(R P)‐cAMPS inhibits the cAMP‐dependent protein kinase by blocking the cAMP‐induced conformational transition

FEBS Letters

Dostmann, Wolfgang R.G.¹ 

[1] Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str.29, 80802 München, Germany

关键词: cAMP-dependent protein kinase;    (R P)-cAMPS;    Protein folding;    Fluorescence spectroscopy;   

DOI  :  10.1016/0014-5793(95)01201-O

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

(R _P)-cAMPS is known to inhibit competitively the cAMP-induced activation of cAMP-dependent protein kinase (PKA). The molecular nature of this inhibition, however, is unknown. By monitoring the intrinsic tryptophan fluorescence of recombinant type I regulatory subunit of PKA under unfolding conditions, a free energy value (ΔG _D ^H2O) of 8.23 ± 0.22 was calculated. The cAMP-free form of the regulatory subunit was less stable with ΔG _D ^H2O = 6.04 ± 0.05 kcal/mol. Native stability was recovered by treatment of the cAMP-free protein with either cAMP or (S _P)-cAMPS but not with (R _P)-cAMPS. Thus, (R _P)-cAMPS binding to the regulatory subunit keeps the protein in a locked conformation, unable to release the catalytic subunit. This finding was further supported by demonstrating that holoenzyme formation was greatly accelerated only when bound cAMP was replaced with (R _P)-cAMPS but not with cAMP or (S _P)-cAMPS.

【 授权许可】

Unknown