Plant Kunitz serine protease inhibitor

Plant Kunitz serine protease inhibitor proteins... 

Table 12. Plant Kunitz serine protease inhibitor proteins For details see the legend to Table 4.

Solanum (potato) Kunitz PEPs inhibit the aspartic protease cathepsin D as well as trypsin [125-134] and potato cysteine protease inhibitor (PCPI) inhibits a variety of cysteine proteases [185-188]. The crystal structures of soybean trypsin inhibitor (STI) [362, 368] and of Erythrina trypsin inhibitor (ETI) [350] have been determined. The structure of this type of plant Kunitz serine PIP involves a [3-barrel formed by 6 loop-linked antiparallel [3-strands with a lid formed by 6 further loop-linked antiparallel [3-strands. The scissile bond is located within a loop that extends out from the surface of the [3-barrel [350, 362, 368]. 

Based on their sequence homology, disulfide connectivity, and cysteine location within the sequence and chemistry of the reactive site. Pis can be assigned to distinct families, as classified by Laskowski and Kato. Kunitz-type, Bowman—Birk-type, Potato type I and type II, and squash inhibitors are members of these families shown in Table 3. For inhibitors not falling into these classifications more families have been proposed. Pis can also be classified by their target/mode of action. Plants have been found to express Pis that target serine proteinases, cysteine proteinases, aspartic proteinases, and metallo-proteinases. Serine and cysteine protease inhibitors are the best-studied PIs. ... 

Inhibitors of proteolytic enzymes may play an important role in plant protection not only from harmful insects, but also other pests nematodes, the nematodes. Many nematodes are parasitic on plants and cause significant damage to agricultural production. In the gut of nematodes contains active cysteine and serine proteases, including chymotrypsin and kallikrein is similar. It is interesting that when infected with worms, among transcripts of tomato were found proteins related to the family of Kunitz inhibitor (SBH) (Valueva Mosolov, 2002 Schroeder et al., 1995). 

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