gamma-Carboxyglutamic acid content in human kidney and placenta

The presence of gamma-carboxyglutamate-containing proteins in human placenta and kidney has been examined. For the detection of these proteins gamma-carboxyglutamate content of alkaline hydrolysates of tissue homogenates has been determined. gamma-Carboxyglutamic acid was identified by amino acid analysis of alkaline and acid hydrolysates. In kidney a gamma-carboxyglutamate content of 4 nmol/mg of protein has been found, however in placenta this amino acid was undetectable (less than 0.1 nmol/mg of protein).