Lipids periodate oxidation

Periodate-oxidize a liposome suspension containing glycolipid components according to Section 2 (this chapter). Adjust the concentration of total lipid to about 5mg/ml. 

Finally, Droge and coworkers26 showed that the 2-aminoethyl phosphate-substituted KDO group is the lateral KDO unit of the branched trisaccharide (see Fig. 7), as follows. LPS from Salmonella minnesota mR3 was subjected to periodate oxidation. This sample, together with a control that had not been oxidized, was then mildly hydrolyzed with acid (pH = 3.4) during 1 h at 100°. Following removal of lipid A, both samples were analyzed by gel-filtration on Sephadex G-10, and paper electrophoresis. As expected, the ninhydrin-positive material obtained from the control sample was identical with KDO 7-(2-aminoethyl phosphate) (17) as previously identified. This spot was absent from the periodate-treated sample. Instead, an almost neutral, ninhydrin-positive spot was observed. This material (compound 26) was eluted, subjected to reduction with sodium [3H]borohydride, and hydrolyzed under strongly acidic conditions (see Scheme 11). Fol-... 

For the analysis of fatty acids amide-linked to GlcN(I), several chemical degradation procedures are available. One comprises periodate oxidation of 0-deacylated and 2H-reducedlipid A (lipid A-OH ). Following permethyl-ation, g.l.c.-m.s. analysis revealed a 2-deoxy-1 -deuterio-1,3-di-O-methyl-2-(iV-methyl-3-methoxyacylamido)glycerol derivative in which the amide-finked fatty acid at GlcN(I) was identified as 14 0(3-OH) in B. pertussis (93), and as 16 0(3-OH) and 18 0(3-OH) in R. trifolii 81). 

To determine the position of glycosidic bonds in glycosphingolipids, periodate oxidation and methylation are widely used. A characteristic feature of the periodate oxidation of glycosphingolipids is the stability, to oxidation under mild conditions,179 of the D-glucose residue that is located at the beginning of the carbohydrate chain and substituted at 0-4 this seems to be associated with steric hindrance caused by the close location of the lipid moiety. 

The readily available [77, 78] l,6-di-0-benzoyl-3,4-0-benzylidene-2,5-0-methy-lene-D-mannitol has been converted [79] into the benzyl ether (60), which on periodate oxidation and borohydride reduction gives the methylene acetal (61) which readily gives 1 -O-benzyl-L-glycerol for use in lipid synthesis. The acyl derivative (62) has been used [80] in glycolipid synthesis by glycosidation of the hydroxyl group. 

Fig. (10). Agar diffusion of different proteins and a lipid conjugated with lactose against anti-lactose antibodies (well L) and against anti-BSA antibodies (Well BS) wells 1-6 contained Lac-poly, Lac-BSA, Lac-sphingosine, Lac-ORA, Lac-HGG and BSA Chemical modification of the antigen by periodate oxidation or borohydride reduction can effect an agar diffusion against anti-gum arabic antibodies (Se), GA=gum arabic Bl=blank.

As described by Albro and Dittmer (1968), periodate oxidation of the alkenylglycerols proceeded smoothly to completion in a buffered mixture within 3 hr at room temperature. Basing calculations on the amount of lipid phosphorus used in the hydrogenolysis experiment just discussed, 1 mol of the 1-O-alkenylglycerol will yield 1 mol of formaldehyde. As little as 0.1 iimol of alkenylglycerol can be determined. 

Very few reports have been made using this approach to synthesize anti-body-liposome conjugates. Early work (38) showed that simple acyl hydra-zides in liposomes could be used to conjugate periodate-oxidized IgM in good yield. More recently, a lipid-PEG-hydrazide derivative has been reported that was used to couple oxidized IgG to liposomes (34), albeit in low yield. Subsequent work has reported optimized conditions that resolve these problems and minimize liposome-liposome crosslinking (10). We have recently reported a variation of these procedures in which a protected thiol-hydrazide crosslinker was used to thiolate oxidized IgG and subsequently to effect coupling to maleimide derivatized liposomes (36). 

Oxidative cleavage [1, 814, before references]. Pyridine is recommended as the solvent for periodate oxidation of various vicinally disubstituted lipids. The oxidation occurs in high yield at room temperature. Thus ctj,ct,s-9.12-octadecadiene-l-aI has been obtained in 71% yield by oxidation of eu.cis-10,13-nonadecadiene-1,2-dio( with sodium metaperiodate in dry pyridine.27... 

Periodate-lysine-paraformaldehyde (PLP) - It is used to increase cross-linking of molecules in the tissue to provide better fixation. Periodate oxidizes sugars attached to lipids and proteins and generates aldehydes, which bind lysine. Paraformaldehyde then cross-links the lysine. It uses 2% paraformaldehyde,... 

By use of different extraction procedures, two types of lipopolysaccharides have been isolated from a slightly virulent strain of Yersinia pestis Some structural information was obtained from methylation and periodate oxidation studies. The immunodominant moiety of lipid A has been shown to consist of a residue of 2-amino-2-deoxy-D-glucose, A-acylated with 3-hydroxytetradecanoic acid. ° A lipopolysaccharide isolated from Y. enterolitica exhibits serological cross-reactions with lipopolysaccharides from Brucella abortus and Vibrio cholerae Common antigenic relationships between the lipopolysaccharides of Escherichia coli, Kloechera africana, and Salmonella aberdeen have been demonstrated. 

Such procedures may be suitable for the analysis of samples containing a relatively simple range of long chain bases, but some natural lipid extracts are very complex. Alternative complementary techniques must then be employed to obtain the resolution needed. The most widely used approach is to stabilise the amino group by conversion to the dinitrophenyl (DNP) derivative, for separation into different classes by TLC procedures these compounds are yellow in colour so are easily seen on a TLC plate. DNP derivatives can later be degraded to aldehydes by periodate oxidation for GC analysis in this form [464,465]. The procedure for the preparation of A/-DNP derivatives of sphingoid bases is ... 

A structurally rather bizarre lipid is the monoacetylpentol (83) isolated from Alectoria ochroleuca (305). Besides spectroscopic evidence, periodate oxidation of (83) apparently produced a mixture of 8-acetoxyoctanal (84) and 2-ethyl-2-pentylpropan-1,3-dial (85) which were isolated as the corresponding 2,4-dinitrophenylhydrazones and characterised by mass spectroscopy (305). The polyester, methyl hexa(a-hydroxyvalerate) (86) has been isolated from Cetraria nivalis and Cladonia gonecha (35). 

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