Proteinase variant activities

Figure 3. Modeling of proteinase K variant activity towards AAPL ip-NA following a 5 minute 65 heat treatment. Measured activities on the y-axis are compared with those predicted by the model on the x-axis. All activities were measured at 37°C and pH 7.0 using purified protein and are normalized to the activity of wild type proteinase K.

Figure 6. Principal component analysis of proteinase K variant activities. Seven measured proteinase K properties are shown compressed into two principal components. PCI (horizontal axis) capturing 60% of variance, PC2 (vertical axis) capturing22% of variance. Open squares represent each proteinase K variant, filled circles show the positions of each property in principal component space. Properties are activity towards casein, activity towards AAPL-p-NA at pHJ.O, pH5.5 and pH4.5, activity towards AAPL-p-NA after heating at 65° for 5 minutes (absolute), fraction of original activity towards AAPL-p-NA remaining after heat treatment (residual), product of absolute and residual activities (product).

N2. Neri, A., Bohoslawec, O., Anderson, T. D., and Tokes, Z. A., Differential release of active proteinase inhibitors by 2 rat mammary adenocarcinoma variants possessing different metastatic potentials. Cancer Res. 51, 1318-1325 (1991). 

We used our PLSR-based sequence activity relationship to assign a regression coefficient to each varied amino acid. We then calculated the predicted activity for a proteinase K variant by summing the regression coefficients for amino acid variations that are present in that variant. In this case we did not include terms to account for interactions between the varied amino acids, though this can also be done 13). Figure 3 shows a good correlation between the predictions of our calculated sequence-activity relationship and the measured ability of heat-treated proteinase K variants to hydrolyze AAPL-p-NA. 

Figure 6 shows the distribution of 7 proteinase K properties following calculation of the principal components of the 7-dimensional activity data (33). Eighty two percent of the variation in the data could be captured in just two dimensions. The activities of variants towards AAPL-p-NA at different pHs was highly correlated, as were the different methods of measuring heat tolerance. Substrate specificity of the proteinase K variants is the most distinguishing trait... 

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