Cleavage of the (1 goes to 3)-2-acetamido-2-deoxy-beta-D-glucopyranosyl linkage present in keratan sulfate. The A and B isoenzymes of human liver hexosaminidase (EC 3.2.1.30)

The disaccharide 2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1 goes to 3)-D-[1-3H]-galactitol, prepared from keratan sulfate, was rapidly hydrolyzed by the A and B isoenzymes of normal human liver hexosaminidase (EC 3.2.1.30), and by the B isoenzyme prepared from the liver of a patient who had died of Tay-Sachs disease. The disaccharide substrate was also hydrolyzed by extracts of normal, cultured-skin fibroblasts, and fibroblasts of patients with Tay-Sachs disease, whereas it was not hydrolyzed by fibroblast extracts of patients with Sandhoff disease. Thus, effective degradation of keratan sulfate, secondary to a defect of the beta subunits present in the A and B isoenzymes of hexosaminidase, may contribute to the appearance of skeletal lesions in patients affected by Sandhoff disease.     

Toward a synthesis of Clostridium butyricum apoferredoxin: Two tetradecapeptides comprising half the sequence (residues 7–20 and 21–34)

The two protected tetradecapeptides Z·Ser·Cys[Bzl(OMe)]·Val·Ser·Cys[Bzl(OMe]·Gly·Ala·Cys[Bzl(OMe)]·Ala·Gly·Glu(OBu^t)· Cys[Bzl(OMe)]·Pro·Val·NH·NH·Boc and Z·Ser·Ala·Ile·Thr·Gln·Gly·Asp(OBu^t)·Thr(Bu^t)·Gln·Phe·Val·Ile·Asp(OBu^t)·Ala·NH·NH·Boc, corresponding to residues 7–20 and 21–34 in the amino acid sequence of Clostridium butyricum apoferredoxin have been synthesized as a first stage in a total synthesis of the apoferredoxin. The former peptide has been deprotected to the tetra-thiol peptide H·Ser·Cys·Val·Ser·Cys·Gly·Ala·Cys·Ala·Gly·Glu·Cys·Pro·Val·NH·NH₂, and two tri-thiol and three di-thiol peptide components of this have also been synthesized for iron-sulfur complexing studies.     

Oligosaccharides containing fucose linked alpha(1-3) and alpha(1-4) to N-acetylglucosamine cause decompaction of mouse morulae

Two- to four-cell and eight-cell mouse embryos were incubated in various fucosylated and unfucosylated oligosaccharides, fucose binding protein, and fucosylated BSA. Compaction at the eight-cell stage was reversed by a mixture containing the oligosaccharides lacto-N-fucopentaose II (80-90%), in which fucose is linked alpha(1-4) to N-acetylglucosamine, and lacto-N-fucopentaose III (10-20%), in which fucose is linked alpha(1-3) to N-acetylglucosamine. Pure lacto-N-fucopentaose III (LNFP III) and 3-fucosyl lactose (containing fucose alpha(1-3)glucose) had a similar effect. All three molecules affected blastocyst formation. Various closely related fucosylated and unfucosylated oligosaccharides did not induce decompaction or inhibit blastocyst formation. The proportion of embryos incubated from the two- to four-cell stage in LNFP II/III which reached the eight-cell stage and formed blastocysts was reduced. Those which formed compact morulae subsequently decompacted. Precompact or early compacting eight-cell embryos incubated in LNFP II/III compacted normally but subsequently decompacted and failed to form blastocysts. Decompaction of eight-cell embryos in LNFP II/III occurred during a specific period of development (80-90 hr post-hCG) and was reversible up to 84-86 hr post-hCG, but not by 92 hr post-hCG. The period of sensitivity to LNFP II/III was associated with the decrease in the ability of calcium-free medium to cause decompaction. It appears that LNFP II/III interferes with a later calcium-independent phase of compaction and we propose that LNFP III and II inhibit an endogenous lectin-saccharide interaction between membranes involved in the stabilization of compaction.     

The synthesis and N.M.R. spectroscopy of derivatives of 6-amino-6-deoxy-D-galactose-6-15N

Derivatives of 6-amino-6-deoxy-D-galactose-6-¹⁵N have been synthesized by reaction of the 6-deoxy-6-iodo (1) or 6-O-p-tolylsulfonyl derivative of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose with potassium phthalimide-¹⁵N. The reaction of 1 also yielded an elimination product, 6-deoxy-1,2:3,4-di-O-isopropylidene-β-L-arabino-hex-5-enopyranose. The structures of the 6-amino-6-deoxy-D-galactose derivatives and their precursors were characterized by proton- and ¹³C-n.m.r. spectroscopy, with confirmation of the ¹³C assignments by selective proton decoupling. Selective broadening of the C-1, C-4, C-5, and C-6 resonances of 6-amino-6-deoxy-1,2:3,4-di-O-isopropylidene-α-D-galactopyranose by low concentrations of cupric ion was observed, and studied by computerized measurements of the ¹³C linewidths. The application of this broadening to ¹³C-spectral assignments of amino sugar derivatives is indicated.     

Some studies on dehydro-d-ascorbic acid 2-(phenylhydrazone)

Reaction of hydroxylamine with d-erythro-2,3-hexodiulosono-1, 4-lactone 2-(phenylhydrazone) (2) gave the 3-oxime 2-(phenylhydrazone) (3). On boiling with acetic anhydride, 3 gave 4-(d-erythro-2,3-diacetoxy-l-hydroxypropyl)-2-phenyl-1,2, 3-triazoIe-5-carboxylic acid 5,1′-lactone. Compound 3 was also converted into the related, unacetylated 2-(p-bromophenyl)triazole with bromine. Treatment of 2 with boiling acetic anhydride gave an optically inactive, olefinic compound, assigned the structure 4-(2-acetoxyethylidene)-4-hydroxy-2,3-dioxobutano-1,4-lactone 2-(phenylhydrazone). The 2-(phenylhydrazone) 2 gave the corresponding 2,3-bis(phenylhydrazone) on condensation with phenylhydrazine.     

Insulin-like,and insulin-antagonistic,carbohydrate derivatives. The synthesis of aryl and aralkyl d-mannopyranosides and 1-thio-d-mannopyranosides

A number of novel, aryl and aralkyl d-mannopyranosides and 1-thio-d-mannopyranosides were synthesized for evaluation of insulin-like and insulin-antagonistic properties. The substituted-phenyl α-d-mannopyranosides were prepared by the general procedure of Helferich and Schmitz-Hillebrecht, the substituted-phenyl 1-thio-α-d-mannopyranosides by a method corresponding to the Michael synthesis of aromatic glycosides, and the aralkyl 1-thio-α-d-mannopyranosides by aralkylation of 2,3,4,6-tetra-O-acetyl-1-thio-α-d-mannopyranose (15) and subsequent O-deacetylation. Compound 15 was obtained by basic cleavage of the amidino group in 2-S-(tetra-O-acetyl-α-d-mannopyranosyl)-2-thiopseudourea hydrobromide, the product of the reaction of tetra-O-acetyl-α-d-mannosyl bromide with thiourea. Benzyl 1-thio-β-d-mannopyranoside, obtained by reaction of the sodium salt of 1-thio-β-d-mannopyranose with α-bromotoluene, and benzyl 1-thio-α-l-mannopyranoside were also synthesized, in order to assess the stereospecificity of the biological activities measured.     

Equilibria of the anomeric and ring forms of ammonium 3-deoxy-d-manno-octulosonate in deuterium oxide

The tautomeric composition of a solution of ammonium 3-deoxy-d-manno-octulosonate (KDO, 1a) in D₂O at 28° was assessed by means of ¹³ C-F.t.-n.m.r. spectroscopy. The results revealed the presence of 6?0 and 11 % of the α and β anomers of the pyranose, and 20 and 9 % of the two furanoses, and suggested, but did not unequivocally prove, that the major furanose form is the α anomer. To facilitate interpretation of the spectral results for 1, ammonium 3,5-dideoxy-d-arabino(or ribo)-octulosonate (3a) was prepared by the reaction of 5-deoxy-d-erythro-pentose with sodium oxalacetate at pH 11. A chromatographically homogeneous, noncrystalline sample of 3 was obtained by lyophilization, and characterized as its (4-nitrophenyl)hydrazone (m.p. 162-163°). The ¹³C-n.m.r. spectrum of a solution of 3a in D₂O revealed it to be substantially all in the α-pyranose form. No signals were obtained for the possible 1,4-lactone of 3. As the 1,5-lactone and furanose forms are impossible for 3, it exhibited no signals analogous to those attributed to furanoid 1. On the basis of these results for 3, the two lactone forms of 1 were excluded from consideration, and the three pairs of ¹³C-n.m.r. signals observed at ≈45, 86, and 104 p.p.m. were assigned to the furanose forms of 1.     

Cerheptaric Acid, A new lactone-forming acid isolated from cereus peruvianus (L.) mill

A systematic study of the acid-catalyzed fusion-reaction is reported. The influence of the nature and stereochemistry of the d-aldopentofuranose and the effect of the substituent at C-2 have been investigated by using indazole as a model heterocycle. The results obtained show that the nature and stereochemistry of the starting, per-O-acetylated d-aldopentofuranose have no significant effect upon the product distribution of the acid-catalyzed fusion-reaction. The use of a sugar lacking a participating group at C-2 showed, however, that the absence of participation increases the ratio of cis-1′,2′-nucleosides, and the mechanism involved is discussed. In all cases, the results indicated that the distribution of the products is determined by their relative, thermodynamic stabilities.