The Use of Other Acidic Proteases After Expression or Extraction

4 The Use of Other Acidic Proteases After Expression or Extraction 

Both commercially available fungal proteases have shown their capacity to be used for HX-MS experiments, with specificities complementary to pepsin. However, their lack of purity hampers their immobilization which was shown to present several advantages for pepsin. 

Proteases for Hydrogen Exchange Mass Spectrometry 99 Pepsin cleavage preference 

Two years before, another group produced, in E. coli, two pepsin isoforms from Antarctic rock cod Trematomus bernacchii, pepsins A1 and A2 [34]. Acid endoproteases from cold-adapted organisms could be very interesting to study because of the needs in highly active proteases in cold conditions, required in HX-MS. Nevertheless, both A1 and A2 enzymes present a lower specific activity in cold conditions than commercially available porcine pepsin. Moreover, the specificity of both enzymes is very close to porcine pepsin even if pepsin A1 presents some 

More recently, Engen s group also investigated a new aspartic protease from the stomach of the rice field eel (Monopterus albus Zuiew) and compared digestion efficiency and specificity to porcine pepsin and protease type XIII. They found unique cleavage specificity for rice field eel pepsin at Arg, Asp, and Gly [15]. 

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