The kinetics of glucose transport in a number of different mutants of Saccharomyces cerevisiae with multiple deletions in the glucose transporter gene family were determined. The deletions led to differences in maximal rate and affinity for glucose uptake by the cells, dependent on the growth conditions. At the same time, there were changes in glucose repression, as determined by expression of ...

The reducing sugar content of sugar beet (Beta vulgaris L.) roots increased during 30 days of storage at 21 C and 160 days at 5 C as a result of an increase in acid invertase activity. Sucrose synthetase and neutral invertase activities were high at harvest but declined during storage, thus showing no relationship with postharvest reducing sugar accumulation in sugar beet roots. Acid alpha-gluc...

Activation by orthophosphate of a plant invertase from root nodules of Lupinus luteus L. has been demonstrated. The activation affects an increase in maximum velocity (V(max)) of the reaction. Activation was also achieved with a number of similar anions and it has been possible to infer a broad classification of anions capable of serving as activators. The possibility of orthophosphate activati...

Male-sterile plants are used in hybrid breeding as well as for gene confinement for genetically modified plants in field trials and agricultural production. Apart from naturally occurring mutations leading to male sterility, biotechnology has added new possibilities for obtaining male-sterile plants, although so far only one system is used in practical breeding due to limitations in propagating...

Cold storage of tubers of potato (Solanum tuberosum L.) compromises tuber quality in many cultivars by the accumulation of hexose sugars in a process called cold-induced sweetening. This is caused by the breakdown of starch to sucrose, which is cleaved to glucose and fructose by vacuolar acid invertase. During processing of affected tubers, the high temperatures involved in baking and frying ca...

Three soluble isoforms of invertase (8-fructofuranosidase; EC 3.2.1.26) were purified from 7-d-old primary leaves of barley (Hordeum vurgare 1.). lnvertase I, a monomeric protein of 64 kD, was purified to apparent homogeneity as shown by sodium dodecylsulfate-polyacrylamide gel electrophoresis. lnvertases IIA and IIB, multimeric proteins with molecular masses of 116 and 155 kD, were purified 78...

Plant cell wall invertases and fructan exohydrolases (FEHs) are very closely related enzymes at the molecular and structural level (family 32 of glycoside hydrolases) but they are functionally different and are believed to fulfill distinct roles in plants. Invertases preferentially hydrolyze the Glc-Fru linkage in sucrose while plant FEHs have no invertase activity and only split terminal Fru-F...

Excision of developing potato (Solanum tuberosum L.) tubers from the mother plant, followed by storage at 10 degrees C, resulted in a rapid, substantial decrease in sucrose synthase activity and considerable increases in hexose content and acid invertase activity. A comparison of the response of three genotypes, known to accumulate different quantities of hexoses in storage, showed that both su...