[Effect of proteinaceous proteinase inhibitors from potato tubers on the growth and development of phytopathogenic microorganisms].

We studied the effect of two proteins, PSPI-21 and PKSI, on the growth and development of phytopathogenic microorganisms (Phytophthora infestans oomycete and Fusarium culmorum fungus). Both proteins were isolated from potato tubers (Solanum tuberosum L., cv. Istrinskii) and served as inhibitors of serine proteinases. These proteins differed in the ability to inhibit growth of Phytophthora infestans oomycete and Fusarium culmorum fungus. PSPI-21 was the most potent in modulating the growth of oomycete mycelium. PKSI primarily affected the growth of the fungal mycelium. The proteins under study induced complete destruction of oomycete zoospores and partial destruction of fungal macroconidia. Our results suggest that these proteins are involved in the protection of potato plants from phytopathogenic microorganisms.

[Isolation and characteristics of a new trypsin and chymotrypsin inhibitor from potato tubers]. / Vydelenie i kharakteristika novogo ingibitora tripsina i khimotripsina iz klubnei kartofelia.

A novel trypsin and chymotrypsin inhibitor has been isolated from potato (Solanum tuberosum L.) tubers. The isolation procedure included ammonium sulfate precipitation, gel-chromatography on Sephadex G-75 and ion-exchange chromatography on DEAE-cellulose. The inhibitor interacts with trypsin and chymotrypsin at a molar ratio of 1:1. The substrate-dependent dissociation of the enzyme-inhibitor complexes is observed. The inhibitor displays no activity towards subtilisin and pancreatic elastase. The ability of the inhibitor to form a ternary complex containing simultaneously both trypsin and chymotrypsin molecules testifies to the presence of two independent reactive sites for these enzymes.