Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla
Plant peptidase inhibitors play essential roles in the defense systems of plants. A trypsin inhibitor (PHTI) with a molecular mass of 20.5 kDa was isolated from the fresh roots of the medicinal herb, Pseudostellaria heterophylla. The purification process involved ammonium sulfate precipitation, gel...
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doaj-33d7458dc7974167b51fb23ffce8d8862020-11-24T21:48:27ZengMDPI AGMolecules1420-30492018-09-01239238810.3390/molecules23092388molecules23092388Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophyllaXixi Cai0Xiaoli Xie1Nanyan Fu2Shaoyun Wang3The Key Lab of Analysis and Detection Technology for Food Safety of the MOE, College of Chemistry, Fuzhou University, Fuzhou 350108, ChinaInstitute of Food and Marine Bio-Resources, College of Biological Science and Technology, Fuzhou University, Fuzhou 350108, ChinaThe Key Lab of Analysis and Detection Technology for Food Safety of the MOE, College of Chemistry, Fuzhou University, Fuzhou 350108, ChinaInstitute of Food and Marine Bio-Resources, College of Biological Science and Technology, Fuzhou University, Fuzhou 350108, ChinaPlant peptidase inhibitors play essential roles in the defense systems of plants. A trypsin inhibitor (PHTI) with a molecular mass of 20.5 kDa was isolated from the fresh roots of the medicinal herb, Pseudostellaria heterophylla. The purification process involved ammonium sulfate precipitation, gel filtration chromatography on Sephadex G50, and ion-exchange chromatography on DEAE 650M. The PHTI contained 3.7% α-helix, 42.1% β-sheets, 21.2% β-turns, and 33% disordered structures, which showed similarity with several Kunitz-type trypsin inhibitors. Inhibition kinetic studies indicated that PHTI was a competitive inhibitor, with a Ki value of 3.01 × 10−9 M, indicating a high affinity to trypsin. The PHTI exhibited considerable stability over a broad range of pH (2–10) and temperatures (20–70 °C); however, metal ions, including Fe3+, Ba2+, Mn2+, and Al3+, could inactivate PHTI to different degrees. Results of fluorescence spectroscopy and circular dichroism showed that Fe3+ could bind to TI with an association constant of 2.75 × 105 M−1 to form a 1:1 complex, inducing conformation changes and inactivation of PHTI. In addition, PHTI could inhibit the growth of the phytopathogens, Colletotrichum gloeosporioides and Fusarium oxysporum, through disruption of the cell membrane integrity. The present study extended research on Pseudostellaria heterophylla proteins and makes PHTI an exploitable candidate as an antifungal protein for further investigation.http://www.mdpi.com/1420-3049/23/9/2388trypsin inhibitorPseudostellaria heterophyllafluorescence spectroscopycircular dichroismantifungal |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Xixi Cai Xiaoli Xie Nanyan Fu Shaoyun Wang |
spellingShingle |
Xixi Cai Xiaoli Xie Nanyan Fu Shaoyun Wang Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla Molecules trypsin inhibitor Pseudostellaria heterophylla fluorescence spectroscopy circular dichroism antifungal |
author_facet |
Xixi Cai Xiaoli Xie Nanyan Fu Shaoyun Wang |
author_sort |
Xixi Cai |
title |
Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla |
title_short |
Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla |
title_full |
Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla |
title_fullStr |
Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla |
title_full_unstemmed |
Physico-Chemical and Antifungal Properties of a Trypsin Inhibitor from the Roots of Pseudostellaria heterophylla |
title_sort |
physico-chemical and antifungal properties of a trypsin inhibitor from the roots of pseudostellaria heterophylla |
publisher |
MDPI AG |
series |
Molecules |
issn |
1420-3049 |
publishDate |
2018-09-01 |
description |
Plant peptidase inhibitors play essential roles in the defense systems of plants. A trypsin inhibitor (PHTI) with a molecular mass of 20.5 kDa was isolated from the fresh roots of the medicinal herb, Pseudostellaria heterophylla. The purification process involved ammonium sulfate precipitation, gel filtration chromatography on Sephadex G50, and ion-exchange chromatography on DEAE 650M. The PHTI contained 3.7% α-helix, 42.1% β-sheets, 21.2% β-turns, and 33% disordered structures, which showed similarity with several Kunitz-type trypsin inhibitors. Inhibition kinetic studies indicated that PHTI was a competitive inhibitor, with a Ki value of 3.01 × 10−9 M, indicating a high affinity to trypsin. The PHTI exhibited considerable stability over a broad range of pH (2–10) and temperatures (20–70 °C); however, metal ions, including Fe3+, Ba2+, Mn2+, and Al3+, could inactivate PHTI to different degrees. Results of fluorescence spectroscopy and circular dichroism showed that Fe3+ could bind to TI with an association constant of 2.75 × 105 M−1 to form a 1:1 complex, inducing conformation changes and inactivation of PHTI. In addition, PHTI could inhibit the growth of the phytopathogens, Colletotrichum gloeosporioides and Fusarium oxysporum, through disruption of the cell membrane integrity. The present study extended research on Pseudostellaria heterophylla proteins and makes PHTI an exploitable candidate as an antifungal protein for further investigation. |
topic |
trypsin inhibitor Pseudostellaria heterophylla fluorescence spectroscopy circular dichroism antifungal |
url |
http://www.mdpi.com/1420-3049/23/9/2388 |
work_keys_str_mv |
AT xixicai physicochemicalandantifungalpropertiesofatrypsininhibitorfromtherootsofpseudostellariaheterophylla AT xiaolixie physicochemicalandantifungalpropertiesofatrypsininhibitorfromtherootsofpseudostellariaheterophylla AT nanyanfu physicochemicalandantifungalpropertiesofatrypsininhibitorfromtherootsofpseudostellariaheterophylla AT shaoyunwang physicochemicalandantifungalpropertiesofatrypsininhibitorfromtherootsofpseudostellariaheterophylla |
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