“…This absorption spectrum is superimposable on those of horse and human HbNO in the presence of organic (poly)phosphates (c = 96 mM-1 cm-' and 99 mM-1 cm-' respectively at 415 nm) (Perutz, 1979;Ascenzi et al, 1988Ascenzi et al, , 1990Ascenzi et al, , 1992 (Figure 4a, spectrum B). These features suggest that chamois and steinbock HbNO, similarly to that reported for the nitric oxide derivative of opossum, ruminant (reindeer) and turtle Hb (John and Waterman, 1979a, b;Louro and Bemski, 1982;Ascenzi et al, 1990Ascenzi et al, , 1992Giardina et al, 1992b), is in a low-affinity conformation even in the absence of allosteric effectors (i.e., under the experimental conditions in which the functional data were obtained) (see Figure 1).…”