Aspergillopepsin II explained

Aspergilloglutamic peptidase
Ec Number:3.4.23.19
Cas Number:9025-49-4
Width:240px

Aspergilloglutamic peptidase, also called aspergillopepsin II (proctase A, Aspergillus niger acid proteinase A, Aspergillus niger var. macrosporus aspartic proteinase) is a proteolytic enzyme.[1] [2] The enzyme was previously thought be an aspartic protease, but it was later shown to be a glutamic protease with a catalytic Glu residue at the active site, and was therefore renamed aspergilloglutamic peptidase.[3]

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.[4]

This enzyme catalyses the following chemical reaction

Preferential cleavage in B chain of insulin: Asn3-Gln, Gly13-Ala, Tyr26-Thr

This enzyme is isolated from Aspergillus niger var. macrosporus.

Notes and References

  1. The structure and function of acid proteases. VI. Effects of acid protease-specific inhibitors on the acid proteases from Aspergillus niger var. macrosporus . Chang, W.J. . Horiuchi, S. . Takahashi, K. . Yamasaki, M. . Yamada, Y. . J. Biochem. . 1976 . 80 . 975–981 . 12156.
  2. Specificity of acid proteinase A from Aspergillus niger var. macrosporus towards B-chain of performic acid oxidized bovine insulin . Iio, K. . Yamasaki, M. . Biochim. Biophys. Acta . 1976 . 429 . 912–924 . 1268233 . 10.1016/0005-2744(76)90336-3.
  3. Structure and function studies on enzymes with a catalytic carboxyl group(s): from ribonuclease T1 to carboxyl peptidases. Takahashi K . Proc Jpn Acad Ser B Phys Biol Sci . 2013. 89. 6. 201–25 . 10.2183/pjab.89.201 . 23759941 . 3749792.
  4. Journal of Biochemistry . 2012 . 152. 1. 45–52 . 10.1093/jb/mvs050 . The crystal structure of an intermediate dimer of aspergilloglutamic peptidase that mimics the enzyme-activation product complex produced upon autoproteolysis . Sasaki H, Kubota K, Lee WC, Ohtsuka J, Kojima M, Iwata S, Nakagawa A, Takahashi K, Tanokura M . 22569035.

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