Characterization of D-cysteine desulfhydrases and D-cysteine-containing compounds in plants

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It is well documented that amino acids, in general, are used in the L-form, and that enzymes involved in their metabolism are stereospecific for the L-enantiomers. However, D-amino acids are found in bacteria, but also in other living organisms as free or conjugated amino acids and as part of peptides. It was also shown that many enzymes are specific for the respective L- or D-form. In bacteria and plants D-cysteine specific desulfhydrase activities were demonstrated catalysing the degradation of D-cysteine to pyruvate, H2S and ammonium. We would like to characterize the function of D-cysteine desulfhydrases from plants, and subsequently the role of D-cysteine and D-cysteine-containing peptides in vivo. D-cysteine might be involved in specific biosynthetic pathways, in protein catabolism and in signalling processes. D-cysteine containing peptides could play a role in plant-pathogen interaction. The metabolism of D-cysteine and D-cysteine-containing peptides will be investigated. In crop plants D-amino acids were found in different percentages. The influence of D-amino acids in general and D-cysteine specifically on human nutrition is not well understood. A reduction of the percentage of D-cysteine might improve plant-based food.