Sweet potato (Ipomoea batatas (L.) Lam) trypsin inhibitors, the major root storage proteins, inhibit one endogenous serine protease activity

Wen C. Hou, Yaw Huei Lin

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8 Citations (Scopus)

Abstract

Proteases were purified successively by trypsin-Sepharose 4B, sweet potato (Ipomoea batatas [L.] Lam) trypsin inhibitor (SPTI)-Sepharose 4B, benzamidine-Sepharose 6B, and arginine-Sepharose 4B affinity columns from crude extracts of SP dormant roots. One of them, Arg-1, was specific to the substrate benzoyl-arginine-p-nitroanilide, with an optimal pH 8.0. Arg-1 migrated as a single band of 20 kDa in SDS-PAGE, detected by activity staining. The activity was completely inhibited by SPTI in a dose-dependent manner. The activity was inhibited by aprotinin and soybean TI, but not by E-64, pepstatin A or EDTA. This suggested that Arg-1 was a serine type protease, inhibited endogenously by SPTI. Denatured SPTI could be degraded by Arg-1 in vitro. The physiological role of SPTI in the regulation of Arg-1 activity was discussed.

Original languageEnglish
Pages (from-to)733-739
Number of pages7
JournalPlant Science
Volume163
Issue number4
DOIs
Publication statusPublished - Oct 1 2002

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Keywords

  • Physiological function
  • Regulation
  • Serine protease
  • Sweet potato
  • Trypsin inhibitor

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry
  • Biotechnology

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