Microbiological method for the determination of L-tryptophan.

Journal of Bacteriology
O K Sebek

Abstract

Sebek, Oldrich K. (The Upjohn Company, Kalamazoo, Mich.). Microbiological method for the determination of l-tryptophan. J. Bacteriol. 90:1026-1031. 1965.-The ability of Chrombacterium violaceum to utilize l-tryptophan for the synthesis of a purple pigment, violacein, served as a basis for the development of a quantitative estimation of this amino acid. The method consists of suspending washed colorless cells of the organism in an agar layer, placing a paper disc impregnated with a tryptophan solution on top of the layer, and allowing the system to incubate. As tryptophan diffuses into the agar, it is converted into violacein, and appears as a zone of striking purple color. Since the diameter of the zone is a function of the amount of tryptophan applied, the amino acid can be quantitatively estimated within the range of 10 to 320 mug per sample with 5.6% standard deviation. The method is fairly specific for free tryptophan, since only indole, indole-3-pyruvic acid, and, to a small degree, anthranilic acid interfere. Other amino acids, tissue homogenates, tryptophan in peptide linkage, or compounds related to this amino acid do not affect its determination. The bacterium does not utilize tryptophan for the synthesis of cellular m...Continue Reading

References

Jul 1, 1956·Archives of Biochemistry and Biophysics·C MITOMAS UDENFRIEND
Aug 1, 1956·Journal of General Microbiology·P H SNEATH
Apr 1, 1957·Archives of Biochemistry and Biophysics·L H FRANK, R D DEMOSS
Feb 1, 1959·Journal of Bacteriology·R D DEMOSS, M E HAPPEL
Sep 1, 1961·The Biochemical Journal·T A SCOTT
Nov 1, 1960·Archives of Biochemistry and Biophysics·A MRSKOS, J TOVAREK
May 1, 1960·Journal of Bacteriology·R D DEMOSS, N R EVANS
Oct 1, 1959·Journal of Bacteriology·R D DEMOSS, N R EVANS
Jan 1, 1964·Analytical Biochemistry·A S INGLIS, I H LEAVIN
Jul 1, 1964·Applied Microbiology·W B SAVCHUCKW L LOCKHART
Nov 30, 1951·Science·R J BARRNETT, A M SELIGMAN

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