Couple of changes here.
1. Changed some of the text to make it clear that it is A which undergoes some conformational change that increases its binding affinity for B. The previous "changes the binding affinity of the second B molecule" was not as exact wording. Could also just change it to "changes the binding affinity FOR the second B molecule and not include "A's". Lmk what you think
2. Gave an explanation of Hill's coefficient which is related to cooperativity.
3. Got rid of "results in sigmoidal curve." We already have a card that states that positive cooperative binding results in a sigmoidal curve. If we choose to leave this detail the current card has to be edited to include that it is specifically a positive cooperative binding enzyme that displays a sigmoidal curve because as is it implies both positive and negative cooperative binding create a sigmoidal curve which isn't true.
For hill's coefficient:
Kaplan. Biochem. 2.3.