16 



pected that other proteins will show a similar behavior. 

 In these experiments it has been shown that a dry mono- 

 molecular film of egg albumin is 20 Angstrom units thick, 

 and is hydrophilic on one side and hydrophobic on the 

 other side. It behaves like a two-dimensional network 

 in which the units are connected by strong elastic springs. 

 All of this is in perfect agreement with the writer's sys- 

 tem of protein structure. If we accept the recent reports 

 of chemists that the molecule of egg albumin has 288 

 amino acid residues ( Joukn. Biol. Chem., 118, 301, 1937), 

 and that they are arranged in groups of 18, then the en- 

 tire molecule will consist of a cluster of nine double- 

 strand polypeptide spirals forming two rectangular com- 

 partments, each measuring approximately 4.5 x 10 Ang- 

 strom units. Each of these double-strand spirals will 

 consist of a column of 16 superimposed diketopiperazine 

 rings. When the material is thoroughly dried, these may 

 be assumed to be closely nested upon one another, and 

 will then form a column exactly 20 Angstrom units high. 

 Since natural amino acids are always of the same optical 

 activity (usual left-handed) it must be assumed that the 

 h;fdrocarbon side-chains along the sides of the spirals 

 always slant in the same direction, so that the double- 

 strand spirals, and in fact the entire protein molecule, 

 will be definitely hydrophilic at one end (the carboxyl 

 end), and hydrophobic at the other end (the amino end). 

 Consequently when these molecules are all arranged with 

 the same ends up, they will form a monomolecular film 

 which will be hydrophilic on one side and hydrophobic on 

 the other side. It will also be seen from the diagrams 

 that the protein molecule has exposed rows of hydroxyl 

 groups along the corners. These will form chemical 

 bonds with the sides or corners of adjacent molecules, 

 there being several points on the periphery of each mole- 

 cule where such bonds could be formed. Since the mole- 

 cules will have a random distribution in the plane of the 



