Glucose mung bean

Affinity Labeling with UDP-pyridoxal. Read and Delmer (21) utilized the substrate analog UDP-pyridoxal to inhibit mung bean glucan synthase. This affinity label inhibited glucan synthase at micromolar levels and inhibition was protected against with UDP-glucose. A 42 kD polypeptide could be labelled with [3H]UDP-pyridoxal. 

Early reports of such an enzyme system, tightly bound and occurring in a particulate fraction of mung bean, were made by Hassid and associates.292,293 The glycosyl donor was reported to be GDP-D-glucose and the product was characterized as a / -(l— 4)-linked D-glucan,292,293 Liu and Hassid294 solubilized, and partially purified, this enzyme. 

Hassid and coworkers293 reported that this mung-bean enzyme-system catalyzes the incorporation of D-glucose from GDP-D-glucose into a polysaccharide having the characteristics of cellulose and that, in the presence of GDP-D-mannose, this incorporation was stimulated. The same enzyme-system, when provided with GDP-D-mannose as the sole substrate, catalyzed the incorporation of GDP-D-mannose into a glucoman-... 

Brummond and Gibbons304 demonstrated the presence, in higher plants, of enzymes that utilize UDP-D-glucose to produce a cellulose-like polymer, and Hassid and coworkers305 separately reported in mung bean a similar enzyme system in which 80-90% of the product consisted of... 

It has also been shown that mung beans, peas, and other plants contain a pyrophosphorylase which forms GDP-D-glucose from a-D-glucose 1-P and GTP. Based on the data obtained with enzymic plant preparations, we proposed the following mechanism for cellulose synthesis ... 

In 1975, Franz150 reported that incubation of mung-bean membrane-preparations with radioactive UDP-glucose resulted in the production of a variety of polymeric products, one of which was identified as a glucoprotein. The radioactivity associated with this presumed glucoprotein could be solubilized by treatment of the alkali-insoluble prod-... 

Villemez and coworkers have also reported that an enzyme preparation from mung beans could produce an alkali-insoluble D-glucan from UDP-D-glucose that contains both )8-D-(l — 3)- and )8-D-(l — 4)-links. However, it was not determined whether the product was a mixture of cellulose and callose or a single polysaccharide having mixed linkages. 

It has been shown that soluble, enzyme preparations from mung beans, peas, and other plants show pyrophosphorylase activity, and can form GDP-D-glucose from GTP and a-D-glucosyl phosphate. These enzyme preparations also contain various carbohydrate compounds, including small proportions of cellulose, that could act as acceptor. Therefore, it was postulated that cellulose in higher plants is formed through the following reactions. ... 

Whereas the results of Ordin and Hall with enzyme preparations from oat coleoptiles and UDP-D-glucose as substrate could be substantiated, a later investigation by Flowers and coworkers who used chemical methods showed that particulate enzyme preparations from mung beans behaved differentiy from those previously reported. ... 

Examination of the polymers synthesized by particulate enzyme preparations from mung beans Phaseolus aureus) and those of the Lupinus albus variety, by use of GDP-D-glucose and UDP-D-glucose, showed that a (1 4)-/3-D-glucan is formed only from GDP-D-glu-cose, " and a (1 3)-/3-D-glucan when UDP-D-glucose is the substrate. 

On the other hand, when GDP-D-glucose was used as the substrate, both the particulate and the digitonin-solubilized enzyme systems from mung beans and from Lupinus albus yielded only (1 — 4)-/3-D-gIucan (cellulose), practically all insoluble. 

Experiments with particulate enzyme preparations from mung beans (Phaseolus aureus) and Lupinus albus beans showed that incorporation of radioactive D-glucose from UDP-D-glucose- C into the glucan increased with increase of concentration of UDP-d-glucose- C substrate in the incubation mixture, and reached a maximum of 50% of the substrate radioactivity incorporated. ... 

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