Matrix-assisted laser desorption ionization experiment

King, R. C., Goldschmidt, R., Xiong, Y., and Owens, K. G., Mechanistic Studies of the Cationization of Synthetic Polymers by Alkaly Metals in the Matrix-assisted Laser Desorption/Ionization Experiment. 43rd ASMS Conf. Mass Spectrom., Atlanta, GA, 1237, 1995. 

The two membranes most used for protein work are nitrocellulose and polyvi-nylidene fluoride (PVDF). Both bind proteins at about 100 pg/cm2. Nitrocellulose is the best membrane to use in the initial stages of an experiment. PVDF is used when proteins are to be sequenced or placed into a (matrix-assisted laser desorption ionization) mass spectrometer. PVDF can withstand the harsh chemicals of protein sequenators and the heat generated by mass spectrometer lasers, whereas nitrocellulose cannot. 

To study the communication between the El and E2 components, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been very useful, as it can also be utilized to determine the time course of reductive acetylation of the E2 component by the El component and pyru-vate7 ° While the wild-type Elec can reductively acetylate the E2ec component in less than 30 s (the current limit for manual quench), with the inner loop variants, both unacetylated and acetylated forms are clearly visible even after 30 min, that is, the reductive acetylation was incomplete even after this time period (Figure 17). This experiment is made possible by two observations (1) the reductively acetylated E2 component is stable under acidic conditions and (2) the lipoyl domains of the E2 component are resistant to trypsinolysis. 

Because of some of the problems with bioassays and immunoassays, liquid chromatography (LC)-based techniques are increasingly applied as an alternative. While modern LC-based assays have a comparable sensitivity to immunoassays, they oftentimes are characterized by a higher selectivity [18, 19]. Muller et ah, for example, used LC/mass spectrometry with matrix-assisted laser desorption ionization in ex vivo pharmacokinetic studies in combination with enzyme inhibition experiments to investigate the complex metabolism of dynorphin Al-13, a peptide with opioid activity, up to the fifth metabolite generation [20, 21]. 

Y., Sep Hieng, S., M6nard, A., and Megraud, F. (2011) Matrix-assisted laser-desorption/ionization biotyper experience in the routine of a university hospital. Clin. Microbiol Infect., 17, 533-538. 

Nevertheless, planar electrophoretic techniques are very popular in biotechnological and biochemical laboratories. There is still no online interface, directly linking such techniques with mass spectrometric detectors. A handful of experiments were described, regarding the identification of proteins transferred onto the membrane after immunoblotting [6,7]. Secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) techniques were used for the direct analysis of intact proteins or after sputtering blots with trypsin solution for digestion... 

IMS experiments may be performed using one of several MS ionization techniques secondary ion mass spectrometry (SIMS), laser desorption/ionization (LDI), desorption electrospray ionization (DESI), and matrix-assisted laser desorption/ionization (MALDI) (2). In general, these techniques offer complementary capabilities (3). SIMS imaging is favored for higher spatial resolution imaging over a low mass range (<1,000 Da), MALDI IMS covers a much wider mass range (up to and over 100,000 Da) but at somewhat lower spatial resolution, and DESI uses ambient pressure for analysis of small molecules but at lower spatial resolution. 

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