A new bacterial sphingophospholipid containing 3-aminopropane-1,2-diol

1. A new sphingophospholipid has been isolated from the bacterial fraction of sheep rumen contents. 2. This new lipid has been characterized as a ceramide phosphate moiety esterified to 3-aminopropane-1,2-diol through the primary alcohol group. 3. Mass spectrometry has shown the intact lipid to contain a vicinal hydroxyl amino grouping, and oxidation with periodate converts it quantitatively into a new phospholipid which is probably ceramide phosphorylglycolaldehyde. 4. The sphingophospholipid contains a mixture of saturated long-chain bases mainly with branched-chain alkyl groups, which are typical of a microbial origin. 5. A Gram-negative bacterium isolated from rumen contents contains about 30% of the new lipid in its phospholipids when grown in pure culture.     

Debenzylation and detritylation by bromodimethylborane: synthesis of mono-acid or mixed-acid 1,2- or 2,3-diacyl-sn-glycerols.

A novel method of deprotecting primary alcohols protected with either benzyl or trityl groups by using bromodimethylborane under mild reaction conditions (dichloromethane, -20 to 5 degrees C) has been applied to the synthesis of optically pure mono-acid or mixed-acid 1,2- or 2,3-diacyl-sn-glycerols. This method was particularly useful for the synthesis of long saturated acyl (C12 to C24) as well as unsaturated diacyl-sn-glycerols since little or no acyl migration occurred during deprotection. Diacylation of 3-benzyl-sn-glycerol or 1-benzyl-sn-glycerol followed by bromodimethylborane debenzylation gave mono-acid 1,2- or 2,3-diacyl-sn-glycerols, respectively. The mixed-acid 1,2- or 2,3-diacyl-sn-glycerols were prepared from 1-acyl-sn-glycerols or 3-acyl-sn-glycerols, respectively, by tritylation, acylation with a different fatty acid, followed by detritylation with bromodimethylborane.     

A new method for the 3′-deoxygenation of butirosins A and B

An aziridine ring-formation involving the reaction of adjacent amino and alcohol groups with triphenylphosphine, carbon tetrachloride, and triethylamine was applied at the 2′ and 3′ positions of butirosin A (1a) and B (1b). The amino groups at the 2′ position of 1a and 1b were p-methoxybenzylated to increase the nucleophilicity of the nitrogen atom and to avoid the formation of a P-N linkage, and the N-p-methoxybenzyl derivatives were converted into the aziridine derivatives, which were then subjected to hydrogenolysis and removal of the protecting groups to give 3′-deoxybutirosin A (7a) and B (7b), respectively. This new method is compared with the conventional N, O-protecting method that involves several complex steps.     

A new method for the synthesis of N3-alkylated analogs of 5-fluorouracil.

5-Fluorouracil (5-FU) is converted to the adducts 1a,b then subjected to Mitsunobu reaction with the secondary alcohols to give the condensates 2a,b. Hydrogenation of 2a,b with Pd/C affords N3-alkyl-5-fluorouracil 3a,b.     

A new method for determining the Michaelis constant

A new method is described for evaluating the parameters K(m) and V in the Michaelis-Menten equation, and is illustrated with experimental data from the literature.     

A new method for the preparation of solid-phase immunoadsorbents

A solid-phase immunoadsorbent was prepared by insolubilization of antibody during precipitation with Na₂SO₄. The polyaldehyde macromolecule created by periodate oxidation of dextran (macrofixative) served as the insolubilizing, crosslinking agent. After appropriate fixation, the precipitate was stable to removal of the precipitating salt, to washing, and, to a large extent, to heating in the denaturing detergent, sodium dodecyl sulfate. Under proper conditions, the precipitate retained satisfactory antibody activity, although very high molecular weight antigens were apparently excluded from the internal active sites of the solid-phase matrix. This method provides the advantage of insolubilization of the primary antibody in a small volume; for analytical work, the entire precipitate, with bound antigen, may be quantitatively applied to a polyacrylamide gel (tube or slab) and electrophoresed without overloading by the binding antibody. This method might also be extended for use in immunoisolation procedures employing standard eluting agents, as well as insolubilization of proteins other than immunoglobulin.     

A new method for multi-site-directed mutagenesis

A modified method for multi-site-directed mutagenesis was developed here based on polymerase chain reaction (PCR), DpnI digestion, and overlap extension. It needs only methylated plasmids obtained by Dam methyltransferase or plasmids from dam⁺Escherichia coli containing target gene. The procedure consists of PCR, DpnI digestion, overlap extension PCR, and plasmid transformation. The method was developed for multi-site-directed mutagenesis, including close proximity of mutation sites. It does not require 5′-phosphorylated primers and ligation and, thus, significantly simplifies the routine work and reduces the experimental cost for multi-site-directed mutagenesis.     

A new colorimetric method for the estimation of resorcinol

A new, rapid, simple, and sensitive colorimetric method for the estimation of resorcinol in microgram amounts is described.     

A new method for the identification of dinoflagellate cysts

When examined under crossed nichols on a polarizing microscopedinoflagellate cysts exhibit a characteristic cross-like interferencefigure which highlights cysts from background particulates.Thisdinoflagellate ‘fingerprint’ provides an importantnew tool for the analysis of the occurrence of cysts in detritusand sediment.