Effects of Neutral Salts and Alcohols on the Activity of Streptomyces caespitosus Neutral Protease

ArticleinJournal of Biochemistry 142(3):317-24 · October 2007with1 Read
Impact Factor: 2.58 · DOI: 10.1093/jb/mvm134 · Source: PubMed


    Streptomyces caespitosus neutral protease (ScNP) is one of the smallest metalloproteinase with a molecular mass of 14 kDa. Effects of solvent composition
    on ScNP activity were examined using a peptide substrate. The kcat/Km values of ScNP exhibited bell-shaped pH-dependence with the optimal pH of 6.4–7.0 and the pKa values of 5.0 ± 0.1 and 8.3 ± 0.1. ScNP activity increased in an exponential fashion with increasing [NaCl]. The relative kcat/Km value at 3.6 M NaCl to that at 0 M NaCl was 3.7, and the degree of the activation at x M NaCl was expressed as 1.2 x (x < 2.0) and 1.4x (x > 2.0). On the other hand, ScNP activity decreased with increasing concentrations of LiCl, KCl, NaBr, LiBr, KBr and NaClO4. Alcohols inhibited ScNP activity with the IC50 values, the concentration required for decreasing the activity at 50% of the maximum, of 0.77–6.54 M. The order of the inhibitory
    potency was 1-butanol, 2-methyl-1-propanol, 2-methyl-2-butanol > 2-methyl-2-propanol, 2-butanol, 1-propanol > 2-propanol ≫ ethanol ≫ methanol. The activities recovered completely by the dilution of alcohols, suggesting that the ScNP
    inhibition by alcohols is reversible. These characteristics of ScNP are compared with those of human matrix metalloproteinase
    7 and thermolysin.

    Similar publications