Aspergilloglutamic peptidase, also called aspergillopepsin II (, ''proctase A'', '' Aspergillus niger acid proteinase A'', ''Aspergillus niger var. macrosporus aspartic proteinase'') is a
proteolytic
Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called protease ...
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
. The enzyme was previously thought be an
aspartic protease
Aspartic proteases are a catalytic type of protease enzymes that use an activated water molecule bound to one or more aspartate residues for catalysis of their peptide substrates. In general, they have two highly conserved aspartates in the activ ...
, but it was later shown to be a
glutamic protease
Glutamic proteases are a group of proteolytic enzymes containing a glutamic acid residue within the active site. This type of protease was first described in 2004 and became the sixth catalytic type of protease. Members of this group of protease h ...
with a catalytic Glu residue at the active site, and was therefore renamed aspergilloglutamic peptidase.
Determination of its molecular structure showed it to be a unique two-chain enzyme with a light chain and a heavy chain bound non-covalently with each other. The C-terminal region of the light chain of one molecule binds to the active site cleft of another molecule in the manner of a substrate.
This enzyme
catalyses the following
chemical reaction
A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...
: Preferential cleavage in B chain of
insulin: Asn
3-Gln, Gly1
3-Ala, Tyr
26-Thr
This enzyme is isolated from ''
Aspergillus niger
''Aspergillus niger'' is a mold classified within the ''Nigri'' section of the ''Aspergillus'' genus. The ''Aspergillus'' genus consists of common molds found throughout the environment within soil and water, on vegetation, in fecal matter, on de ...
var. macrosporus''.
References
External links
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EC 3.4.23