Validity of putative calcium binding loops of photoprotein aequorin.
Three peptides containing the putative Ca2+ binding loops, I, II and III, respectively, of a photoprotein, aequorin, from jellyfish Aequorea victoria were synthesized by a solid-phase procedure. The peptides bound Ca2+ with dissociation constants of 10(-3) to 10(-4) M, providing evidence for the assumption that Ca2+ binding loops are actually responsible for the binding of Ca2+. When the highly conserved 6th glycine residue in the 12-residue loops was replaced by arginine, no large effect was observed on Ca2+ binding. Exposure to a hydrophobic environment and the binding of Ca2+ brought about conformational changes to the peptides.
Oishi
O
O
Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan.
Nagatomo
A
A
Kohzuma
T
T
Oda
N
N
Miyazima
T
T
Ohno
M
M
Sakaki
Y
Y
D000331:Aequorin / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001059:Apoproteins / Q000737:chemistry; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D002147:Calmodulin / Q000737:chemistry; D002413:Cations, Divalent; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins; D037401:Scyphozoa
D001059:Apoproteins; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D002413:Cations, Divalent; D010446:Peptide Fragments; D011994:Recombinant Proteins; C060014:apoaequorin; D000331:Aequorin; D002118:Calcium