For instance if you increase the amount of Tris but pH still does not change then will the enzyme activity still proceed normally? If it does change the pH will it change enzyme structure and why?

  • $\begingroup$ I am a novice at biology, but googling "amylase ph" resulted in a recommended pH of 7.0 for "Human pancreatic alpha-amylase" . So wouldn't it depend on the pH of the Tris, which I forgot, since there are alot of different kinds of tris buffer preps? Googling "Tris" resulted in a wikipedia page with the pH being 8.0. So given that information, wouldn't it have less functionality? $\endgroup$
    – Ro Siv
    Sep 12, 2015 at 21:19
  • $\begingroup$ Would increasing the amount Tris but no change in pH do anything significant? $\endgroup$
    – cambelot
    Sep 12, 2015 at 21:36
  • $\begingroup$ To be honest, I wouldn't know. But increasing the amount of the Tris would cause a change in pH would it not? Unless you mean to balance it with something basic or acidic? And then in that case i still would not know. I always thought TRIS was just used to obtain the optimal pH for enzymes and the like and the pH was its reason for being used. $\endgroup$
    – Ro Siv
    Sep 12, 2015 at 21:40
  • $\begingroup$ Assuming the Tris is chemically inert to the reaction, a higher amount of Tris will increase the buffering capacity (i.e. the pH changes less). $\endgroup$
    – March Ho
    Sep 13, 2015 at 0:09

2 Answers 2


I realize I'm 4 years late, but wanted to give an answer to this. It appears that tris often has inhibitory effects on amylase activity. Adding more Tris will lead to competitive inhibition with the substrate and will skew the results.

Binding of Tris to Bacillus licheniformis alpha-amylase can affect its starch hydrolysis activity https://www.ncbi.nlm.nih.gov/pubmed/18289113


After 4 years of working in enzymology I've got say tris is really tricky first of all when you use more tris to keep pH at the same as before you will need to re adjust the pH as tris is about 9 but most enzymes work around 6to7.5 (for alpha amylase it's 5.8) if you don't then your enzyme wont work properly ,it needs very low or high pH grade to destroy 3D structure of enzyme ,so we can simply say it will lost it's functionality , if you adjust the pH high concentration can cause some problem such as surrounding substract here amylase and not letting it to connect to enzyme in some cases acid you use to adjust pH has toxic effects on enzyme chlorine in this case but pretty sure the best way is optimization to understand the reaction. Best regards .


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