Electronic measurements of single-molecule catalysis by cAMP-dependent protein kinase A


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Sims P. C., Moody I. S., Choi Y., Dong C., Iftikhar M., Corso B. L., ...Daha Fazla

Journal of the American Chemical Society, cilt.135, sa.21, ss.7861-7868, 2013 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 135 Sayı: 21
  • Basım Tarihi: 2013
  • Doi Numarası: 10.1021/ja311604j
  • Dergi Adı: Journal of the American Chemical Society
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.7861-7868
  • Ankara Hacı Bayram Veli Üniversitesi Adresli: Hayır

Özet

Single-molecule studies of enzymes open a window into their dynamics and kinetics. A single molecule of the catalytic domain of cAMP-dependent protein kinase A (PKA) was attached to a single-walled carbon nanotube device for long-duration monitoring. The electronic recording clearly resolves substrate binding, ATP binding, and cooperative formation of PKA's catalytically functional, ternary complex. Using recordings of a single PKA molecule extending over 10 min and tens of thousands of binding events, we determine the full transition probability matrix and conversion rates governing formation of the apo, intermediate, and closed enzyme configurations. We also observe kinetic rates varying over 2 orders of magnitude from one second to another. Anti-correlation of the on and off rates for PKA binding to the peptide substrate, but not ATP, demonstrates that regulation of enzyme activity results from altering the stability of the PKA-substrate complex, not its binding to ATP. The results depict a highly dynamic enzyme offering dramatic possibilities for regulated activity, an attribute useful for an enzyme with crucial roles in cell signaling. © 2013 American Chemical Society.