The heterogeneity and molecular weight of human haemoglobin derivatives after their reaction with glutaraldehyde was examined. When subjected to polyacrylamide gel electrophoresis the intact and modified haemoglobin markedly differ: the former shows two fractions in the molecular weight range of 20 000 daltons whereas a series of fractions of molecular weight of 35 000-100 000 daltons are observed after the reaction with glutaraldehyde. Simultaneously the dissociation curves of oxyhaemoglobin vary as a function of glutaraldehyde concentration. The samples of modified haemoglobin show a higher affinity for oxygen than intact haemoglobin.

The formation of heterogeneous fibers well observable under a magnifying glass in stirred "stroma-free" hemolysates of outdated banked erythrocytes was found to be predominantly due to random surface denaturation of both hemoglobin and non-heme proteins at the air-liquid interface. Electrophoretic analysis revealed that the precipitated and washed fibers contain residual membrane proteins as well as a certain amount of hemoglobin. The latter, however, largely remains in solution.

Using laser light scattering a rapid method for estimating relative counts of less deformable erythrocytes in blood samples was developed. The procedure is based on comparison of light scattering from blood cells deformed in defined shear stress and blood cells at rest, respectively.

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Molybdenum in the form of its pentavalent complex binds primarily to spectrin when incubated with erythrocytes. Only the band 1 subunit is involved in this interaction thus indicating some structural differences between spectrin subunits.