Coix lacryma-jobi chymotrypsin inhibitor displays antifungal activity

• Published in: Pesticide biochemistry and physiology 2019-10, Vol.160, p.49-57
• Main Authors: Ruan, Jing-jun, Weng, Wen-feng, Yan, Jun, Zhou, Yue-xia, Chen, Hui, Ren, Ming-jian, Cheng, Jian-ping
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Antifungal Agents - chemistry; Antifungal Agents - pharmacology; Chymotrypsin - antagonists & inhibitors; Chymotrypsin inhibitor; Coix - chemistry; Coix - embryology; Coix lacryma-jobi L; Hydrogen-Ion Concentration; Plant-pathogenic fungus; Purification; Seeds - chemistry; Sequence analysis; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Trypsin Inhibitors - chemistry; Trypsin Inhibitors - pharmacology
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2019.06.016

A novel chymotrypsin inhibitor, named ClCI, was purified from coix seed (Coix lacryma-jobi L.) by aqueous two-phase extraction, chymotrypsin–Sepharose 4B affinity chromatography and centrifugal ultrafiltration. ClCI was a 7.9 kDa competitive inhibitor with pI 6.54. The inhibition constants (Ki) for bovine pancreatic chymotrypsin and bacterial subtilisin were 1.27 × 10−10 M and 1.57 × 10−9 M respectively. ClCI had no inhibitory activity against bovine trypsin and porcine elastase. ClCI had wide pH stability and good heat resistance. It can maintain >90% inhibition activity against chymotrypsin at 20–80 °C for 1 h. The primary structure of ClCI was highly similar (57%–92%) to those of several inhibitors belonging to the Gramineae crop potato protease inhibitor- I superfamily and showed the typical sequence motif of the protease inhibitor of the seed storage protein group. ClCI (12.5 mg) inhibited mycelial growth of the phytopathogenic fungi Mycosphaerella melonis, Helminthosporium turcicum, Alternaria solani, Phytophthora capsici, Isariopsis griseola, and Colletotrichum gloeosporioides, and caused 89% inhibition of the proteases from spore germination of plant-pathogenic fungi. The results of the present study indicate that ClCI had biotechnological potential as an alternative agent to combat the important phytopathogenic fungi. [Display omitted] •A novel ClTI (Coix lacryma-jobi L. trypsin inhibitor) was identified and characterized.•ClTI is a member of the Gramineae crop potato inhibitor superfamily.•ClTI inhibited the mycelium growth and spore germination of the phytopatogenic fungus.