When I was learning biochemistry in college (from good ol' Lehninger's Principles of Biochemistry), the section on protein function, protein binding affinities and dissociation constants with pKas and Kds being thrown around was a little hard to follow without good examples. I thought this story on the miracle berry's 'magical' effects might help any of you out there who are trying to learn about protein function and binding affinities:
Miracle Berry’s Sour-Sweet Mystery Cracked
Then ask yourself:
- Does the miraculin or sugar has a higher binding affinity?
- Which one has a higher Kd?
- If miraculin can only activate its receptor, hT1R2-hT1R3, at a low pH, can you guesstimate the pKa value is of the amino acid(s) on miraculin responsible for activating the hT1R2/hT1R3 receptors?
For the science nerds, here's the free, open-access original article out in PNAS that's out early ahead of the print date:
Human sweet taste receptor mediates acid-induced sweetness of miraculin