Enzymatic Degradation of L-Cystine by Cytoplasmic Particles from Cabbage Leaves

Abstract

THE degradation of cystine by cystathionase preparations from liver¹ and Neurospora² has been reported. A highly purified cystathionase from Neurospora catalysed the cleavage of cystine to pyruvate, ammonia and thiocysteine². L-Cystine was utilized at only 17 per cent of the rate of cystathionine. A second cystathionine cleavage enzyme which utilizes L-cystine at the same rate as cystathionine has recently been found in Neurospora³. We have found that homogenates of cabbage leaves can be fractionated into particulate and soluble cytoplasmic fractions, both possessing a heat-sensitive ability to degrade L-cystine to pyruvate. The two enzymatic activities appear to have different characteristics. The present communication briefly reports on some of the properties of the particulate enzyme.