A-Trypsin

Guo Z and C L Brooks III 1998. Rapid Screening of Binding Affinities Application of the A-Dynamics Method to a Trypsin-Inhibitor System. Journal of the American Chemical Society 120 1920-1921. 

It has been shown [18] that when high cone-voltages were used in conjunction with negative-ion electrospray, phosphopeptides produce diagnostic ions at m/z 63 (P02 ) and m/z 79 (P03 ). LC-MS analysis of a trypsin digest of bovine... 

Matthews DA, Smith WW, Ferre RA, Condon B, Budahazi G, Sisson W, Villafranca JE, Janson CA, McElroy HE, Gribskov CL et al (1994) Structure of human rhinovirus 3C protease reveals a trypsin-like polypeptide fold, RNA-binding site, and means for cleaving precursor polyprotein. CeU 77 761-771... 

Figure 42-12. Structure of human proinsulin. Insulin and C-peptide molecules are connected at two sites by dipeptide links. An initial cleavage by a trypsin-like enzyme (open arrows) followed by several cleavages by a car-boxypeptidase-like enzyme (solid arrows) results in the production of the heterodimeric (AB) insulin molecule (light blue) and the C-peptide.

This signal peptide might have been eliminated by a trypsin-like protease cleavage (Benoist et al., 1987) since an Arg occurs in the CLPGl sequence, as in the case of PG of F. momUfonne and of PGII of A. niger (Bussink et al., 1991 Caprari et al., 1993). 

The pancreatic juice is released through the ampulla of Vater into the duodenum to aid in the digestive process as well as buffer acidic fluid released from the stomach (Fig. 20-1). The pancreas contains a trypsin inhibitor to prevent autolysis. 

An acid phosphatase and a trypsin inhibitor94 also are presumed to form part of the protein complement in green coffee. 

Guo, Z.Y. Brooks in, C.L., Rapid screening of binding affinities application of the lambda-dynamics method to a trypsin-inhibitor system, J. Am. Chem. Soc. 1998,120, 1920-1921... 

It is generally believed that proteases enhance cancer spread primarily by catalyzing degradation of the extracellular matrix. Since multiple substrates are encountered in this matrix, a number of different proteases are likely to be required to complete the metastatic process. Multiple proteases may also be required to activate different inactive precursor forms. Thus, in vitro, plasmin (D7), cathepsin B (D7), and a trypsin-like protease (K12) can all activate pro-uPA, while plasmin, which results from the action of uPA on plasminogen, can activate certain metalloproteases (M4). As mentioned earlier, completion of the metastatic process may require a cascade of different proteases operating, as shown in Fig. 2. 

Despite their lack of stabilizing disulfide bridges Potl inhibitors feature a common, stable fold. The N-terminus is coiled, although in some structures a small /3-strand has been identified. After a turn the structure adopts an a-helical structure, followed by a turn and an other /3-strand. The sequence then features an extended turn or loop motif that contains the reactive site of the inhibitor before it proceeds with a /3-strand running almost parallel to the /3-strand after the a-helix. After another turn and coiled motif a short /3-strand antiparallel to the other /3-strands precedes the coiled C-terminus. Usually the N-terminal residue in the reactive site is an acidic residue followed by an aromatic amino acid, that is, tyrosine or phenylalanine. Figure 11 shows the complex of chymotrypsin inhibitor (Cl) 2 with subtilisin, the hexamer of Cl 2 from H. vulgare and a structural comparison with a trypsin inhibitor from Linum usitatissimum ... 

The classical pathway may be activated immunologically by antigen-antibody complexes and aggregated immunoglobulins, and non-immunologically by a number of chemically diverse substances, including DNA, C-reactive protein. Staphylococcal protein A, trypsin-like enzymes and certain cellular membranes (Table III). 

Figure 8.4. Amino acid sequence of porcine insulin is depicted in (a). Trypsin cleavage sites are also indicated. Trypsin therefore effectively removes the insulin carboxy-terminus B chain octapeptide. The amino acid sequence of human insulin differs from that of porcine insulin by only one amino acid residue. Porcine insulin contains an alanine residue at position 30 of the B-chain, whereas human insulin contains a threonine residue at that position. Insulin exhibiting a human amino acid sequence may thus be synthesized from porcine insulin by treating the latter with tr5q)sin, removal of the C terminus fragments, generated and replacement of this with the synthetic octapeptide shown in (b). Reproduced by permission of John Wiley Sons Ltd from Walsh Headon (1994)...

Laskowski and Laskowski (1950, 1951) found a trypsin inhibitor in colostrum in relatively large amounts on the first day after parturition and in decreasing amounts thereafter. They crystallized both the inhibitor and the trypsin-inhibitor complex, which consists of a trimer containing three molecules of trypsin and three molecules of the inhibitor (Laskowski et al. 1952). 

Fig. 14. The rate of hydrolysis of RNase relative to that of Ox-RNase as a function of temperature. The proteases used were (O) aminopeptidase, (A) trypsin, ( ) chymotrypsin, and ( ) carboxypeptidase. Reproduced from Klee (.340).

Analysis of the growth promoter 4-hydroxy-3-nitrophenylarsonic acid (roxarsone) has been investigated by Dean et al. [78]. Tissue, sampled from chickens with a roxarsone supplemented diet was digested using a trypsin enzymolysis technique. Anion-exchange chromatography was used to per-... 

Shivraj, B., Rao, H. N., and Pattiraman, T. N. (1982). Natural plant inhibitors. Isolation of a trypsin/a-amylase inhibitor and a chymotrypsin inhibitor from ragi (Eleusine coracana) grains by affinity chromatography and study of their properties. J. Sci. Food Agric. 33,1080-1091. 

The reverse action of a trypsin-free elastase isolated from porcine pancreas was studied in frozen aqueous systems and was found to catalyze peptide bond formation more effectively than in solution at room temperature (Haensler, 1998). The acceptance of free amino acids as nucleophilic amino components indicates a changed specificity of the endoprotease in frozen reaction mixtures. In elastase-catalyzed formation of Ser-, lie-, and Val-X-bonds in frozen aqueous reaction mix-... 

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