Protease inhibitors Kunitz

Bauw, G.,Nielsen, H. V,Emmersen, J.,Nielsen, K., Jorgensen, M., Welinder,K. (2006). Patatins,Kunitz protease inhibitors and other major proteins in tuber of potato cv. Kuras. FEES J., 273, 3569-3584. 

KATI and KATII, kynurenine aminotransferases I and II KPI, Kunitz protease inhibitor K-R, kainate receptor KTI, Kunitz trypsin inhibitor... 

Feeding rats raw soybeans or pure soybean inhibitor of the digestive enzymes chymotrypsin and trypsin, the so-called Bowman-Birk and Kunitz protease inhibitors, induce hypertrophy and hypersecretion of chymotrypsin and trypsin by the pancreas. Raw soy flour diets also potentiate the carcinogenicity of azaserine and nitrosamines in rats. A so-called biofeedback mechanism has been postulated to explain these consequences of soybean nutrition 4-17). 

KU BPTI/Kunitz family of serine protease inhibitors E(M) 0(0) 42(141) 1AAL... 

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. ... 

Kunitz-type protease inhibitors usually are large polypeptides of more than 120 amino acids and will not be discussed here, based on the focus of the review being peptides of fewer than 100 amino acids in length. Searches of publicly available databases yield a few short sequences, which are fragments from larger proteins that have only been partially sequenced. 

Pouvreau, L., Gruppen, H., van Koningsveld, G. A., van den Broek, L. A. M., Voragen, A. G. J. (2003). The most abundant protease inhibitor in potato tuber (cv. Elkana) is a serine protease inhibitor from the Kunitz family. J. Agric. Food Chem., 51, 5001-5005. 

Protease nexin 2 is identical to the secreted form of the amyloid precursor protein containing the Kunitz-type serine protease inhibitor domain (128,129), Protease nexin 2 circulates in blood stored as a platelet a-granule protein, which is secreted upon platelet activation (127). Protease nexin 2 inhibits trypsin- and chymotrypsin-like serine proteases and is also a potent inhibitor of factor Xla (126,127,128). Its location in platelets and its ability to inhibit factor Xla suggests a role in regulating blood coagulation for protease nexin 2. 

SPINT2 Serine protease inhibitor, kunitz type 2... 

The Bowman-Birk type protease inhibitors represent a class of low molecular weight, cysteine-rich proteins found in legume seeds (.10). The major Bowman-Birk inhibitor in soybean seeds is a double-headed protein capable of blocking the activity of both trypsin and chymotrypsin. This protein represents approximately 4% of the total protein in soybean seeds (1J ). In contrast to the soybean trypsin inhibitor (Kunitz), the "double-headed inhibitor (referred to as BB) is typical of protease inhibitors present in a large number of legume seeds for example, peanuts (12) chick peas (33)5 kidney beans (3JO adzuki beans (33) lima beans (16). 

A variety of aspartic protease inhibitor (API) proteins have been resolved from plants [122-135] of which the best characterized at the gene and protein level are those from Solanum tuberosum (potato) (Solanaceae) [124-134] (Table 4). The potato aspartic protease inhibitor proteins are typically about 190 residues (about 20 kDa), have 3 disulphide bridges, are homologous to the soybean trypsin inhibitor (Kunitz) family Pis [133] and can also inhibit trypsin [124-134] (Table 4). 

Solatium tuberosum (Solanaceae) [tuber] Potato Cysteine Protease Inhibitors (PCPIs) (20-25 kDa Kunitz PI homologues - for details see Table 12 ) Cysteine proteases (e.g. Papain, Cathepsins B, H L) - for details see Table 12 [185- 188]... 

Plant Kunitz serine protease inhibitor proteins... 

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]. 

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