Micro-Raman characterisation of the R to T state transition of haemoglobin within a single living erythrocyte

AbstractWe present the first recorded Raman spectra of haemoglobin in both the R and T states from within a single living erythrocyte using 632.8 nm excitation. Bands characteristic of low spin haems are observed in oxygenated and carboxylated erythrocytes at approx. 1636 (ν10), 1562–1565 (ν2), 1250–1245 cm−1 (ν13) and 1226–1224 cm−1 (ν5+ν8). The spectra of deoxygenated and methaemoglobin erythrocytes have characteristic high spin bands at approx. 1610–1606 cm−1 (ν10), 1582–1580 (ν37), 1547–1544 (ν11), 1230–1220 cm−1 (ν13) and 1215–1210 cm−1 (ν5+ν8). Bands at 1172 (ν30), 976 (ν45) and 672 (ν7) cm−1 appear to be enhanced at 632.8 nm in low spin haems. The oxidation state marker band (ν4) at 1364–1366 cm−1 appeared invariant within this domain in all single cells and conditions investigated contrary to other resonance Raman studies on haem isolates. The information gained by in vivo single erythrocyte molecular analysis has important ramifications to the understanding of fundamental physiological processes and may have applications in the diagnosis and treatment of red blood cell disorders