[Determination of the accessible surface of lysozyme and human serum albumin molecules by the total tritium labeling method].

Amino acids composing an accessible surface of lysozyme and human serum albumin (HSA) globules were determined by the total tritium labelling method. A good correlation between our data on the distribution of the tritium label for the lysozyme molecule and X-ray data on the tertiary structure for this macromolecule was received. Lysozyme was used as a standard for determining the accessible surface of the globule albumin. It was shown that the accessible surface of the albumin globule is substantially more hydrophobic (average accessible surface area of hydrophobic amino acids is 130 A2 in HSA and 20 A2 in lysozyme) than in lysozyme. The HSA molecule is characterized by high values of: the accessible surface area, the ratio of extended area to the folded one, and the surface roughness index. These data indicate that the HSA molecule is less compactly packed than lysozyme.