Proteases enzymatic activity

Coagulation Factors II, III, VII, IX, X, XI, and Xlla fragments, thrombin, and plasmin are classified as serine proteases because each possesses a serine residue with neighboring histidine and asparagine residues at its enzymatically active site (Table 3). Factors II, VII, IX, and X, Protein C, Protein S, and Protein Z are dependent on the presence of vitamin K [84-80-0] for their formation as biologically functionally active procoagulant glycoproteins. 

BLOOD CLOTTING. The formation of blood clots is the result of a series of zymogen activations (Figure 15.5). The amplification achieved by this cascade of enzymatic activations allows blood clotting to occur rapidly in response to injury. Seven of the clotting factors in their active form are serine proteases ... 

The first hint that two active-site carboxyl groups—one proto-nated and one ionized—might be involved in the catalytic activity of the aspartic proteases came from studies of the pH dependence of enzymatic activity. If an ionizable group in an enzyme active site is essential for activity, a plot of enzyme activity versus pH may look like one of the plots at right. 

The pH dependence of HIV-1 protease has been assessed by measuring the apparent inhibition constant for a synthetic substrate analog (b). The data are consistent with the catalytic involvement of ionizable groups with pK values of 3.3 and 5.3. Maximal enzymatic activity occurs in the pH range between these two values. On the basis of the accumulated kinetic and structural data on HIV-1 protease, these pK values have been ascribed to the... 

In the parental strain enzymatic activity reached the maximum value at 96 h. The hybrids H5, H15 and HIO showed good activity compared to Aspergillus sp. CH-Y-1043. Also, a difference with respect to parental strain was detected, a slight drop of activity in hybrids at 120 h. This effect was not due to changes of the pH during fermentation because it was similar in all cultures. The causes of this response in hybrids are unknown. More experiments for to evaluate the presence of proteases in the culture medium should be performed. Table 3 presents the data of the higher levels of endopectinases produced by... 

Urokinase is a serine protease produced by the kidney and is found in both the plasma and urine. It is capable of proteolytically converting plasminogen into plasmin. Two variants of the enzyme have been isolated a 54 kDa species and a lower molecular mass (33 kDa) variant. The lower molecular mass form appears to be derived from the higher molecular mass moiety by proteolytic processing. Both forms exhibit enzymatic activity against plasminogen. 

Fig. 2.2 ESI mass spectra obtained from the CPC spin column/ESI-MS screening assay of non-covalently bound protease-inhibitor complexes. Enzymatically active CMVP A144D/C87A/C138A/C161A A/as used in this experiment. (A) Reference ESI mass spectrum of impure inhibitor DFMK (MW 988.5 Da). (B) ESI mass spectrum of the spin column eluate of CMVP A144D/C87A/ C138A/C161A and DFMK, incubated at a...

---