Primary structures of two low molecular weight proteinase inhibitors from potatoes

Abstract

The amino acid sequences of two low molecular weight proteinase inhibitors from Russet Burbank potatoes have been determined. One of these, a chymotrypsin inhibitor, is a peptide of 52 amino acid residues, while the second inhibitor, which is specific for trypsin, contains 51 amino acid residues. These peptides are highly homologous, differing at only nine positions. At position 38, the chymotrypsin inhibitor possesses leucine and the trypsin inhibitor an arginine. This difference probably represents the P1 sites, which are consistent with the respective specificities of the two inhibitors. The inhibitors are also homologous with potato inhibitor II and with an inhibitor previously isolated from eggplants.

Posttranslational Modification of an Isoinhibitor from the Potato Proteinase Inhibitor II Gene Family in Transgenic Tobacco Yields a Peptide with Homology to Potato Chymotrypsin Inhibitor I

“…The boxed regions denote sequences that have been identified in this study (as shown in A). C, The published sequences of PCI-I (from B), TTI-#1 (from Pearce et al, 1993), and PTI-I (from Hass et al, 1982). The regions underlined denote sequences within PCI-I that have been identified in this study (as shown in A), and the arrows denote sequence differences within these regions between PCI-I and TTI-#l.…”

“…3D). 6, The published amino acid sequences of PPI-II, designated as PPI-II T (from Thornburg et a!., 1987), PPI-II K (from Keil et al, 1986), and PCI-I (modified from Hass et al, 1982, to accommodate the N-terminal Arg). The boxed regions denote sequences that have been identified in this study (as shown in A).…”

Structure and induction pattern of a novel proteinase inhibitor class II gene of tobacco

“…PI [ 1 ]). These deduced sequences were arranged such as to obtain a maximum alignment with the sequences of tobacco trypsin inhibitor (TTI [ 17], eggplant trypsin inhibitor (EP [20]), potato trypsin inhibitor (PTI [9]) and potato chymotrypsin inhibitor (PCI [9]). The three domains with putative reactive sites present in the tobacco PI-II protein are indicated.…”

Phage display of a double-headed proteinase inhibitor: Analysis of the binding domains of potato proteinase inhibitor II

“…Indeed, inactivation of only domain II strongly reduced binding, confirming that domain II was responsible for most of the actMty against trypsin as well as chymotrypsin. The dual specificity of domain II for trypsin and chymotrypsin was unexpected, because highly homologous single domain PI2 proteins from eggplant and potato, lacking 24 N-terminal and 47 C-terminal residues, but with Arg-62 at the P~-position, were found to be specific for trypsin only [12,25]. In contrast, the P1 residue of domain I did determine the specificity.…”