Sulfur-rich protein, amino acid sequence

The sequence of appearance, relative amounts, and final relationships of cell components that survive lysis are presented diagrammatically in Figure 11. The smallest filaments that have been isolated (35 A thick) have low sulfur content (32). They thicken to 60-90 A with addition of sulfur-rich protein (demonstrated by heavy metal staining) (32, 64) and histidine-rich protein (demonstrated with radioactive labeling) (49). Five to 10 of these thickened filaments aggregate to form fibrils that average 250 A in diameter (70). Meanwhile, KH and ER protein accumulate until the cell is lysed when they are mixed and dispersed (47) to coat the 250-A fibrils (70). The coated fibrils are submerged in a matrix that includes nucleoproteins and nonfibrous proteins these incorporate about 10 times more sulfur than the fibrils (32). The insoluble fibrils and matrix constitute about 65% of the cornified cell (66) other components include 10% soluble keratin, 10% dialyzable substances (amino acids, etc.), 7-9% lipids, and about 5% membrane protein (65, 66). 

This sequence showed close amino acid composition, hydrophobicity profile and great homology with the small subunit of a 2S sulfur-rich albumin found in Bertholletia excelsa seeds (Brazil-nut). Infrared spectra (deuterium oxide solution, dry film) and circular dichroism studies of the small protein subunit from L usitata, indicated a great amount of ordered structure (72). 

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