329:(BBI). STI is a large (20,100 daltons), strong inhibitor of trypsin, while BBI is much smaller (8,000 daltons) and inhibits both trypsin and chymotrypsin. Both inhibitors have significant anti-nutritive effects in the body, affecting digestion by hindering protein hydrolysis and activation of other enzymes in the gut. STI is found in much larger concentrations than BBI in soy, however, to achieve the highest nutritional value from soy, both of these inhibitors must be denatured in some way. Whole soybeans have been reported to contain 17–27 mg of trypsin inhibitor per gram.
480:
However, the mechanism is still unknown. The cancers showing positive results for this new development are colon, oral, lung, liver, and esophageal cancers. Further research is still necessary to determine things such as the method of delivery for this natural anti-carcinogen, as well as performing extensive clinical trials in this area.
26:
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While trypsin inhibitors have been widely regarded as anti-nutritive factors in soy, research is currently being done on the inhibitors’ possible anti-carcinogenic characteristics. Some research has shown that protease inhibitors can cause irreversible suppressive effect on carcinogenic cell growth.
431:
The amount of soy inhibitors is directly related to the amount of trypsin it will inhibit, therefore a product with high concentration of soy is likely to produce large values of inhibition. In a rat model, animals were fed either soy protein concentrate or direct concentrate of STI. In both
463:, enabling STI to avoid degradation in the stomach and then inhibit trypsin. Hence STI was engineered into an antibody mimetic called a gastrobody, aiming to address the problems of antibody degradation in the gut following oral delivery. Loops of STI were randomized and selected by
432:
instances, after a week the rats showed a dose-related increase in pancreas weight due to both hyperplasia and hypertrophy. This indicates that long-term consumption of a diet high in soy with strong trypsin inhibitor activity may produce unwanted effects in humans as well.
420:), or continue breaking down proteins. However, if trypsin inhibitors (specifically STI) are present, the majority of trypsin in the cycle of digestion is inactivated and ingested proteins remain whole. Effects of this occurrence include gastric distress, and pancreatic
397:, blocking its active site and instantly forming a highly stable adduct and halting digestion of certain proteins. Trypsin, a serine protease, is responsible for cleaving the polypeptide backbone following
654:
Murzin AG, Lesk AM, Chothia C (January 1992). "beta-Trefoil fold. Patterns of structure and sequence in the Kunitz inhibitors interleukins-1 beta and 1 alpha and fibroblast growth factors".
381:
Despite the structural similarity, STI shows no interleukin-1 bioactivity, presumably as a result of their primary sequence disparities. The active inhibitory site containing the
137:
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A significant amount of research is being done to determine the best method of inhibitor inactivation. The most successful methods found so far include:
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Trypsin inhibitors require a specific three-dimensional structure in order to inactivate trypsin in the body. They bind strongly to
366:(ETI) and the bifunctional proteinase K/alpha-amylase inhibitor from wheat (PK13) have been solved, showing them to share the same
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Onesti S, Brick P, Blow DM (January 1991). "Crystal structure of a Kunitz-type trypsin inhibitor from
Erythrina caffra seeds".
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and undergoes specific proteolysis for activation. Free trypsin is then able to activate other serine proteases, such as
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section. The crystal structures of soybean trypsin inhibitor (STI), trypsin inhibitor DE-3 from the Kaffir tree
321:
Two types of trypsin inhibitors are found in soy: the Kunitz-type soybean trypsin inhibitor (STI, discovered by
849:
775:
771:
145:
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Protease inhibitory activity is decreased by cooking soybeans, leading to low levels in soy products such as
141:
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613:"Effects of antinutritional factors on protein digestibility and amino acid availability in foods"
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712:"Gastrobodies are engineered antibody mimetics resilient to pepsin and hydrochloric acid"
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is located in the loop between beta-strands 4 and 5 in STI and ETI.
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Bassaneze V, Gozzo AJ, Nunes VA, Paiva PB, Araujo MS, Sampaio CA.
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688:, Horton HR, Moran, LA, Scrimgeour KG, Perry MD, Rawn JD, 2006.
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700:, Smith JC, Wilson Fd, Allen PV, Berry DL, 1989. J Appl Toxic.
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Soybean
Trypsin Inhibitors are usually specific for either
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A web/HMMer based tool to study Kunitz protease inhibitors
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Proteins from the Kunitz family contain from 170 to 200
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This article incorporates text from the public domain
758:, Messina M, Barnes S, 1991. J Natl Cancer Institute.
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Rawlings ND, Morton FR, Kok CY, Kong J, Barrett AJ.
408:After a meal, trypsinogen release is stimulated by
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467:for binding to a target of interest (a toxin from
553:Rawlings ND, Tolle DP, Barrett AJ (March 2004).
555:"Evolutionary families of peptidase inhibitors"
356:. The best conserved region is found in their
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493:
389:Action and Consequences of Trypsin Inhibitors
30:Structure of a Kunitz-type trypsin inhibitor.
8:
601:, DiPietro CM, Liener IE, 1989. J Food Sci.
325:and sometimes abbreviated as KTI) and the
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24:
774:at the U.S. National Library of Medicine
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611:Gilani GS, Cockell KA, Sepehr E (2005).
784:"Inhibitor family I3 (Kunitz-P family)"
710:Wicke N, Bedford MR, Howarth M (2021).
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352:residues and one or two intra-chain
436:Inactivation of Trypsin Inhibitors
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809:. Federal University of São Paulo
772:Trypsin+Inhibitor,+Kunitz+Soybean
416:, elastase, and more trypsin (by
287:Kunitz soybean trypsin inhibitor
788:MEROPS - the Protease Database
376:heparin-binding growth factors
19:Trypsin and protease inhibitor
1:
618:Journal of AOAC International
109:Available protein structures:
668:10.1016/0022-2836(92)90668-A
524:10.1016/0022-2836(91)90618-G
424:(proliferation of cells) or
459:STI is highly resistant to
297:seeds which functions as a
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820:
728:10.1038/s42003-021-02487-2
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23:
776:Medical Subject Headings
428:(enlargement of cells).
803:"Kunitz STI inhibitors"
632:10.1093/jaoac/88.3.967
370:structure as those of
469:Clostridium difficile
327:Bowman-Birk inhibitor
450:Addition of Sulfites
571:10.1042/BJ20031825
299:protease inhibitor
845:Antibody mimetics
368:beta trefoil fold
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811:. Retrieved
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716:Commun. Biol
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455:Gastrobodies
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414:chymotrypsin
407:
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361:
347:
331:
323:Moses Kunitz
320:
311:chymotrypsin
286:
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426:hypertrophy
422:hyperplasia
303:Kunitz-type
36:Identifiers
839:Categories
813:2008-12-19
793:2008-12-19
722:(1): 960.
559:Biochem. J
484:References
358:N-terminal
350:amino acid
317:Background
186: ,
121:structures
831:IPR002160
508:;
344:Structure
270:,
264:,
258:,
252:,
246:,
240:,
234:,
228:,
222:,
216:,
210:,
204:,
198:,
192:,
180:,
174:,
79:PDOC00255
67:IPR002160
827:InterPro
746:34381153
641:16001874
589:14705960
540:46210915
447:Freezing
399:arginine
338:soy milk
138:RCSB PDB
62:InterPro
737:8358037
676:1738162
580:1224039
532:1988676
395:trypsin
307:trypsin
291:protein
276:
74:PROSITE
55:PF00197
778:(MeSH)
744:
734:
674:
639:
587:
577:
538:
530:
461:pepsin
403:lysine
295:legume
153:PDBsum
127:
117:
99:SUPFAM
41:Symbol
536:S2CID
95:SCOPe
86:SCOP2
825:and
823:Pfam
742:PMID
672:PMID
637:PMID
585:PMID
528:PMID
505:1tie
444:Heat
374:and
336:and
334:tofu
273:4wbc
267:2wbc
261:2iwt
255:2et2
249:2esu
243:2beb
237:2bea
231:1xg6
225:1wbc
219:1wba
213:1tie
207:1r8n
201:1fn0
195:1fmz
189:1eyl
183:1ba7
177:1avu
171:1ava
146:PDBj
142:PDBe
125:ECOD
115:Pfam
91:1tie
50:Pfam
732:PMC
724:doi
664:doi
660:223
627:doi
575:PMC
567:doi
563:378
520:doi
516:217
501:PDB
471:).
401:or
309:or
165:PDB
133:PDB
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
