Influence of ATP and NO on denaturation onset of Hb samples. Influence of ATP and NO on denaturation onset of Hb samples (3 in each group) prepared in Na buffer (a) and K buffer (b). Arrows indicate the appearance of an additional peak in the NO-containing samples that denaturated markedly earlier than those without nitric oxide. The K buffer, containing both ATP and NO yet at room temperature (25°C) the average hydrodynamic radii reached values was 25 nm suggesting facilitated aggregation. Further increase in temperature induced formation of multiple large aggregates so that the measurement of Rh became impossible.