Parent Class:

EC-Numbers → 3 -- Hydrolases → 3.4 -- Acting on peptide bonds (peptide hydrolases) → 3.4.23 -- Aspartic endopeptidases

Synonyms: proteinase A, proctase A, Aspergillus niger var. macrosporus aspartic proteinase

Unification Links: BRENDA:3.4.23.19, ENZYME:3.4.23.19, IUBMB-ExplorEnz:3.4.23.19

Reaction:
protein + H₂O → 2 peptide + 2 H⁺

Summary:
This enzyme catalyzes preferential cleavage in B chain of insulin : Asn³-|-Gln, Gly¹³-|-Ala, Tyr²⁶-|-Thr.

Isolated from Aspergilus niger var.macrosporus, distinct from proteinase B (see aspergillopepsin I) in specificity and insensitivity to pepstatin. In peptidase family A4 (scytalidopepsin B family). Formerly included in EC 3.4.23.6.

Citations: [Chang76, Iio76]

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References

Chang76: Chang WJ, Horiuchi S, Takahashi K, Yamasaki M, Yamada Y (1976). "The structure and function of acid proteases. VI. Effects of acid protease-specific inhibitors on the acid proteases from Aspergillus niger var. macrosporus." J Biochem 80(5);975-81. PMID: 12156

Iio76: Iio K, Yamasaki M (1976). "Specificity of acid proteinase A from Aspergillus niger var. macrosporus towards B-chain of performic acid oxidized bovine insulin." Biochim Biophys Acta 429(3);912-24. PMID: 1268233

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 46(D1):D633-D639 2018
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