Premium
1 H‐NMR studies of the histidine residues of human choriogonadotropin and its α‐ and β‐subunits
Author(s) -
Frankenne F.,
Maghuin-Rogister G.,
Birdsall B.,
Roberts G.C.K.
Publication year - 1983
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(83)80068-4
Subject(s) - histidine , protein subunit , imidazole , chemistry , stereochemistry , biochemistry , crystallography , biophysics , biology , amino acid , gene
The pH‐dependence of the chemical shifts of the imidazole C2‐proton resonances of the 4 histidine residues of human choriogonadotropin has been determined in the intact hormone and in its isolated α‐ and β‐subunits. The single histidine of the β‐subunit and two of the histidines of the α‐subunit show only minor changes in pK when the subunits recombine. However, one histidine of the α‐subunit, tentatively identified as Hisα83, has a very low pK (≤2.4) in the isolated subunit and increases markedly on recombination with the β‐subunit, strongly suggesting that a conformational change occurs. This behaviour is closely similar to that reported earlier for porcine lutropin.