Reviewer 3 made the comment:

3. Secondly, unfortunately the authors apparently quantified DTT activities using a non-standard method, ie that of Li et al., 2009, which differs from the original DTT protocol described by Cho et al. (2005). The Cho method is widely utilized and is the basis for most DTT activities reported in the published literature. This means that the DTT activities reported here cannot necessarily be directly compared to generally published results, unless some type of conversion factor is given. This should be noted in the paper, discussed in detail (ie, difference in protocols explained), and optimally, a conversion factor given based on further experimental work by the authors.

You then gave a detailed answer to this. Can you please reproduce this in an appropriate manner please in the revised, MS, as you didn't add any text to the MS in response to this important point raised by the referee.

For points 12 and 13, you simply gave the response:
Author Response: Please refer to the above response to comment 4.

I would like you please to explicitly respond to each of these as separate responses, and if there is text in the response to comment 4 that is relevant, please cut and paste the relevant section. It is important that all comments have an explicit response, as 12 and 13 are different questions to comment 4.