Lima bean trypsin inhibitor

An additional emission band near 350 nm has been observed for lima bean trypsin inhibitor (LBTI).(173) The authors discussed both the possibility of contamination by tryptophan and excited-state tyrosinate formation. Since this 350-nm emission has a tyrosine-like excitation spectrum that is slightly shifted compared to that of the major 302-nm emission, it is also possible that the tyrosine residue in a fraction of the LBTI molecules could be hydrogen bonded. This model is supported by the observations that the phenol side chain is shielded from solvent and has an anomalously high pKa. 

Enzyme Bovi ne pancreati c trypsin inhibitor Lima bean trypsin inhibitor Soybean trypsin inhibitor Ovomucoi d... 

G proteins are located in different compartments within the cell (Nurnberg and Ahnert-Hilger, 1996). Although most G proteins are found attached to the plasma membrane and intracellular membranes, some are also located within the cytoplasm (Rudolph et al., 1989). Therefore, G proteins in preparations of disrupted cells, or in cell and tissue extracts are also subject to pertussis toxin-mediated ADP-ribosylation. In this case, precautions have to be taken to prevent proteolysis, and protease inhibitors should be included in the buffer (aprotonin, p-aminobenzamidine, leupeptin, phenylmethylsul-fonyl fluoride, or soybean or lima bean trypsin inhibitors) (Carty, 1994). 

The major plasma inhibitor of Factor XIa is Uj-antitrypsin while antithrombin III, in the presence or absence of heparin, plays a minor role in controlling this enzyme (S5). Interestingly, plant inhibitors like soybean, com, and lima bean trypsin inhibitors are able to block Factor Xlla and kallikrein but only mildly inhibit Factor XI. Thus, one can use these agents to minimize cross-reactivity in an indirect s)mthetic substrate assay for Factor XIa. 

Despite the great numbers of protease and amylase inhibitors found in biological materials, more recent data indicate there is some homology among the inhibitors Comparison of the complete amino acid sequences of lima bean trypsin inhibitors I and IV shows that the two isolnhibltors differ only in that inhibitor IV contains an eight amino acid N-terminal segment and an additional two Asn residues at the C-terminal end not present in inhibitor I (75) ... 

There is great homology between the Bowman-Birk soybean trypsin inhibitor (89), lima bean trypsin inhibitor IV (75) and the Great Northern trypsin inhibitor II (90) as shown in Table VIII The tryptic peptide maps of Great Northern isoinhibitors I and mb were very similar while isoinhibitors I and II had no peptides in common (15) ... 

Table VIII. Amino Acid Sequence Homology Among the Bowman-Birk Soybean Trypsin Inhibitor (BB 89)> Lima Bean Trypsin Inhibitor IV (LB 75) and Great Northern Bean Trypsin Inhibitor II (GB 90)...

XII Hageman factor The first factor in the intrinsic pathway. A/, 74000 (bovine), 76000 (human). Single chain glycoprotein. Activated by plasmin, kallikrein and XII,. Inhibited by antithrombin III (inhibition accelerated by heparin). Cl esterase inhibitor and lima bean trypsin inhibitor. Activation of XII initiated by contact with abnormal surfaces. 

X.-Y. Liu, K. O. Cottrell, and T. M. Nordlund, Spectroscopy and fluorescence quenching of tyrosine in lima bean trypsin/chymotrypsin inhibitor and model peptides, Photochem. 

Figure 1. Thermal denaturation of selected proteinase inhibitors at pH 6.7 in 0.05 M KCl, 0.02 M CaCl . Inhibitors BPTI, bovine pancreatic trypsin inhibitor (Kunitz) PI-I and PI-II, proteinase inhibitors I and II from potato LBI, lima bean protease inhibitor 01, chicken ovoinhibitor. Heating rate, 10 C/min.

Zahniey, J. C. (1980). Independent heat stabilization of proteases associated with multi headed Inhibitors. Complexes of chymotrypsin, subtil 1 sin and trypsin with chicken ovoinhibitor and with lima bean protease Inhibitor. Blochim. Blophys. 

Aletor, V.A. and B.L. Fetuga. 1988. The interactive effects of lima bean (Phaseolus lunatus) trypsin inhibitor, hemagglutinin and cyanide on some hepatic dehydrogenases, ornithine carbamoyltransferase and intestinal disaccharidases in weanling rats. Veterin. Human Toxicol. 30 540-544. 

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). 

Plant - Inhibitors derived from plant sources include the black bean or soybean inhibitors (Kunltz and Bowman-Birk types),34-57 lima bean inhibitor, 38 and chickpea inhibitor.39 These are all unusual double-headed polypeptides, with two Independent reactive sites, capable of interacting with both trypsin and chymotrypsin.60-63 They also are inhibitors of granulocyte elastase and cathepsin... 

Snail epidermis contains at least six trypsin-kallikrein inhibitors with molecular weights ranging from 6431 to 6591 (70-72). The soybean contains two basic types of protease inhibitors, the Kunitz inhibitor of 21,500 daltons (73) and the Bowman-Birk inhibitor of 7975 daltons (74). The two are quite different proteins as shown in Figure 6. The Great Northern bean (Phaseolus vulgaris) has at least three trypsin isoinhibitors ranging in molecular weight from 8086 to 8884 (15). There are four and possibly six isoinhibitors of trypsin in lima bean (Phaseolus lunatus)(75). 

Figure 2. Effect of pH and N-acetylcysteine (NAC) on trypsin inhibitory activity of lima bean inhibitor at 45 C. Upper plot, no NAC lower plot, with NAC.

Fraenkel-Conrat, H., Bean, R. C., Ducay, E. D., and Olcott, H. S. (1952). Isolation and characterization of a trypsin inhibitor from lima beans. Arch. Biochem. Biophys. 37, 393-407. 

Trypsin Lys-X Adzuki bean (API II) Chickpea Garden bean (GBI I) Lima bean (LBIIV) Soybean (BBI) Wisteria (inhibitor II)... 

Trypsin inhibitor (from lima bean) (from soybean) J... 

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