EXTENT OF RACEMIZATION OF SOME AMINO ACIDS IN DILUTE ALKALI-TREATED PROTEIN AND SOIL HUMIC AND FULVIC ACID

A study was made of the racemizing effect of mild alkaline treatment upon two proteins and humic and fulvic acid fractions from soils. It was found that the two proteins differed considerably so far as the beginning of racemization was concerned. Racemization of the soil fractions was significant in 24 hr, but was not radically different from gelatin, and in no case was the amino acid optical activity completely destroyed. Of the nine amino acids reported, all were less than 30% racemized by the 24 hr alkali treatment, and most were less than 20% racemized. Even in the amino acids most highly racemized-alanine, aspartic acid, phenylalanine, glutamic acid, and lysine-complete racemization did not occur after 96 hr. All other amino acids (valine, isoleucine, leucine, and proline) were less than 20% racemized in any 24 hr sample and that value was approached only by valine in the fulvic acid sample. While these results indicate that 0.5 N NaOH could be used as a soil extractant to indicate optical activity for life detection purposes, a milder extractant which would not affect the optical properties of the molecules of interest would be desirable. Further studies are now in progress. © 1968.