Tryptic digestion of proteins

Alkylammonium acetate buffer systems have also attracted limited attention for the separation of tryptic digests of proteins on octadecyl silica 60). The ammonium formate or trifluoroacetate buffers have also been used in the reversed-phase HPLC separation of the tryptic, chymotryptic, and carboxypeptidase A digests 136) of a-melanotropin and its N,0-diacetylserine analog as well as for enzymatic digests of the adrenocorticotropic family 137). Ammonium bicarbonate eluent systems have proved useful in mapping studies due to the eluent s volatility and differ-... 

The rapid advancement in peptide research over the past 25 years must be attributed, in part, to the effectiveness of high-performance liquid chromatography (HPLC), particularly reversed-phase chromatography, in the separation and analysis of peptides. The resolution and selectivity of this technique allows peptides to be effectively isolated and purified from closely related substances. It also separates most or all of the components of complex biological mixtures such as tryptic digests of proteins. 

Tryptic digests of proteins formed in a cell free system... 

Chen et al. developed an online combination system of CIEF with capillary RP-HPLC (CRPLC) using a microinjector as the interface for 2D separations of complex protein mixtures [144]. The resolving power of a combined CIEF-CRPLC system was demonstrated with tryptic digests of proteins from Drosophila salivary glands. The overall peak capacity was estimated to be around approximately 1800 over a run time of less than 8 hours. 

Microheterogeneous proteins Transferrin Mixtures of drugs, peptides, tryptic digests of proteins, biological fluids Urinary CPlll and CPI... 

Assignment of amino acid sequences and deconvolution of overlapping chromatographic peaks in tryptic digests of proteins... 

Li F, Schmerberg CM, Ji QC. Accelerated tryptic digestion of proteins in plasma for absolute quantitation using a protein internal standard by liquid chromatography/ tandem mass spectrometry. Rapid Commun Mass Spectrom 2009 23(5) 729—732. 

Literature on enzyme microreactors for chemical synthesis is scarce. There is abundant literature, however, on the use of enzymes in microsystems for purposes of DNA analysis, e.g. using the polymerase chain reaction discussed before or DNA restriction fragment analysis [81], for proteomics, such as tryptic digestion of proteins with the enzyme free in solution [82], with trypsin-coated beads trapped in a microreactor [83] or trypsin immobilized on a porous polymer monolith (in a fused-silica capillary) [84]. Also, enzyme microreaction devices have been used extensively for medical diagnostics or immunoassays, e.g. using porous silicon as a support for immobilized enzymes [85]. 

In conclusion, tryptic digestion of proteins and analysis of the resulting peptides by MALDI-TOF MS or LC-MS have proven to be a potent tool to elucidate mechanisms underlying bacterial resistance to antibiotics. Either proteins of interest or protein fractiorts such as outer membrane proteirrs can be analyzed, or the whole proteome of antibiotic-susceptible and -resistant strairrs can be compared. The proteins of interest or the differentially expressed proteirrs can be digested to... 

Figure 35. Doubly charged ions from tryptic digests of protein.s...

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