Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India. shashi@mbu.iisc.ernet.in|Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India. shashi@mbu.iisc.ernet.in|Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India. shashi@mbu.iisc.ernet.in|Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India. shashi@mbu.iisc.ernet.in|Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India. shashi@mbu.iisc.ernet.in|Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India. shashi@mbu.iisc.ernet.in