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Creatine kinase isoenzymes specificities: histidine 65 in human CK‐BB, a role in protein stability, not in catalysis
Author(s) -
Mourad-Terzian Tamara,
Steghens Jean-Paul,
Min Kyung-Lyum,
Collombel Christian,
Bozon Dominique
Publication year - 2000
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/s0014-5793(00)01614-8
Subject(s) - isozyme , histidine , creatine kinase , biochemistry , chemistry , catalysis , enzyme
Creatine kinases (CK) play a prominent role in cell energy distribution through an energy shuttle between mitochondria and other organelles. Human brain CK was cloned and overexpressed in COS‐7 cells. We then deleted His‐65 and/or Pro‐66 situated near the center of a flexible loop as shown by X‐ray crystallography on mitochondrial and cytosolic CK. The ΔH65 mutant had nearly the same affinity for its substrates as wild isoenzyme, but its stability was very low. Unlike ΔH65, ΔH65P66 had a eightfold decreased affinity for creatine phosphate and was unable to dephosphorylate cyclocreatine phosphate. Our results demonstrate that, despite an overall similar shape of the proteins, this loop accounts for some subtle differences in isoenzyme functions.