Biomedical Engineering Reference
In-Depth Information
Figure 3.
Protease catalysis of peptide bond (proteolysis).
in food processing (see for example Ichishima 2000). Micro-organisms can
be modifi ed biotechnologically to over express one specifi c enzyme, leading
to increased purity and higher concentration. Also, enzymes produced
by microbiological fermentation do not encounter diffi culties such as
inconsistent supply—hence price deviation—due to natural shortage or
animal illnesses such as BSE or Foot-and-mouth disease. Microbiological
enzymes by itself are of Kosher and Halal status.
Classifi cation
Proteases are classifi ed based on the following:
(1)
action patterns
; even though all proteases split peptide bonds via
hydrolysis, each is unique in cleaving specifi city and substrate
transformation:
• endoproteases hydrolyze interior peptide bonds in proteins and
protein fractions, liberating protein fragments of reduced size.
The proline specifi c protease of
A. niger
is an example of an
endoprotease (Edens et al. 2005)
• exoproteases hydrolyze terminal peptide bonds in proteins and
peptides; liberating single amino acid units. Exoproteases can be
further classifi ed as:
- aminopeptidases; hydrolysing peptide bonds at the amine group
ends of peptides (-NH2; N-terminal); liberating single amino acid
units. Flavourzyme, an
A. oryzae
fermentation product, contains
an aminopeptidase (Blinkovsky et al. 2000).
