A selective, fast, and effective enzyme assay based on matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) for quantifying β-lactamase, an illegal additive in milk products, has been reported. The strengths of the mass spectrometric assay are its response to all substrate and products, simple and direct detection of the conversion of substrate, and facile determination of enzyme activity. Also, MALDI MS is tolerant to many buffer salts and reagents without the requirement of complicated sample pretreatment procedures. In this study, the approach was used to detect the presence of β-lactamases (BLA) in milk samples. The amount of BLA that could be determined in a milk sample is 6 × 10−3 U·mL−1 by this approach. To test the strategy, it has been applied to the fortified milk (adding a BLA product known as an antimicrobial destroyer). It is then tested whether the pasteurization procedure of the milk process affects the activity of BLA in milk samples. This study offers a perspective into the utility of MALDI-FTMS as an alternative detection tool for BLA screening in milk.
据报道,一种基于基质辅助激光解吸/电离傅立叶变换质谱法(MALDI-FTMS)的选择性、快速、有效的酶测定法可用于定量检测乳制品中的一种非法添加物--β-内酰胺酶。质谱测定法的优点是对所有底物和产物都有反应,能简单直接地检测底物的转化,并能方便地测定酶的活性。此外,MALDI MS 对许多缓冲盐和试剂都有很好的耐受性,无需复杂的样品预处理程序。在本研究中,该方法被用于检测牛奶样品中是否存在β-内酰胺酶(B
LA)。该方法可测定牛奶样本中的 B
LA 量为 6 × 10-3 U-mL-1。为了测试该策略,我们将其应用于强化牛奶(添加一种被称为抗菌素破坏剂的 B
LA 产品)。然后测试了牛奶加工过程中的巴氏杀菌程序是否会影响牛奶样本中 B
LA 的活性。这项研究为 MALDI-FTMS 作为牛奶中 B
LA 筛查的替代检测工具提供了一个视角。