Protease molecular weight

Organism Name of protease Type of protease Molecular weight (kDa) Isoelectric point Inhibitors Reference... 

Factor II. Prothrombin is a vitamin K-dependent compound synthesized by the Hver. When prothrombin is activated it is cleaved at two sites, resulting in a two-chain molecule linked by a disulfide bond that has a molecular weight of 37,000 daltons. Thrombin is the serine protease that initiates the conversion of soluble fibrinogen into fibrin. 

Factor XI. Factor XI is a Hver-synthesized glycoprotein that circulates in a zymogen form as a dimer. It is converted to its active serine protease form by Factor Xlla in the presence of high molecular weight kininogen. Calcium is not required for this activation step. 

Most aspartic proteases are composed of 323 to 340 amino acid residues, with molecular weights near 35,000. Aspartic protease polypeptides consist of... 

Factor Xlla is a serine protease that activates FXI to FXIa (Fig. 5). This system is not of physiologic relevance since patients with hereditary deficiencies of factor XII, prekallikrein, and high-molecular weight kininogen do not present with bleeding symptoms. 

Plasmepsin II. The malarial aspartyl protease plasmepsin II has a significant homology (35%) to cathepsin D. Correspondingly, the very same approach as for the cathepsin D inhibitors (see above) was followed. The best inhibitors have Ki values of 2-10nM, a molecular weight <650, moderate selectivity vs. cathepsin D, the most closely related human protease, log P values <4.6, and no apparent binding to human serum albumin, for example, compound 36 Ki plasmepsin II = 2.0nM, Ki cathepsin D = 9.8nM Fig. 16.5) [111]. 

Enzymatic synthesis of aliphatic polyesters was also achieved by the ringopening polymerization of cyclic diesters. Lactide was not enzymatically polymerized under mild reaction conditions however, poly(lacfic acid) with the molecular weight higher than 1 x 10" was formed using lipase BC as catalyst at higher temperatures (80-130°C). Protease (proteinase K) also induced the polymerization however, the catalytic activity was relatively low. 

Meanwhile we have shown that the excision activation of ICOR channels is due to disinhibition [72]. The respective inhibitor, operationally named cytosolic inhibitor (Cl), is present in the cytosol of placenta trophoblast cells HT29- and Tg4-colonic carcinoma cells and RE cells of normal and CF patients. The molecule has an apparent molecular weight of 700-1 500 Da it is amphiphilic heat stable and not digested by trypsin, proteases, nucleotidases, lipases or amylase [72]. Burc-khardt, Fromter and their collaborators [114] have confirmed our results and extracted a similar or identical Cl from kidney cortex. 

Coumarincarboxylate derivatives are versatile, efficient, low molecular weight, nonpeptidic protease inhibitors. Both esters and amides behave as time-dependent inhibitors of a-chymotrypsin but the esters are clearly more efficient than the corresponding amides. The criteria for a suicide mechanism are met. The presence of a latent alkylating function at the 6-position (chloromethyl group) is required to produce to inactivation by a suicide mechanism (Scheme 11.3, pathway a). Aryl esters, in particular the meta-substituted phenyl esters are the best inhibitors. Thus, m-chlorophenyl 6-(chloromethyl)-2-oxo-27/-l-benzopyran-3-carboxylate is one of the well-known inactivator of a-chymotrypsin (kJK, = 76(),000M s 1 at pH 7.5 and 25 °C, Table 11.1). 

Pepsin consists of a single polypeptide chain of molecular weight 34 644 and 327 amino acid residues. Ser-68 is phosphorylated, but this phosphate may be removed without significantly altering the catalytic properties of the enzyme. As in other acid proteases, the active site is an extended area that can accommodate... 

The N-terminal sequence of one peptide from the 35 kDa zone of H-gal-GP showed some homology to cathepsin B-like cysteine proteases. Molecular cloning has also identified a thrombospondin homologue associated with the diffusely staining region between zones A and B, a galectin associated with zone D (Newlands et al., 1999) and a low molecular weight (approximately 13 kDa) cysteine protease inhibitor, cystatin. 

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