Talk:Proteinase K

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Optimal Temperature for Proteinase K

The temperature for highest proteinase K activity is listed at 50-60C on many sites, including this one, with no provided references. Multiple papers have found proteinase K to be most active at 37C (room temperature) with decreased activity at temperatures above 45C. See here: The enzymatic activity of proteinase K is controlled by calcium (Bajorath et al. 1988) http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1988.tb14301.x/epdf

Response: Higher temperatures aids PK activity by (fully or partially) unfolding substrate proteins. In the study referenced above enzymatic activity was determined using a chromogenic peptide which does not require unfolding. Therefore, no positive effect of increased temperature would be expected. — Preceding unsigned comment added by 149.13.178.149 (talk) 09:17, 6 November 2018 (UTC) [reply]

There is a distinction between optimal performance and relative activity rate. Relative activity rate refers to the proteolytic activity of the enzyme. Optimal performance refers to the enzyme's ability to perform in a manner that best suits the procedure at hand. With this is mind, 'optimal performance' may occur at diminished proteolytic rates noted at higher temperatures, depending on the needs of the process. However, citations are needed for either 1) the claim that activity increases at 50-60C or 2) the claim that optimal performance (for particular procedures, such as DNA extraction) is achieved at 50-60C. — Preceding unsigned comment added by 24.38.10.6 (talk) 19:46, 20 February 2018 (UTC)[reply]