I understand that enzyme concentration does'nt affect Km since the Micaelis Menten equation is based on the steady state approximation wich requires high levels of substrate compared to enzyme (that's why changing enzyme concentration is negligible compared to substrate concentration and therfore there is no apparent change in Km). but what about change of temperature or pH? it's known that change in those parameters can change enzyme activity, but does this actually can change kinetic parameters like Km? Why should i think not? because the same explanation that says that change in enzyme concentration does'nt affect Km sould be applied here. there is a lot of substarate anyway and therefore there should not be apparent change in the Km? or am I wrong? another issue which makes me think so: In all the biochemistry literature that I have encounterd Km and Kcat appears for each enzyme with no indication of the temperature or pH for wich thouse values were observed (not in Leninger, nor Wikipedia or other textbooks).
I couldn't find any orderd explanation about this issue.