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Electropray Mass Spectrometry Electropray Mass Spectrometry

What is a Electrospray MS? Hvad er en Electrospray MS?

The Mass of Proteins can be Precisely Determined Electrospray mass spectrometry Massen af proteiner kan Netop beslutsom Electrospray mass spectrometry

The very low volatility of proteins was a barrier for many years to using mass spectrometry, an estazblished analytical technique in organic chemistry.  This difficulty has been circumvented by the recent introduction of electrospray ionization mass spectrometry.  A protein sample in an acidic volatile solvent is sprayed into a mass spectrometer.  The solvent surrounding individual droplets evaporates rapidly in the vacuum chamber of the instrument, leaving unfragmented bare protein molecules carrying multiple positive charges.  These charged protein molecules are accelerated by an electric field and then deflected by a magnetic field.  They are separated according to the ratio of their mass to their charge.  The mass spectrum of a pure protein shows a set of peaks corresponding to different numbers of bound protons.  Because adjacent peaks in the mass sopectrum arise from proteins containing n-1, n, and n+1 bound protons, the mass of the parent protein molecule can be deduced.  Mass spectrometric determinations are accurate to about 1 part in 104, which means that the mass of a 1-kd protein can be measured to within 1 dalton. Den meget lav volatilitet af proteiner var en barriere for mange år at bruge mass spectrometry, en estazblished analytiske teknik i organisk kemi. Denne vanskelighed er blevet omgået af den nylige indførelse af electrospray ionization mass spectrometry. Et protein prøve i et surt flygtige opløsningsmidler er sprøjtet ind i en masse spektrometer. Opløsningsmidlet omkringliggende enkelte dråber fordamper hurtigt i vakuum kammer af instrumentet, der forlader unfragmented bare protein molekyler transporterer flere positive afgifter. Disse afholdes protein molekyler er fremskyndet af et elektrisk felt og derefter afledt af et magnetisk felt. De er adskilles efter forholdet mellem deres masse til deres afgift. Massen spektrum af en ren protein viser et sæt af toppene svarende til forskellige numre af bundet protoner. Fordi tilstødende toppe i massen sopectrum hidrører fra proteiner indeholder n-1, n, og n +1 bundet protoner, massen af moderselskabet protein molekyle kan udledes. Masse spektrometrisk afgørelser er korrekte til omkring 1 del i 104, hvilket betyder, at massen af en 1-kd protein kan måles inden for 1 dalton.