Kunitz trypsin inhibitors

JOFUKU, K.D., SCHIPPER, R.D., GOLDBERG, R.B., A ffameshift mutation prevents Kunitz trypsin-inhibitor messenger-RNA accumulation in soybean embryos, Plant Cell, 1989,1,427-435. 

Aprotinin is a polypeptide consisting of 58 amino acid residues derived from bovine lung tissues and shows inhibitory activity toward various proteolytic enzymes including chymo-trypsin, kallikrein, plasmin, and trypsin. It was also one of the first enzyme inhibitors used as an auxiliary agent for oral (poly)peptide administration. The co-administration of aprotinin led to an increased bioavailability of peptide and protein drugs [5,44,45], The Bowman-Birk inhibitor (71 amino acids, 8 kDa) and the Kunitz trypsin inhibitor (184 amino acids, 21 kDa) belong to the soybean trypsin inhibitors. Both are known to inhibit trypsin, chymotrypsin, and elastase, whereas carboxypeptidase A and B cannot be inhibited [7,46],... 

Zhang, Y. and Parsons, C.M. (1993) Effect of extrusion and expelling on the nutritional quality of conventional and kunitz trypsin inhibitor-free soybeans. Poultry Science 72, 2299-2308. 

Furthermore, the soybean hull proteins Gly m 1 and Gly m 2, the soybean profilin Gly m 3, and Gly m 4 (also called Kunitz-trypsin inhibitor, formerly SAM 22) are officially accepted as soybean allergens according to the criteria of the International... 

In vitro IgE-binding studies performed with blood of patients suffering from soy allergy reported sensitivity to glycinin and Gly m 1 in over 90%, to Kunitz-trypsin inhibitor in 86%, and to prohlin (Gly m 3) in 69% of all investigated cases. A number of reactivities to other not yet completely characterized moieties between 5 and 20kDa have also been described (NDA Opinion 2004). 

Roychaudhuri, R., Sarath, G., Zeece, M., and Markwell, J. 2004. Stability of the allergenic soybean Kunitz trypsin inhibitor. Biochim Biophys Acta 1699 207-212. 

Polypeptides Aprotinin (Kimura et al. 1996, Saffran et al. 1988, Yamamoto et al. 1994), Bowman-Birk inhibitor, Kunitz trypsin inhibitor, chicken egg white trypsin inhibitor (Reseland et al. 1996, Ushirogawa 1992), chicken ovoinhibitor (Scott et al. 1987), human pancreatic trypsin... 

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

Zhang et al. (18) studied the effect of extrusion and expelling on the nutritional quahty of conventional and Kunitz trypsin inhibitor-free soybeans in chicken. Their results indicated that increasing the extrusion temperature of conventional soybeans (CSB) to 138°C and 154°C significantly increased the TME compared with CSB extruded at 104°C or 121°C (3815kcal/kg DM, 3936 kcal/kg DM vs. 3665 kcal/kg DM, 3678 kcal/kg DM, respectively). Extruding Kunitz trypsin inhibitor-free soybeans at 104°C, 121°C, and 138°C resulted to similar TME as that of CSB extruded at 138°C and 154°C. 

The soy storage proteins (glycinin /3-conglycinin) and an antigenic soy protein (of low molecular mass) were degraded by the proteolytic process and an apparent loss of antigenicity was observed. However, the proteolytic effect on soy lectin and Kunitz trypsin inhibitor was obviously lost, although some minor decrease in immunoreactivity could be observed. 

The 2S fraction of soybean seeds contains the trypsin inhibitors as well as other smaller MW proteins (<25 kD) such as cytochrome c. The two best characterized trypsin inhibitors in soybeans are the Kunitz trypsin inhibitor (KTI) and the tryp-sin-chymotrypsin double-headed Bowman Birk inhibitor (BBI). Apparently several... 

TIs are protease-inhibiting factors that bind the protease enzymes to decrease their catalytic power. The two predominant protease inhibitors are Kunitz trypsin inhibitor and Bowman-Birk inhibitor (BBI), and they are both protein in nature. 

Kunitz trypsin inhibitor has a molecular weight between 20 and 25 kDa. It consists of 181 amino acid residues and two disulfide bonds (Liu, 1999a). BBI is a pro-... 

Inagaki, K. H. Kobayashi R. Yoshida. Y. Kanada Y. Fukuda T. Yagyu T. Kondo N. Kurita T. Kitanaka Y. Yamada Y. Sakamoto M. Suzuki N. Kanayama T. Terao. Suppression of urokinase expression and invasion by a soybean Kunitz trypsin inhibitor are mediated through inhibition of Src-dependent signaling pathways./. Biol. Chem. 2005, 280, 31428—31437. 

Kobayashi, H. M. Suzuki N. Kanayama T.A. Terao. Soybean Kunitz trypsin inhibitor suppresses ovarian cancer cell invasion by blocking urokinase upregulation. Clin. Exp. Metastasis, 2004b, 21 159-166. 

HARUTA, M., MAJOR, I.T., CHRISTOPHER, M.E., PATTON, J.J., CONSTABEL, C.P., A Kunitz trypsin inhibitor gene family from trembling aspen Populus tremuloides Michx.) cloning, functional expression, and induction by wounding and herbivory. Plant Molec. Biol, 2001,46, 347-359. 

MIRANDA, M., CHRISTOPHER, M.E., CONSTABEL, C.P., The variable nature of herbivore defense evidence for a rapidly diverging Kunitz trypsin inhibitor gene in Populus, in Plant Adaptation Molecular Genetics and Ecology (Q.C.B. Cronk, J. Whitton, R.H. Ree, I.E.P. Taylor, eds.), NRC Press, Ottawa. 2004, pp. 153-158... 

McManus, M.T. and Burgess, E.P.J. (1999). Expression of the soybean (Kunitz) trypsin inhibitor in transgenic tobacco Effects on feeding larvae of Spodoptera litura. Transgenic Res. 8, 383-395. 

VODKIN, L.O., Isolation and characterization of messenger RNAs for seed lectin and Kunitz trypsin inhibitor in soybeans. Plant Physiol, 1981,68,766-771. 

Trypsin inhibitors (TI) are present in many plant foods, but soybeans are one of the most widely consumed crops containing these antinutrients. TI prevent protein digestion and eventually consumption can lead to pancreatic hypertrophy or poor growth. Higher extrusion temperatures (138—154°C) were required for conventional soybeans to achieve the same nutritional quality as extruded Kunitz trypsin inhibitor-free beans processed at 121—138°C (Zhang et ai, 1993). Soybeans extruded at these temperatures were comparable to commercial solvent-extracted soy meal. Urease index decreased and chick growth performance increased as extrusion temperature was raised. 

Three inhibitors from non-food sources are included in Table II. The basic (Kunitz) trypsin inhibitor from bovine pancreas (BPTI) is a small protein that has been used extensively in protein structure studies. At neutral or acid pH, it denatures near 100°C. From the ratio of calorimetric to van t Hoff (effective) enthalpies, Privalov... 

Oxidation of Met residues has significantly affected biological activity in some instances (subtilisin, E. colt ribosomal protein L12), but has shown no effect in others (ribonuclease, Kunitz trypsin inhibitor). As is the case with degradation at Asx, the rate of oxidation at select residues within a protein is dependent upon higher-order structure, presumably because of solvent inaccessibility or steric hindrance. Howevei unlike the case of Asx degradation, there are no primary sequence or other structural motifs found to strongly correlate with oxidation of Met. Other amino add residues susceptible to oxidation are Cys, His, Trp, and Tyr. 

Soybeans contain compounds that impair activity of enzymes trypsin, chymotrypsin, carboxypeptidase, elastase, and a-amylase. The presence of enzyme inhibitors, Bowman-Birk inhibitor (BBI) (an inhibitor of chymotrypsin and trypsin) and Kunitz trypsin inhibitor (KTI), in unheated soybeans hinders the activity of protease enzymes trypsin and... 

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