Transsulfuration by human long term lymphoid lines. Normal and cystathionase-deficient cells

Long term human lymphoid cells from normal subjects were able to convert [35S]homocysteine to [35S]-cystine. The labeled cystine was found incorporated into proteins. Cells cultured from a patient with vitamin B6-unresponsive cystathioninuria, which contain no measurable cystathionase activity, were unable to perform this conversion. This is the first direct demonstration of transsulfuration by diploid cells in culture.