Pepstatin inhibitor

Pepstatin (see page 531) is an extremely potent inhibitor of the monomeric aspartic proteases, with A) valnes of less than 1 nM. 

Inhibitors which interact only with peptidases of one catalytic type include pepstatin (aspartic peptidases) E64 (cysteine peptidases from clan CA) diisopropyl fluorophosphates (DFP) and phenylmethane sulfonyl-fluoride (PMSF) (serine peptidases). Bestatin is a useful inhibitor of aminopeptidases. 

Poly(L-lysine) has also been suggested as a carrier for pepstatin, a specific inhibitor of the lysosomal proteinase cathepsin D, responsible for causing muscle-wasting diseases, such as muscular dystrophy [257],... 

The mutation of the hydroxyl group positioned in R-configuration at the C(3) atom of the central statine (rSta) residue of the inhibitor gives rise to AAGbind of -0.51 kcal/mol, which is very close to the experimental value of -0.8 kcal/mol. It may be noted here that the starting configuration of the inhibitor in the enzyme-inhibitor complex is the same as that of pepstatin. The crystal structure of rhizopus pepsin or any other aspartic proteinase... 

K. Suguna, E. A. Padlan, R. Bott, J. Boger, K. D. Parris, and D. R. Davies, Structures of complexes of rhizopus pepsin with pepstatin and other statine-containing inhibitors, Proteins 13 195 (1992). 

H. Umezawa, T. Aoyagi, H. Morishima, M. Matsuzaki, and M. Hamada, Pepstatin, a new pepsin inhibitor produced by actinomycetes, J. Antibiot. (Tokyo) 23 259 (1970). 

D. H. Rich, and E. T. Sun, Mechanism of inhibition of pepsin by pepstatin. Effect of inhibitor structure on dissociation constant and time-dependent inhibition, Biochem. Pharmacol. 29 2205 (1980). 

Wu et al. (1998) noted that doxombicin-induced apoptosis in lymphoid cells was blocked by pepstatin A, which is an inhibitor of cathepsin D. These investigators also observed that cathepsin D was induced through p53 DNA-binding sites at the cathepsin D promoter. Moreover, they have foimd that, compared to fibroblasts from wild-type mice, cathepsin D-/- fibroblasts from gene knock-out mice exhibited increased resistance to death caused by doxombicin. Also, in semm-deprived rat PC 12 cells undergoing apoptosis, the amoimt of cathepsin B has been observed to decline, while the level of cathepsin D increased (Shibata et al, 1998), and, in our laboratory (Kagedal et al, 2001), the same phenomenon was recently seen in human fibroblasts exposed to naphthazarin. 

The syndecan family of heparin sulfate proteoglycans (HSPGs) plays critical roles in several signal transduction pathways, and syndecan 3 intramembrane proteolysis is presenilin/y-secretase dependent (357). COX2 and COXl potentiate ABP formation through mechanisms that involve y-secretase activity. Sulindac sulfide and other NSAIDs (ibuprofen, indomethacin, R-flurbiprofen) selectively decrease the secretion of ABP independently of COX activity, probably via y-secretase inhibition (358-360). Pepstatin A methylester, sulfonamides, and benzodiazepines can also act as potent, noncompetitive, y-secretase inhibitors (335). These are but a few examples of the potential repercussions and biochemical consequences that the pharmacological manipulation of secretases in AD may bring about. 

Fungal and Yeast Protease CocktaiL These should contain the following inhibitors AEBSF, pepstatin A, E-64, and 1,10-phenanthroline. 

Mammalian Cell Protease Inhibitor CocktaiL These should contain AEBSF, pepstatin A, E-64, bestatin, leupeptin, and aprotinin. (Metal chelators can be added to suppress the activity of calcium ion-dependent proteases such as calpain. Again, one must determine whether the protein or enzyme being purified does not require a divalent metal cofactor for stabihty or activity.)... 

Bacterial Extract Protease CocktaiL Inhibitors present are pepstatin A, 4-(2-amino-ethyl)benzenesulfonyl fluoride (AEBSF), rrans-epoxysuccinyl-L-leucylam-ido(4-guanidino)butane (E-64), bestatin, and sodium EDTA. 

Thus, although pepstatin still may be considered a transition-state analog inhibitor owing to the tetrahedral geometry at C-3 of statine, pepstatin is also a collected-... 

We synthesized the ketomethylene, , and hydroxyethylene,8, isosteres of a Leu-Ala dipeptide sequence in order to explore the importance of the two extra atoms in statine relative either to substrate or to the tetrahedral intermediate (Figure 1) in another aspartyl protease system. The compounds were synthesized by the routes outlined in Scheme I. This route was chosen so as to provide steric control at C-2 and C-5 of both 7 and 8 as well as to provide ready access to C-4 labeled analogs. Details of the synthesis have been described else-where.(23.24) Inhibitors were synthesized in which Leu-Ala dipeptide Isosteres replaced either Sta or Sta-Ala in known pepstatin analogs. Inhibition of porcine pepsin was determined using the reported spectrophotometric assay (Table I).(25)... 

---