For example : In this paper (http://www.jbc.org/content/274/5/2773.full).
They studied the high-affinity peptide transporter using rat kidney brush-border membrane vesicles and oocytes expressing rabbit renal PepT2.
And they conclude that with Hill coefficient (n H) close to 1 for charged and neutral peptides, suggesting a 1:1 stoichiometry.
I am not quite understand about this.
For a 1:n (receptor:ligand) stoichiometry the Hill coefficient nH will be within the range (0,n]. Thus, nH cannot be larger than the number of sites. Positive cooperativity is indicated by nH within (1,n]. Negative cooperativity is inidicated by nH within (0,1). Independent binding corresponds to nH equal to 1. Maximal cooperativity corresponds to nH equal to n.
The interesting point is that nH equal to 1 does not necessary mean that the number of ligand binding sites is 1. A value of 1 for nH means there are n independent ligand binding sites, but this does not impose any constrain for n. A value of m for nH means that there are, at least, m binding sites (m≤n).
- Badges
- Science topic
- Similar topics
- Chemistry
- Biochemistry