Ligno-protein complexes

At the end of the century there was general acceptance that HS are complex compounds of a synthetic nature formed as the result of decomposition involving two or more plant-derived materials. For example, Deherain (1902) considered that HS synthesis involves interactions between proteins and encrusting substances, mainly lignin. This concept was later developed as the ligno-protein complex of Waksman and Iyer (1932,1933) (see Section 1.4.5) and as described by Waksman (1936). 

FIGURE 4. Ligno-protein complex (Waksman and Iyer, 1932). 

In the latter part of the 1950s, this author (Hayes, 1960) attempted to repeat the experimentation used by Waksman and Iyer (1932,1933). He exhaustively washed powdered wheat straw with boiling water, then with hot dilute hydrochloric acid, and extracted twice for 5h in an autoclave at 120 °C, each time with a 4% sodium hydroxide solution. The combined filtrates were acidified to pH 4 with hydrochloric acid and the precipitate formed was washed free of chloride and freeze-dried. A ligno-casein complex was formed by reacting three parts of the lignin extract and one part casein in a 0.1 M solution of sodium hydroxide and collecting the precipitate formed when the pH was adjusted to 4. This complex was washed free of chloride and freeze-dried. A 6 1 lignin-protein complex was formed in the same way. 

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