator had effect on activity of esterases in serum with the substrate being α-naphthyl acetate. The esterases activity was inhibited fully, respectively by 1 mmol/L CuSO4, 1 mmol/L Pb（NO3）2, 0.1 mmol/L PCMB and pronouncedly by 10 mmol/L EDTA. The esterases activity was enhanced by 10 mmol/L β-phenylpropionic acid, 1 mmol/L L-cysteine, 0.1 mmol/L physostigmine, and the highest activity was obtained with physostigmine. As the substrate of esterases in serum was α-naphthyl acetate, the optimum temperature for the reaction was 45℃, and the optimum pH was 7.5; and as the substrate of esterases in serum was a-naphthyl butyrate, the optimum temperature was 40℃, and the optimum pH was 8.0. The thermal stability of esterases in serum was similar with either α-naphthyl acetate or α-naphthyl butyrate being substrate, and the esterases thermal stability was the highest at the temperature of 20 ℃, and the thermal stability became descending with the temperature increasing, and the enzyme activity value was decreased by 75 % after the serum was incubated at 80℃ for 10 min. The results suggest that the activity levels of esterases in haemolymph of Chlamys farreri is stable at low temperature. The substrate specificity of the esterase is not strict. The esterases in serum may come from haemocytes. The esterases in haemolymph of Chlamys fizrreri may play an important role in protection from pathogens.
出处
《中国水产科学》
CAS
CSCD
北大核心
2006年第1期39-44,共6页
Journal of Fishery Sciences of China
基金
国家"973"计划资助项目(G1999012005)
关键词
栉孔扇贝
血淋巴
酯酶
酶活性
Chlamys farreri
haemolymph
esterase
enzyme activity
