Resolution of mixtures of sugars by means of partition chromatography on columns: resolution of a mixture of the four aldopentoses and 2-deoxyribose and of certain hexoses

The determination of glucosamine and galactosamine in some glycoproteins by radioisotope dilution

1. The principle of radioisotope dilution was applied on a semi-micro scale to the determination of glucosamine and galactosamine in some glycoproteins, such as immunoglobulins, a urinary glycoprotein and blood-group-specific substances. 2. The glycoprotein was hydrolysed in the presence of [1-(14)C]glucosamine or [1-(14)C]galactosamine or both. The amino sugars were made to react with naphthyl isothiocyanate and the products formed were isolated by the method of Scott (1962). The specific radioactivities determined from liquid-scintillation counting and the extinction at 240mmu or 222mmu were used to calculate the content of amino sugars in the protein analysed. 3. Where the values could be compared with those found by other workers, differences were in general not very great. The advantages of the method are that high concentrations of acid can be employed and undesirable side reactions, which may occur with the free sugars, do not affect the results. A potential source of error of the method is discussed.

The estimation of galactose, mannose and fucose in glycoproteins by radioisotope dilution

1. The principle of radioisotope dilution, as used previously for the estimation of mannose in egg albumin, was applied on a semi-micro scale to the estimation of fucose, mannose and galactose in some glycoproteins. The sugars were separated by partition chromatography on columns of Celite 545. 2. The release of mannose from egg albumin in 2n-hydrochloric acid at 100 degrees after various times was determined by the radioisotope-dilution method and found to have a half-time of 7min. 3. The destruction of mannose in 2n-hydrochloric acid after 3hr. at 100 degrees was found to be small if air was excluded. The destruction was slightly increased by the presence of lysozyme containing tryptophan in an amount equimolar with the mannose. The same amount of free tryptophan caused considerable loss of mannose. 4. Analytical values are reported for the non-amino sugar contents of egg albumin, rabbit gamma-globulin and some samples of blood-group-specific substances. The values found were similar to the most reliable estimates published previously.