The function of myo-inositol in the biosynthesis of raffinose. Purification and characterization of galactinol:sucrose 6-galactosyltransferase from Vicia faba seeds

Physiology and biosynthesis of lychnose in Cerastium arvense

The synthesis and accumulation of lychnose and isolychnose in leaves of Cerastium arvense during late fall and winter were shown to be controlled mainly by the temperature regime, while the photoperiodic regime had only a quantitative effect. Labelled lychnose and isolychnose were formed from [(14)C]raffinose in a cell-free enzyme preparation of leaves of Cerastium arvense in accordance with the equation: raffinose+raffinose →(iso-)lychnose+sucrose.

myo-Inositol metabolism in germinating wheat

During imbibition, exogenous myo-inositol (MI) was readily introduced into the free MI pool of germinating wheat (Triticum aestivum L.). Maximum uptake, 70 μg per caryopsis or 1.5 mg g(-1) of caryopsis, was reached at 0.05 M MI. Movement of free MI within the germinating caryopsis was traced with [2-(3)H]MI by two procedures, uptake by imbibition and injection into softened endosperm. The former procedure was useful during initial stages of germination; the latter provided a means of tracing the metabolic fate of MI generated by hydrolysis of phytate during mobilization of reserves within the caryopsis. In both procedures, the bulk of the added label was transferred to the seedling where it appeared in uronosyl and pentosyl units of 80% ethanol-insoluble polysaccharides, 2-O, C-Methylene-MI, an inhibitor of the MI oxidation pathway, blocked the utilization of [2-(3)H]MI as well as D-[1(14)C]glucose for biogenesis of pentose-and uronic-acid-containing polysaccharides.

[Role of some intermediates of galactosylglycerol metabolism in the osmotic balance in Ochromonas malhamensis]

The osmotic balance in Ochromonas malhamensis Pringsheim is achieved mainly by formation or degradation of α-galactosylglycerol (isofloridoside). The time course of the incorporation of radioactivity from (14)CO2 under conditions of high isofloridoside production suggests (Fig. 1) that isofloridoside-phosphate is indeed a precursor in the formation of isofloridoside. To study changes in relative pool sizes of intermediates cell constituents were prelabelled by assimilation of (14)CO2. Upon an increase of osmotic pressure the concentration of isofloridoside-phosphate increases rather rapidly sustaining the above conclusion. The final rate of isofloridoside formation, however, is reached long before the final concentration of the precursor is established (Fig. 2). On a decrease of osmotic pressure isofloridoside-phosphate concentration first increases and than decreases (Fig. 3). The data indicate that control of isofloridoside formation might occur at least at two steps: at the transfer of galactose to glycero-3-phosphate as well as at the dephosphorylation of isofloridoside-phosphate. Under conditions resulting in increased isofloridoside degradation the pool size of free glycerol is rapidly increased about ten fold, whereas the pool of free galactose responds to a far smaller extent (Fig. 3). This might indicate the operation of a transgalactosidase or an α-galactosidase in cooperation with an unusually potent galactose kinase.