A total of about 30 families of metalloproteases have been documented, out of which 17 contain only endopeptidases, 12 contain only exopeptidases, and 1 (M3) contains both endo- and exopeptidases [4, 5] (Table 1).
Serine proteases are found in the exopeptidase, endopeptidase, oligopeptidase, and omegapeptidase groups [4, 5].
A sequence-specific
exopeptidase activity test (SSEAT) for functional biomarker discovery.
A sequence-specific
exopeptidase activity test (SSEAT) for "functional" biomarker discovery.
It was hypothesized that these are derived ex vivo during clotting, representing surrogate markers generated by alterations in serum concentrations or activities of the tumor-derived
exopeptidases.
These patterns originate from proteolytic processing of high-abundant proteins ex vivo by a multitude of proteases that include endopeptidases and
exopeptidases (14).
Peptides of similar antigenicity are often formed by posttranslational modifications essential for physiological function or consecutive peptide chain truncation by
exopeptidases.
Fibrinopeptide A is released faster than fibrinopeptide B, and the fibrinopeptides are trimmed by exopeptidases; hence, the amounts and molecular forms of these short peptides depend on the extent and duration of clotting of an individual specimen (38-40).
Multiple molecular forms of serum amyloid A, related to trimming of the peptide chain by exopeptidase, have been noted by MALDI- or SELDI-TOF MS (30, 46-50).
Flavourzyme that is an exopeptidase, produced the lowest amount of peptide with small molecular size (15.4% and 19.8% of soybean and rice, respectively), whereas Alcalase as the strongest endopeptidase in this study can provide the most amount of peptides with small sizes (<4 kDa) (Figure 1).
Addition of plant protein hydrolysates into the medium without FBS had shown a slight improvement in the cell growth (cell died after 4 to 5 days) with hydrolysates from Alcalase for both soybean and rice hydrolysates (Figure 2A and 2B).The protein extracts by Flavourzyme as an exopeptidase did not have significant effect on cell culture.
Flavorpro[TM] 937MDP is an
exopeptidase preparation with low levels of endopeptidase activity.
