Frequency domain lifetimes of liganded and unliganded hemoglobin measured with a 10-GHz instrument using front face geometry on a free liquid surface

Abstract

We present data on lifetimes of hemoglobin solutions obtained using a 10 GHz frequency domain fluorometer and a specially designed cuvette which allows front face excitation on a free liquid surface. The cuvette eliminates reflections and stray emissions, which become significant for low intensity fluorophores like hemoglobin. Three lifetimes are detectable in the subnanosecond range. At high frequency it is possible to detect components below 10 ps. The average lifetime of hemoglobin is ligand dependent, opening a new chapter in the investigation of the allosteric behavior of hemoglobin.