A matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS)-based assay was developed for kinetic measurements and inhibitor screening of acetylcholinesterase. Here, FTMS coupled to MALDI was applied to quantitative analysis of choline using the ratio of choline/acetylcholine without the use of additional internal standard, which simplified the experiment. The Michaelis constant (K m ) of acetylcholinesterase (AChE) was determined to be 73.9 mol L Ϫ1 by this approach. For Huperzine A, the linear mixed inhibition of AChE reflected the presence of competitive and noncompetitive components. The half maximal inhibitory concentration (IC 50 ) value of galantamine obtained for AChE was 2.39 mol L Ϫ1 . Inhibitory potentials of Rhizoma Coptidis extracts were identified with the present method. In light of the results the referred extracts as a whole showed inhibitory action against AChE. The use of high-resolution FTMS largely eliminated the interference with the determination of ACh and Ch, produced by the low-mass compounds of chemical libraries for inhibitor screening. The excellent correlation with the reported kinetic parameters confirms that the MS-based assay is both accurate and precise for determining kinetic constants and for identifying enzyme inhibitors. The obvious advantages were demonstrated for quantitative analysis and also high-throughput characterization. This study offers a perspective into the utility of MALDI-FTMS as an alternate quantitative tool for inhibitor screening of

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Magnetic graphite carbon spheres (MGCSs) with well-distributed Fe 3 O 4 magnetic nanoparticles were synthesized via the following steps. The colloidal carbon spheres (CCSs) with uniformly dispersed Fe(II) and large numbers of hydroxyl groups were synthesized via synchronous hydrothermal reaction of glucose and ferrous gluconate. The CCSs were then converted to MGCSs via consequent thermal treatment. In addition, the hydroxyl groups of the as-prepared CCSs were also utilized to adsorb Ag + ions or condensate with Ti-OH. Following a thermal treatment, composite MGCS@Ag or MGCS@TiO 2 microspheres were fabricated. The results of SEM, TEM and XRD revealed that MGCSs with an average diameter of 1 mm were synthesized; and magnetic Fe 3 O 4 nanoparticles with diameters from 20 to 25 nm were uniformly distributed in MGCSs, which indicated that Fe(II) in the CCSs not only changed into magnetic Fe 3 O 4 nanoparticles, but also worked as a catalyst for the graphitization of amorphous carbon during the thermal treatment. Such a strategy gave at least two advantages. First, the protective effect on the magnetic nanoparticles and mechanical strength of the graphite carbon may improve the capability and feasibility of practical applications. Synchronously, the MGCSs not only have well adsorbing properties as carbon materials, but also possess unusual adsorbing behaviours for heavy metal ions and noble metal ions, which have significant potential applications in the treatment of polluted water and the recovery of noble metals. Second, the synthesis of composite MGCSs may further expand the scope of the applications. For example, the MGCS@Ag and MGCS@TiO 2 microspheres prepared in this effort exhibited excellent antibacterial activity and selective enrichment of phosphopeptides, respectively.

A selective, fast, and effective enzyme assay based on matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) for quantifying beta-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 beta-lactamases (BLA) in milk samples. The amount of BLA that could be determined in a milk sample is 6 x 10(-3) U x 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.

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