Partial Purification and Properties of a beta-d-Glucosyltransferase Occurring in Germinating Phaseolus aureus Seeds.

A soluble enzyme that transfers d-glucose from uridine diphosphate d-glucose to low molecular weight hydroxyl compounds has been discovered in germinating mung bean (Phaseolus aureus) seeds and purified 220-fold. Phenol and n-butyl alcohol are the most reactive aceptors examined. The reactivities of various acceptors are largely independant of hydroxyl group acidities or of the electronic properties of the acceptors.

Substrate Activation of beta-(1 --> 3) Glucan Synthetase and Its Effect on the Structure of beta-Glucan Obtained from UDP-d-glucose and Particulate Enzyme of Oat Coleoptiles.

UDP-d-glucose, at a micromolar level in the presence of MgCl(2) and oat (Avena sativa) coleoptile particulate enzyme which contains both beta-(1 --> 3) and beta-(1 --> 4) glucan synthetases, produces glucan with mainly beta-(1 --> 4) glucosyl linkages. An activation of beta-(1 --> 3) glucan synthetase by UDP-d-glucose and a decrease in the formation of beta-(1 --> 3) glucan in the presence of MgCl(2) have been observed. However, at high substrate concentration (>/= 10(-4)m), the activation of beta-(1 --> 3) glucan synthetase is so pronounced that the formation of beta-(1 --> 3) glucosyl linkage predominates in synthesized glucan regardless of the presence of MgCl(2).

Partial Purification and Properties of d-Glucosamine 6-Phosphate N-Acetyltransferase from Phaseolus aureus.

d-Glucosamine-6-P N-acetyltransferase (EC 2.3.1.

The Role of a d-Mannosyl-Lipid as an Intermediate in the Synthesis of Polysaccharide in Phaseolus aureus Seedlings.

Particulate preparations from Phaseolus aureus produce a d-mannosyl-lipid when treated with GDP-d-mannose. This lipid complex appears to be an active d-mannose donor, and some investigators have proposed that its role might be an obligatory intermediate in mannan synthesis of higher plants. When the partially purified d-mannosyl-lipids, isotopically labeled in the d-mannose moiety, were treated with particulate enzymes under a variety of conditions, a negligible amount of material was produced that behaved as a polysaccharide.

Partial Purification and Properties of l-Glutamine d-Fructose 6-Phosphate Amidotransferase from Phaseolus aureus.

l-Glutamine d-fructose 6-phosphate amidotransferase (EC 2.6.1.

Solubilization and Separation of Uridine Diphospho-d-glucose: beta-(1 --> 4) Glucan and Uridine Diphospho-d-glucose:beta-(1 --> 3) Glucan Glucosyltransferases from Coleoptiles of Avena sativa.

The particulate glucan synthetase preparation isolated from a homogenate of oat coleoptiles at 4 C lost 65% of its original activity after 1 day when the UDP-d-glucose substrate concentration was 5 x 10(-7)m to 1.0 x 10(-6)m. Storage of the particulate enzyme at -20 C or in liquid nitrogen did not prevent the enzyme from losing its activity.

Determination of linkages in beta-D-Glucans from Phaseolus aureus by exo-beta-(1 to 3)-D-glucanase.

An alkali-insoluble glucan synthesized from UDP-d-glucose by the particulate enzyme system from Phaseolus aureus is hydrolyzed by a highly purified exo-beta-(1 --> 3)-d-glucanase to d-glucose, to the extent of 91% in 24 hr. The alkali-insoluble glucan from GDP-d-glucose formed by the particulate enzyme system from the same plant which is known to be (from chemical data) a beta-(1 --> 4)-d-glucan (cellulose) is not acted upon by this glucanase.

Biosynthesis of Insoluble Glucans From Uridine-Diphosphate-d-Glucose With Enzyme Preparations From Phaseolus aureus and Lupinus albus.

Particulate, and digitonin-solubilized, enzyme systems from Phaseolus aureus and Lupinus albus catalyze the biosynthesis of aqueous-insoluble glucans from UDP-d-glucose. The digitonin treatment greatly increases the enzymic activity of (per unit protein) both the 34,000g pellet and the supernatant liquid as compared with that of the original particles. Most of the polymer produced (90-95%) is soluble in hot, dilute alkali; the interglucosidic linkages of the alkali-soluble and alkali-insoluble polymers are identical.

Pathway of Uridine Diphosphate N-Acetyl-d-Glucosamine Biosynthesis in Phaseolus aureus.

Studies with extracts obtained from mung beans (Phaseolus aureus) showed that UDP-N-acetyl d-glucosamine is formed from d-fructose 6-phosphate by a series of the following enzymic reactions: [Formula: see text]UDP-N-acetyl-d-glucosamine inhibits the first reaction in the multistep pathway leading to its biosynthesis.

Biosynthesis of Alkali Insoluble Polysaccharide from UDP-d-Glucose with Particulate Enzyme Preparations from Phaseolus aureus.

A particulate enzyme system from Phaseolus aureus seedlings catalyzes the synthesis of alkali insoluble polysaccharide material from UDP-d-glucose. 80 to 90% of the d-glucose units are joined by beta-1,4 linkages, the remainder being combined by beta-1,3 linkages. It is not known whether the material is a single polysaccharide or a mixture.