LECTIN AND ALLIINASE ARE THE PREDOMINANT PROTEINS IN NECTAR FROM LEEK(ALLIUM-PORRUM L.) FLOWERS

Analysis of nectar from leek (allium porrum) flowers by SDS-PAGE revea led the presence of two major polypeptide bands of 50 kDa and 13 kDa, respectively. Using a combination of agglutination tests, enzyme assay s and N-terminal sequencing, the polypeptides have been identified as subunits of alliin lyase (alliinase, EC 4.4.1.4) and mannose-binding l ectin, respectively. The latter protein is particularly abundant since it represents about 75% of the total nectar protein. Honey produced b y bees foraging on flowering leek plants still contains biologically a ctive lectin and alliinase. However, the levels df both proteins are s trongly reduced as compared to those in the original nectar. It is evi dent, therefore, that the lectin as well as the alliinase are inactiva ted/degraded during the conversion of nectar into honey.