Portal de Periódicos da CAPES

Presence of alliinase in isolated vacuoles and of alkyl cysteine sulphoxides in the cytoplasm of bulbs of onion (Allium cepa)

1981; Elsevier BV; Volume: 22; Issue: 2 Linguagem: Inglês

10.1016/0304-4211(81)90139-5

1878-2310

Jane E. Lancaster, H. A. COLLIN,

Nitrogen and Sulfur Effects on Brassica

Protoplasts were isolated from the inner scales of mature onion bulbs, then the vacuoles liberated from the protoplasts by gentle osmotic shock. Protoplasts and vacuoles were compared for alliinase activity (alliin alkylsulphenate-lyase, EC 4.4.1.4). The vacuoles contained alliinase in amounts which account for the alliinase found in protoplasts. Both vacuoles and protoplasts were analysed for S-alkyl substituted cysteine sulphoxides by electrophoresis-thin-layer chromatography (TLC). Whereas the vacuoles contained negligible amounts of alkyl cysteine sulphoxides, the cytoplasm of the protoplasts contained a considerable amount of alkyl cysteine sulphoxides. It is concluded that alliinase and alkyl cysteine sulphoxides are prevented from acting in the intact protoplast by compartmentation of the alliinase in the vacuoles and alkyl cysteine sulphoxides in the cytoplasm.