Interspecific Variation in Activity and Regulation of Leaf Sucrose Phosphate Synthetase

摘要: Summary Sucrose-P synthetase was extracted and assayed in crude preparations from leaves of various species that differ leaf starch accumulation. Magnesium required the grinding medium for enzyme stability assay enzymic activity. The enzyme, tobacco (Nicotiana tabacum L.), peas (Pisum sativum beans (Phaseolus vulgaris L.) peanuts (Arachis hypogaea had relatively low activity on a chlorophyll basis (6.8 to 12.9,umol product/mg h), its inhibited by 50 mM sucrose (30 100 Ofo inhibition). In contrast, sucrose-P extracts wheat (Tritium aestivum barley (Hordeum vulgare spinach (Spinacea oleracea generally higher (10 12.5,µmol/mg h) not sucrose. Activity synthase different variable (0 3.4 ,umol!mg Chl much lower than synthetase. Leaf content negatively correlated (r = -0.94) with extracts. results suggested may be ratelimiting photosynthetic formation and, hence, account differences Sucrose inhibition this some also provide biochemical explanation increased accumulation when translocation is reduced