摘要
目的:建立一种测定壳聚糖酶活力的新方法——3-甲基-2-苯并噻唑啉酮腙盐酸盐水合物(MBTH)法。方法:以动力学法通过测定水解过程中壳聚糖释放还原端基的速率来计算酶活力,并以测定纤维素酶中壳聚糖酶的微量活力为例,对测定过程中的几个关键参数进行讨论。结果:在37℃、pH6.0酶解条件下,底物壳聚糖溶液的测定质量终浓度需达到2mg/mL以上;酶解反应时间控制在60min内为宜,可以用终点法定量测得壳聚糖酶活力。结论:通过比较MBTH法、DNS法和铁氰化钾法发现MBTH法更准确、更灵敏、检测范围宽、操作简便。其检测限为13mU/mL,而铁氰化钾法是该法的1.6倍,DNS法是该法的116倍。应用本法所测其酶解壳聚糖的Km值为0.12mg/mL,而用DNS法则较难准确测得。
A novel spectrophotometric method for the quantitative assay of chitosanolytic enzyme activity using 3-methyl-2benzothiazolinone（MBTH） was estalished.The proposed method was based on measuring the reducing ends released during the enzymatic degradation of chitosan with the non-specific enzyme cellulase.The effects of several key hydrolysis parameters on activity assay were discussed and investigated by multiple-point procedures.The results showed that the substrate concentration was required to be no less than 2 mg/mL with an initial pH of 6.0,and the hydrolysis was allowed to proceed for no more than 60 min at 37 ℃ before end-point measurement.In comparison with the 3,5-dinitrosalicylic acid（DNS） method and the potassium ferricyanide method,the MBTH method provided higher accuracy and sensitivity,wider detection range and simpler operation,and showed a limit of detection of 13 mU/mL,which was 1.6 times smaller than that observed for the potassium ferricyanide method and 116 times smaller than that observed for the DNS method.The Kmfor chitosan hydrolysis determined by the MBTH method was 0.12 mg/mL,whereas accurrate Kmmeasurement was difficult to achieve in the DNS method.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2013年第9期277-281,共5页
Food Science
