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. 1985 Jun;78(2):285–290. doi: 10.1104/pp.78.2.285

Subcellular and Developmental Distribution of β-Cyanoalanine Synthase in Barley Leaves 1

Eve Syrkin Wurtele 1,2, Basil J Nikolau 1,3, Eric E Conn 1
PMCID: PMC1064720  PMID: 16664231

Abstract

The subcellular and developmental distribution of β-cyanoalanine synthase (EC 4.4.1.9), which catalyzes the reaction between cysteine and HCN to form β-cyanoalanine and H2S, were investigated in barley (Hordeum vulgare) leaves. Total leaf activity was 1.1 micromoles per minute per gram fresh weight. Sucrose density gradients of lysed mesophyll protoplasts of barley revealed the exclusive or predominant localization of β-cyanoalanine synthase in the mitochondria. The enzyme was absent from both vacuole and chloroplast fractions.

β-Cyanoalanine synthase activity was distributed over the entire length of the barley leaf. Activity was dependent on the developmental stage, with a 3.5-fold higher activity in the oldest (apical) compared to the youngest (basal) parts of the leaf. The corresponding difference in activity for mesophyll protoplasts isolated from these parts was 7.5-fold. In younger leaf seagments, the nonchlorophyllous tissues accounted for up to 70% of the total β-cyanoalanine synthase activity. These results are discussed with reference to the formation of HCN as a substrate in barley leaves.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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