Proton-Metal Cation Exchange in the Cell Wall of Nitella flexilis
When protons are exchanging for bivalent cations (Cu2+, Zn2+, or Ca2+) on the carboxylic groups of Nitella flexilis cell wall, the values of the respective global equilibrium constants do not change up to a protonation degree of 80%. These values drastically increase at higher proton concentrations...
| Main Authors: | , |
|---|---|
| Format: | Text |
| Language: | English |
| Published: |
1983
|
| Subjects: | |
| Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1066565 http://www.ncbi.nlm.nih.gov/pubmed/16663317 |
| Summary: | When protons are exchanging for bivalent cations (Cu2+, Zn2+, or Ca2+) on the carboxylic groups of Nitella flexilis cell wall, the values of the respective global equilibrium constants do not change up to a protonation degree of 80%. These values drastically increase at higher proton concentrations and tend to ≃3.4, which is the intrinsic pK value of the constitutive α-d-galacturonic acid monomer. These data suggest that the electric field in the matricial polymer and the cation bridges between pairs of negative sites have disappeared. |
|---|