Dear Author
Thanks for submitting a revised version of your manuscript addressing reviewers' comments. There was consensus among the three reviewers in that this is an important manuscript that clarifies some of the concepts related to modeling enzyme kinetics in soil biogeochemical models. Furthermore, the manuscript has the potential to facilitate the implementation of enzyme-substrate reactions in biogeochemical models and it could motivate future research.
Before accepting the manuscript for publication in GMD, I would like you to address a few minor issues remaining in the revised version.
1. Please spell-out the meaning of the subscript T in the concentrations starting at the bottom of page 6.
2. You still need to be more specific with the description of the approximation of the term \sqrt(1-4 \epsilon) on page 7. It seems to me that this is a first-order term of a Taylor expansion evaluated at \epsilon = 0. You need to mention this, i.e. that the approximation is a first order term from a Taylor-series expansion evaluated at a specific value of epsilon.
3. Page 15, lines 13-15. I don’t understand this sentence. Both quadratic kinetics and ECA are approximations, as explicitly recognized in their names, to the system of equations given by eqns 2-5. You didn’t show here the exact analytical solution of this system of equations. Please clarify this sentence.
4. Page 16, line 9. 'biogeochemical'. Also page 15, line 13: 'quasi-steady-state'.