Primary structure of aspergillopepsin I deduced from nucleotide sequence of the gene and aspartic acid-76 is an essential active site of the enzyme for trypsinogen activation

Takahiro Shintani, Eiji Ichishima

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

The coding region of the aspergillopepsin I (EC 3.4.23.18) gene occupies 1340 base pairs of the genomic DNA and is separated into four exons by three intros. The predicted amino-acid sequence of aspergillopepsin I consists of 325 residues and is 32% and 27% homologous with those of human pepsin and calf chymosin. The cDNA of the gene prepared from mRNA has been cloned and expressed in yeast cells. To identify the residue of the substrate binding pocket in determining the specificity of aspergillopepsin I towards basic substrates, this residue was replaced with a serine residue by site-directed mutagenesis. The mutation is a single amino-acid change, Asp-76 converted to Ser-D76S, in the enzyme. The striking feature of this is that only the trypsinogen activating activity was destroyed. We therefore concluded that Asp-76 is the binding site towards basic substrates.

Original languageEnglish
Pages (from-to)257-264
Number of pages8
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume1204
Issue number2
DOIs
Publication statusPublished - 1994 Feb 16

Keywords

  • (Aspergillus)
  • Aspartic proteinase
  • Aspergillopepsin I
  • Specificity
  • Trypsinogen activation

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology

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