Composition trypsin inhibitors from

The trypsin inhibitors from several different varieties of Phaseolus vulgaris (common bean) are quite variable in amino acid composition (Figure 5). ASN, SER and 1/2CYS are found in the largest amounts in most of the inhibitors. MET and TRP are quite low in all the inhibitors and absent in a substantial number of them. PRO is present in larger amounts than in most proteins. 

The exact form in which non-crosslinked elastin is secreted from smooth muscle cells is yet to be clearly defined. Foster et al. (36) have suggested that a non-cross linked elastin (pro-elastin) is secreted from smooth muscle cells in a form that is approximately 120,000 to 140,000 daltons. They have suggested that proelastin is cleaved to smaller molecular weight forms of non-crosslinked elastin. It should be noted, however, that this view is not entirely supported by data from other laboratories. There are two reports on the use of isolated mRNA from chick aorta suggesting only a 70,000 dalton non-cross linked elastin is the major product of translation (37,38). There is also a recent report suggesting that aortic mRMA translates a 200,000 dalton putative elastin product (39). We have recently isolated a non-crosslinked elastin from the aortas of copper deficient chicks that appears to be 100,000 daltons (27). Its amino acid composition is similar to that for tropoelastin (Table III). A major problem in resolving these points is that the trypsin-like proteinase associated with elastin is not easily denatured or separated from the non-crosslinked forms of elastin. The proteinase is also not readily inhibited by commonly used inhibitors for trypsin-like proteinases (26). 

Inhibitors of Bowman-Birk types are widely distributed in plants and significantly different from the Kunitz inhibitor in their amino acid composition and are able to interact not only with trypsin, but with chymotrypsin (Valueva Mosolov, 2002 Rawlings et al., 2004). Inhibitors of Bowman-Birk type characterized by the presence of two reactive centers on a single polypeptide chain rich in cysteine (7 or more residues in one polypeptide), and the lack of amino acid residues tryptophan and tyrosine. The molecular weight of such inhibitors can vary from 8 to 16 kDa. Sometimes there are inhibitors that contain two domains on one polypeptide chain and active only in relation to one type of enzyme (Valueva Mosolov, 2002 Yan et al., 2009 Mosolov Valueva, 2008). 

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