Journal of Chemical Sciences

, Volume 115, Issue 4, pp 307–317

Kinetics of proton transfer in a green fluorescent protein: A laser-induced pH jump study

  • Roop Mallik
  • Jayant B. Udgaonkar
  • G. Krishnamoorthy
Article

DOI: 10.1007/BF02704222

Cite this article as:
Mallik, R., Udgaonkar, J.B. & Krishnamoorthy, G. J Chem Sci (2003) 115: 307. doi:10.1007/BF02704222

Abstract

The sub-millisecond protonation dynamics of the chromophore in S65T mutant form of the green fluorescent protein (GFP) was tracked after a rapid pH jump following laser-induced proton release from the caged photolabile compoundo-nitrobenzaldehyde. Following a jump in pH from 8 to 5 (which is achieved within 2 μs), the fluorescence of S65T GFP decreased as a single exponential with a time constant of ∼90 μs. This decay is interpreted as the conversion of the deprotonated fluorescent GFP chromophore to a protonated non-fluorescent species. The protonation kinetics showed dependence on the bulk viscosity of the solvent, and therefore implicates bulk solvent-controlled protein dynamics in the protonation process. The protonation is proposed to be a sequential process involving two steps: (a) proton transfer from solvent to the chromophore, and (b) internal structural rearrangements to stabilize a protonated chromophore. The possible implications of these observations to protein dynamics in general is discussed

Keywords

Green fluorescent protein proton transfer pH-jump caged proton protein dynamics 

Copyright information

© Indian Academy of Sciences 2003

Authors and Affiliations

  • Roop Mallik
    • 1
  • Jayant B. Udgaonkar
    • 1
  • G. Krishnamoorthy
    • 2
  1. 1.National Centre for Biological SciencesTata Institute of Fundamental ResearchBangaloreIndia
  2. 2.Department of Chemical SciencesTata Institute of Fundamental ResearchMumbaiIndia
  3. 3.Department of Developmental & Cell BiologyUniversity of California IrvineIrvineUSA