Taq was never opened, but already expired, PCRs working great. What is happening with taq after expiration date? Does it get less efficient? How is the proofreading affected?
- Expiry dates are just a guide
- Taq is designed to withstand high temp and is generally therefore stable; even beyond the expiry date
- if your aliquot of Taq has never opened and therefore freeze thawed it is likely to retain full activity especially if less than 1 year over the expiry date
- Moreover if the 'expired taq' is actually working then so will it's proof reading
- In time with freeze thawing you will find that enzyme activity will start to significantly decrease and when that happens polymerisation efficiency as well as attendant proof reading will also decrease. You do not lose one facility without the other
- Expiry dates are just a guide
- Taq is designed to withstand high temp and is generally therefore stable; even beyond the expiry date
- if your aliquot of Taq has never opened and therefore freeze thawed it is likely to retain full activity especially if less than 1 year over the expiry date
- Moreover if the 'expired taq' is actually working then so will it's proof reading
- In time with freeze thawing you will find that enzyme activity will start to significantly decrease and when that happens polymerisation efficiency as well as attendant proof reading will also decrease. You do not lose one facility without the other
I agree with Laurence. When stored properly Taq should be fine for years. It isn't the length of storage but the freeze/thaw cycles that are the most detrimental.
Hi,
I agree with those who suggest that expiration date is more like a guarantee that if you use the product before the specified date, it shoudl work 100%, however, it does NOT mean that after the expiration date, it should not work.
I am a little less sure about the proofreading activity, as a lot of times higher proofreading activity is derived from another enzyme in the Taq polymerase (mix). If this is true in your case, then in theory you can not be sure that this "other enzyme" is as stable as your Taq enzyme. You can check the specifications of your Taq enzyme if it is in fact a mix of 2 enzymes, too.
Having said that, there are 2 things:
1. Most enzymes are more stable than they expiration date suggests (often, lot more stable)
2. If HiFi is so important, you want to sequence your cloned product anyway.
So I woul go ehaed and use your "expired" enzyme, but would sequence the end result.
T
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