Subtilisin protease inhibitors

A large number of potential reversible protease inhibitors exist (Laskowski Kato, 1980). Protein protease inhibitors like Strepromyces Subtilisin Inhibitor (SSI) (Hiromi et al, 1985) and Chymotrypsin Inhibitor (CI-2) (Jonassen, 1980 and McPhalen James, 1988) are known to be very strong inhibitors with inhibition constants at or below 10"10 M. 

Hiromi, K Akasaka, K Mitsui, Y Tonomura, B Murao, S (eds) (1985) Protein Protease Inhibitor - The Case of Streptomyces Subtilisin Inhibitor. Elsevier Amsterdam - Oxford - New York. 

Hexokinase Pyruvate kinase Adenylate kinase Phosphoglycerate kinase Phosphofructokinase Protease inhibitors Pancreatic trypsin inhibitor Soybean trypsin inhibitor Streptomyces subtilisin inhibitor Nucleases... 

Fig. 2.1 Structure of SSI subunit. (Reproduced with permission from Y., Mitsui, et al Protein Protease Inhibitor-The Case of Streptomyces Subtilisin Inhibitor (SSI) (K. Hiromi et al. ed.), p. 174, Elsevier, Amsterdam (1985)).

Subtilisin Carlsberg serine protease and protease inhibitor phenylmethylsulphonyl fluoride (PMSF) are from Sigma (St. Louis, MO). 

It appears from Fig. 2 that the ultrafiltered soy protein isolate is hydrolyzed considerably more slowly than the acid precipitated protein. This is due to the compact molecular structure of the ultrafiltered protein, which is still in the native state. That the degree of denaturation of a protein substrate has a profound influence on the kinetics of the proteolysis has been known for long, see Christensen W. It should be noted that subtilisin Carlsberg is not inhibited by the protease inhibitors present in native bean protein (7 ). 

Ikenaka, T. (1985) Chapter 4 in Protein Protease Inhibitor - The case of Streptomyces Subtilisin inhibitor, pp, 159-163, (K. Hiromi, K. Akasaka, Y. Mitsui, B. Tonomura and S. Murao, eds.) Elsevier Science Publishers, Amsterdam... 

CI2 (Figure 19.2) is a 64-residue polypeptide inhibitor of serine proteases.23 It has a binding loop (Met-40, which binds in the primary site of chymotrypsin or subtilisin), a single a helix running from residues 12 to 24, and a mixed parallel and antiparallel /3 sheet. The strands and the amphipathic helix interact to form... 

Data are adapted from compilations of Dure et at. (1989). O, high osmoticum (PEG or salt) D, desiccation C, cold W, wounding H, heat , untested or unknown. Sd, seed St, stem Pase, protease ASI, a-amylase/subtilisin inhibitor WGA, wheat germ agglutinin RNP, ribonuclear protein not organ specific. Table updated from Skriver Mundy (1990). 

Researchers at the biotech company EntreMed, Inc., have recently prepared and tested 2-phthalimidino-glutaric acid analogs of thalidomide and found them to be potent inhibitors of tumor metastasis [28], The key to the success of their synthesis was a resolution via enantioselective ester hydrolysis catalyzed by ChiroCLEC -BL, the CLC form of the protease subtilisin. The authors were able to isolate both enantiomers of the desired product with good optical purity (95% ee) (see Fig. 7). 

The purification and characterization of BmSI-7 and BmSI-6, two subtilisin inhibitors from Boophilus microplus (BmSI) was reported by Sasaki et al. (2008). The inhibitors were found to exhibit significant inhibition on the activity of purified Prl proteases from M. anisopliae. 

Sasaki, S. D., de Lima, C. A., Lovato, D. V., Juliano, M. A., Torquato, R. J. S., and Tanaka, A. S. (2008). BmSI-7, a novel subtilisin inhibitor from Boophilus microplus, with activity toward Prl proteases from the fungus Metarhizium anisopliae. Experimental Parasitology, 118, 214-220. 

Proteases are essential for the conversion of inactive proprotein precursors into the active neuropeptides. Two main protease pathways have been elucidated for processing proneuropeptides and hormones the recently discovered cysteine protease cathepsin L with aminopeptidase B and the well-established subtilisin-like serine proteases that consist of prohormone con-vertases 1 and 2 followed by carboxypeptidase E/H. Endogenous regulators modulate these two protease pathways as endogenous peptide inhibitors, activators, and in vivo secretory vesicle proteins. Neuropeptides in CSE (cerebrospinal fluid) in neurological diseases can monitor brain nervous activity because neuropeptides represent active neurotransmission (93, 94). 

---