Exogenous l-tyrosine metabolism and dhurrin turnover in sorghum seedlings

Bough, W.A. and Gander, J.E. (1971) Exogenous l-tyrosine metabolism and dhurrin turnover in sorghum seedlings. Phytochemistry, 10 (1). pp. 67-77.

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Abstract

It was shown that dhurrin (p-hydroxymandelonitrile-β-glucopyranoside) was actively metabolized by etiolated Sorghum vulgare seedlings. A turnover rate of about 0·05 μmole/hr was found in seedlings containing 1·0 μmole dhurrin/shoot. These studies showed a logarithmic decrease in the specific activity of 14C labelled dhurrin when unlabelled l-tyrosine was administered to the seedlings. The increase in specific activity of dhurrin was shown to be a logarithmic function of time when seedlings were administered [2-14C]-l-tyrosine. In addition, it was concluded that a major fraction of the dhurrin in the seedlings was derived from endogenous sources rather than from exogenously supplied l-tyrosine. Sorghum seedlings were shown to metabolize [1-14C]-, [2-14C]-, [3-14C]-, and [U-14C]-l-tyrosine to 14CO2. Based on the time course of 14CO2 released from l-tyrosine labelled in carbon atom 1, 2 or 3 as compared to uniformly labelled l-tyrosine, the data suggest that sorghum seedlings catabolized a portion of the aromatic ring carbon atoms to 14CO2. The dhurrin present 50 hr after administering [2-14C]-l-tyrosine represented only 3% of the 14C found in the various extracts, residues and CO2. A procedure for isolating dhurrin from perchloric acid extracts is described.

Item Type:	Article
Author Affiliation:	Department of Biochemistry, College of Biological Sciences, University of Minnesota, St. Paul, Minnesota 55101, U.S.A.
Subjects:	Crop Improvement
Divisions:	Sorghum
Depositing User:	Mr. SanatKumar Behera
Date Deposited:	23 May 2012 07:46
Last Modified:	23 May 2012 07:46
Official URL:	http://dx.doi.org/10.1016/S0031-9422(00)90252-8
URI:	http://eprints.icrisat.ac.in/id/eprint/5650

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