Mass spectrometromety

the basic principle of
technology is that after the sample molecular ionization, the molecular weight is separated and determined according to the difference of the load ratio (m/e ) between different ions. The principle is not new, but two new ionization techniques that emerged in the early 80s , enabling mass spectrometrometromets to go from analyzing only small molecule volatiles to postgraduate martial arts molecules.




, two new ionization technologies were invented, one of which is media-assisted laser de-absorption / ionization (matrix-assisted laser desorption/ionization


,

maldi


), the other is electrospray ionization (electrospray


,
< br/>ESI


). These techniques can quickly and extremely accurately determine the molecular weight of biometric molecules, and in combination with various new mass spectrometrometrometrometization techniques,
proteins
can be studied at various levels, opening up new avenues for protein research, from protein in-depth to advanced structural studies, as well as interactions between proteins.


In addition, for protein and
polypeptide
, the development of mass spectrometry has an important use is peptide sequencing. This is the use of series mass spectrometrography (Tandem-MS ), i.e. in the first stage of mass spectrometromety to obtain peptide molecular ions ,select the target peptide ions as parent ions, colliding with inert gases, so that the peptide bonds in the peptide chain break, forming a series of ions, that is,

-end debris ion series (Bseries) and C -end debris ion series (Yseries), these fragment ion series can be analyzed to produce a
amino acid
sequence of peptide segments. Recently,




applications such as
Nano-electrospray ) have been able to measure peptide sequences at lower fmol


measurements. In

MALDI-MS , in recent years the available source post-decay - substation-assisted laser de-absorption ionization mass spectrometry (post-source-MALDI-MS
,

peptide sequences using PSD-MALDI-MS ) technology.


Unlike the above method peptide sequence, Chaitand other development of a method called "protein ladder sequencing ", through Edman


degradation method the modification, resulting in a series of Nend residuals of the peptide segment, with MALDI-MSto measure the quality of these peptide segments, thereby inferring the Nend sequence.

Patterson


Y enzymatic solution and combined with MALDI-TOF MS mass analysis also measured the C end of the peptide sequence.

Mann


with series mass spectrometrometrometromet technology to analyze peptide segments such as this information: N end segment quality, C end segment quality and the middle few The sequence of residues, called the peptide sequence tag (peptide sequence tag , PST ), is considered to be more restrictive than some peptide sequence information in the inventory.


Mass spectrometry has many advantages and can also be used for post-translation modification analysis (glycosylation, phosphorylation), but is currently only applicable to 20 peptide segments below amino acids. In addition, there are inherent limitations, such as Leu




Ile


,



Lys


and Gln cannot be distinguished, and the inherent sequences of some peptides cannot be determined by mass spectrometrography.