Development Of MALDI-TOF MS And Research On Optimization Of Experimental Conditions

Matrix assisted laser desorption time-of-flight mass spectrometry(MALDI-TOF MS)is a powerful tool for protein identification,microbial analysis and oligonucleotide analysis.MALDI-TOF technology and MALDI-TOF MS instruments have been developed rapidly in recent years and have been widely used.Linear MALDI-TOFMS has the advantage of high upper limit of mass analysis.After introducing the principle of MALDI-TOF technology,this paper presents a development scheme of linear MALDI-TOF MS instrument which can be used for high mass protein detection.The vacuum injection system of the instrument was developed to meet the requirements of the instrument under vacuum conditions and without destroying the original vacuum.The ion source part of the instrument was developed,and the laser light path of the ion source was designed.The laser energy reached the requirement of matrix and sample ionization.In order to improve the resolution of the time-of-flight mass analyzer,a delay extraction module and an ion lens module were designed and the suitable value of high voltage in the ion-optic system was simulated.The data acquisition and data processing system of the instrument are designed to realize the processing of the ion signal and the simple processing of the subsequent data.To achieve the effective control of each module,we developed the software system of the instrument.Direct detection of large-quality protein,making the pre-treatment process simple,and the amount of data greatly reduced,helps in the future microbial identification work to simplify the experimental method.Based on the AB 4700 series MALDI-TOF MS,the experimental conditions for the detection of large mass protein in linear mode were optimized.Different parameters of the laser intensity and the delay extraction time were selected for the experiment.Finally,we pick the experimental conditions to reach the the best signal-to-noise ratio and the resolution.In this paper,the optimal conditions were used to detect enterococcus faecalis directly,and the peaks of four large-quality proteins were obtained.Compared with the peaks after pre-processing of the microorganism including culture-purification-hydrolysis,it is easier to process and analyze the data.