A CHEMICAL PROCEDURE FOR DETERMINATION OF THE C¹⁴DISTRIBUTION IN SOME LABELLED CARBOHYDRATES

Abstract

A chemical procedure for the determination of the labelling in the terminal carbon atoms of some unsubstituted carbohydrates using 20 mg of material is described. The procedure has been tested on D -g l u~~~e -l -C~' , ~-glucose-6-C'~, D -~~u c o s~-~-C " , and D-glucuronolactone-6-CI4 with satisfactory results.A procedure based on the work of Smith el al. for the degradation of hesoses via the methyl glucopyranosides is described and has been applied to D-glucose-1-C14 and ~-glucose-6-C'4 with satisfactory results. These procedures have been designed to give barium carbonate as the final product in each determination. INTRODUCTIONThere are many procedures for determining CL4 distributioil in carbohydrates described in the literature (1-I&), but of these oilly two afford a conlplete determination of the labelliilg on a nlillimole scale (11, 13). The renzainder either require large amounts of material or do not give the labelliilg in all of the carbon atoms. Guilsalus and Gibbs have described a fermentation procedure with Le~iconosfoc mesenteroide~ (11) for the degradation of glucose and Altermatt, Blacl;wood, and Neish (12) have extended the method to the degradation of xylose. Although this procedure yields satisfactor!. results it is limited to those sugars which the organisin lvill fernzent. Boothroyd, Brolvn, Thorn, and Neish have described chemical procedures for the deter~nillatioll of the C1" labelling in glucose (13) and xylose (14) (see also 10). This method is applicable to inally sugars.A lilnitation to the methods available for radioactive degradation procedures is the type of counting apparatus available. If counting of bariuin carbonate plates is the only method available then the combustion of large molecules, such as dimedone and phenylhydrazone derivatives, is not always suitable, since the labelled moiety beconles diluted with large quantities of unlabelled carbon material.The first part of this paper describes a q net hod by which the CL4 labelling in the terlninal positioil of any unsubstituted carbohydrate may be determined on a lniniinurn of inaterial (20 ing). This quantity is the amount required to give 30 mg of barium carbonate for each of the three determinations involved.The sodiu~n inetaperiodate oxidation of sugars has (16, 17) been extensively studied in this (15) and other laboratories. It has been shown that colnplete oxidation of an aldohexose to 5 inoles of formic acid (C 1-5) and 1 lnole of fornlaldehyde (C-6) talies place rapidly at pH 8.0 (15) (phosphate buffer). I-Iough et al. (17) have shown that the oxidation of glucuronic acid proceeds sinoothly to give 1 inole of carbon dioxide (C-6) and 5 ~noles of for~nic (C 1-5) a t p1-I 3.6 (acetate buffer). The borohydride reduction of oligosaccharides and subsequent metaperiodate oxidation carried out in sit11 without isolatioil of the intermediatory glycitol derivative has been studied (18). These methods \vhen applied to inonosaccl~arides gave a method for determining the labelling in the terininal carbon atoms.The speci...

The biosynthesis of streptomycin. The origin of the C-formyl group of streptose

“…Radioactivity in glucose produced by the above procedure should ideally be confined to C-1 and C-3, and should be equally divided between them. To check the distribution of radioactivity in the product, a sample was degraded by an adaptation of the method of Abercrombie & Jones (1960). First, 0-1g.…”

“…of methyl OC-D-[14C]glucoside was oxidized with sodium metaperiodate and the resulting formic acid and dialdehyde were separated as described by Abercrombie & Jones (1960). The formic acid (derived from C-3 of glucose) was purified by steam-distillation as described above for the formic acid from streptomycin.…”

“…The formic acid (derived from C-3 of glucose) was purified by steam-distillation as described above for the formic acid from streptomycin. The dialdehyde was reduced with sodium borohydride, hydrolysed to glycerol and glycolaldehyde, and the glycolaldehyde was reduced to ethylene glycol (Abercrombie & Jones, 1960). The solution was treated with an excess of Amberlite IR-120 (H+ form) resin and repeatedly evaporated under reduced pressure with methanol to remove boric acid.…”