Trehalose periodate oxidation

The reaction of these aldehydes, derived from periodate oxidation, with carbonyl reagents has also been investigated. Studies 147 148 were made on oxidized laminarin, a (1 —> 3)-linked polysaccharide, in which only the terminal residues had been oxidized. The addition of phenylhydrazine acetate detached the remainder of the terminal residue as glyoxal phenyl-osazone. When the aldehydic compounds derived from the periodate oxidation of raffinose and trehalose818a were reacted with p-nitrophenylhydrazine, the authors were surprised to find that one molecule of oxidized raffinose, containing six aldehydic functions, reacts with only three molecules of the reagent, and that the four aldehydic functions of the oxidized trehalose molecule react with only two. The reactions of periodate-oxidized carbo-... 

Methylation and subsequent hydrolysis of a,a-trehalose or /3,/3-trehalose produces two moles of 2,3,4,6-tetra O-methyl-D-glucose. Furthermore, methylation of a,a-trehalose 6,6 -dimycolate (see Section II, 2) and saponification of the resulting product to give hexa-0-methyl-a,a-trehalose, followed by hydrolysis, affords 2,3,4-tri-O-methyl-D-glucose (identified by paper chromatography and periodate oxidation). 

The pH optimum for the fermentation of a,a-trehalose by living yeast differs from that of n-glucose fermentation, being narrow at a pH of about 5. This optimum coincides with that of brewers -yeast trehalase and indicates that hydrolytic splitting of the a,a-trehalose molecule may precede fermentation of a,a-trehalose. Bakers yeast trehalase is less stable than brewers yeast trehalase. Courtois and Valentino showed that the tetraaldehyde produced by the periodate oxidation of a,a-tre-halose is not attacked by trehalase. On the other hand, Helferich and Stryk showed that 6-0-(methylsulfonyl)-a,a-trehalose is attacked. Hydrolysis of a,a-trehalose by almond emulsin took place to the extent of 27%, and of the monomesyl ester to the extent of 15.5%, after 6,120 minutes. The corresponding figures for yeast extract were 12.1% and 8.3%, respectively, after 7,200 minutes. 

Very successful experiments were carried out on the oxidation of sucrose, one mole of which needs three moles of periodic acid, with the formation of one mole each of formic acid and a tetraaldehyde. The latter is oxidized by bromine to a tetracarboxylic acid subsequent acid hydrolysis of the oxygen bridges affords a mixture of acids, all of which were isolated and identified. These results brought in 1943 a confirmation of the structure of sucrose which was discussed, and which gained the approval of C. S. Hudson who, before that, was a little doubtful about the furanoid form of the D-fructosyl group. Similar work was done later with trehalose. In the same way, J. . Courtois obtained confirmation of the structure of raffinose, and established that of stachyose. 

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