A glucomannan from Arum korolkovii
SummaryA glucomannan has been isolated from the tubers ofArum korolkovii Regel. It has been shown that the polysaccharide contains O-acetyl groups and consists mainly of (1 → 4)-β-linked aldohexopyranose units of glucose and mannose in a ratio of 1:1.6. The nonreducing ends of the glucomannan are glucose residues, and branching is localized at C2 and C3 of mannose.
Acetyl Groups in Native Glucomannan from Easter Lily Bulbs
Glucomannan has been extracted with water from several plants and purified via a copper complex using Fehling's solution.1-8) It is well-known, however, that the resulting polysaccharide becomes insoluble in water. This is the reason why biochemical research on polysaccharides is difficult, and it seems doubtful whether the insoluble polysaccharide is native. In this report we have attempted to compare the glucomannan compounds extracted and purified by two different procedures from Easter lily bulbs and to investigate the cause of the insolubility. Glucomannan was extracted from commercial bulbs of Easter lily (Lilium longiflorum Thunb var. "Georgia." All bulbs were at the dormant stage.) by the following two procedures. One was the conventional method with Fehling's solution (yield; 1.78% from fresh scales)'1 The other was a procedure not involving Fehling's solution, as described below. Fresh scales (20 g) were homogenized in a mortar with 20 volumes of dist. water. After centrifugation, an equal volume of ethanol was added to the supernatant. The precipitate was dis solved into 100 ml of dist. water. The solution, after dialysis against 0.01 M phosphate buffer (pH 7.3) or dist. water, was applied to a DEAE-cellulose column
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.