Methyl jS-D-galactopyranoside

Selective replacement of primary hydroxyl groups in carbohydrates by iodine atoms has been achieved by using the Rydon reagent, namely, methyltriphenoxyphosphonium iodide.368 Treatment of methyl 3,4-O-isopropylidene-jS-D-galactopyranoside with the phosphonium salt in benzene for 48 hours at room temperature yielded 60% of the 6-deoxy-6-iodo derivative,369 and reaction of thymidine, uridine, and 2,2 -anhydrouridine in N,N-dimethylformamide afforded 5 -deoxy-5 -iodo derivatives in yields of 63, 65, and 31%, respectively.370... 

Galactopyranoside, methyl a-D-benzoylation of, 250 sulfonylation of, 247 —, methyl /3-D-, sulfonylation of, 248 —, methyl 3,6-anhydro-2,4-di-0-methyl-jS-D-, 270... 

Glycosides and Simple Derivatives Thereof. — Methyl jS-D-arabinopyranoside, methyl a- and -D-galactopyranoside (n.d.), methyl 3,6-dideoxy-j3-D-riho-... 

Methyl 2-0- 3-D-xylopyranosyl-D-galactopyranuronate, a pseudoaldobiouronic ester, has been synthesized by a route in which the key step was the condensation of methyl (benzyl 3,4-0-isopropylidene-jS-D-galactopyranosid)uronate with... 

Scheme 24. Partial fragmentation of methyl 2,3,4-tri-0-methyl-6-0-(methyl 2,3,4-tri-0-methyl- -D-gluoopyranosyl-uronate)-jS-D-galactopyranoside, 24.

These crystal-structure analyses are concerned with the following molecules o-D-glucopyranose monohydrate/ D-xylopyranose/ methyl yS-D-xylopyranoside, di-jS-n-fructopyranose-strontium chloride trihydrate, cellobiose (independent determination), D-glucaric acid, D-galactonic acid, methyl a-D-lyxofuranoside, /3-D-lyxopyranose, methyl 3,4,6-tri-0 - acetyl - 2 - (chloromercuri) - 2 - deoxy - j3 - d - glucopyranoside, D-glu-copyranosyl (potassium sodium phosphate) tetrahydrate," and methyl 6-bromo-6-deoxy-a-D-galactopyranoside. ... 

The site of attachment to E. coli jS-D-galactosidase of the active site-directed inhibitor methyl 4-nitrophenyltriazine j3-D-galactopyranoside has been determined. When the enzyme was completely inactivated, 1 mole of the methyl D-galactopyranoside group was bound per mole of monomer with retention of the tetrameric structure. After reactions with the [ C]methyl version of the reagent, labelled peptides were isolated and analysed. The radioactive label was found to be covalently bound to L-methionine residue 500. 

Human placental jS-D-acetamidodeoxyhexosidases A and B exhibited maximum activity against 4-methylumbelliferyl 2-acetamido-2-deoxy-j5-D-galactopyranoside at pH 4.4, and the kinetics of the enzymes have been examined in detail. On disc electrophoresis in the presence of sodium dodecyl sulphate, the 5-carboxy-methylated B isoenzyme (mol. wt. 1.0—1.4 x 10 ) gave one principal subunit (mol. wt. 1.7—1.8 X 10 ), whereas the A isoenzyme (mol. wt. 1.0—1.4 x 10 ) yielded a subunit of similar size and two additional protein bands (mol. wt. 3.5 X 10 and 5.5 x 10 ). The amino-acid compositions and iV-termini of the subunits were compared. 

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