A variety of furan-modified nucleoside phosphoramidite monomers has been prepared and efficiently incorporated into oligonucleotides. These take part in Diels-Alder reactions with fluorescent maleimides to give fluorescent-labeled oligonucleotides. This represents a strategy for oligonucleotide labeling that is orthogonal to amine-based methods.

A novel photocleavable universal support for the automated solid phase synthesis of oligonucleotides is described. The linker between the growing oligonucleotide chain and CPG support contains a nucleophilic amine protected with a photocleavable group. On exposure to UV light, this group is detached and the free amine affords cleavage of the oligonucleotide from the support. The use of long wavelength UV light avoids damage to the DNA.

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Enzyme catalysis by a cell free preparation from Lactobacillus leichmannii is used to accomplish the transformation of thymidine to deoxynebularine in the presence of purine. The resulting mixture of nucleosides is then converted to their 5'-dimethoxytrityl derivatives which are easily separated using conventional chromatography. Phosphitylation of the 5'-dimethoxytrityl-deoxynebularine then gives the phosphoramidite derivative suitable for incorporation into oligonucleotides.

Incorporation of [2-13C]-, [3-13C]-, (4R)-[5-13C]- and (4S)-[5-13C]-leucines into paniculide by tissue cultures of Andrographis paniculata shows that (a)(3S)-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) from leucine breakdown is not incorporated direct into mevalonic acid (MVA) but that (b) both the acetyl-CoA and acetoacetate produced by leucine breakdown via HMG-CoA are subsequently incorporated into HMG-CoA and MVA.

Experiments with intact callus cultures of Andrographispaniculata and a derived cell-free system have established that: (1) the biosynthesised γ-bisabolene has the Z-configuration 6; (2) the biosynthetic intermediate is a 6-trans-13 and not a 6-cis-15 farnesyl pyrophosphate; (3) in paniculide B 17, and probably also in γ-bisabolene 14, the ring carbon derived from C-2 of mevalonate is anti to the side chain; (4) mevalonolactone and trans,trans-famesyl pyrophosphate are incorporated into γ-bisabolene without hydrogen loss respectively from C-5 and C-1; cyclisation to the bisabolenyl cation therefore does not involve prior trans to cis isomerisation of the terminal double bond of farnesol by a redox mechanism; (5) taken together with our previous findings, it is established that Andrographis cultures contain two independently functioning enzymes: (i) a trans,trans- to cis,trans-farnesol isomerase, and (ii) a trans,trans-farnesyl pyrophosphate isomerase-cyclase. The absolute configuration of paniculide B has been established by an X-ray cristallographic analysis of its bis-p-bromobenzoate.

Incorporation of [3-13C]-leucines into paniculides by tissue cultures of Andrographis paniculata shows that (a)(3S)-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) from leucine breakdown is not incorporated intact into paniculide and (b) leucine is incorporated by breakdown to acetyl-CoA and its subsequent incorporation via HMG-CoA and MVA.

Proteolipid apoproteins have been isolated from a whole bovine brain homogenate by chloroform/methanol extraction, and fractionated by chromatography on modified (lipophilic) Sephadex, followed by ion-exchange chromatography on CM-Trisacryl. The various final, highly hydrophobic, fractions are homogeneous (sodium dodecyl sulfate/polyacrylamide gel electrophoresis). Transmembrane ion transfers were studied by 22Na + flux and electrical conductance measurements. Single channel events were observed at low protein concentrations, in particular with one of the final homogeneous apoproteolipids of molecular mass 24 kDa.

I. Freer, G. Pedrocchi-Fantoni, D. J. Picken and K. H. Overton, J. Chem. Soc., Chem. Commun., 1981, 80 DOI: 10.1039/C39810000080

A cell-free system from Andrographis paniculata tissue cultures catalysed the transesterification of administered cis, trans-farnesol-[1-3H2] with (glyceryl) oleate and palmitate present in the coconut water that forms part of the culture medium.

The notion of culturing plant cells in vitro goes back to the beginning of this century. However, successful experiments in the culturing of unorganized plant cells for prolonged periods were first reported in 1939 independently by GAUTHERET (40) and WHITE (112), who in essence established the technique still in use today.

Experiments with intact callus cultures of Andrographis paniculata and a derived cell-free system indicated that (a) the biosynthesised γ-bisabolene has the Z-configuration (3); (b) the biosynthetic intermediate is 2-cis, 6-trans-(1)- and not 2-cis,6-cis-(2)-farnesol pyrophosphate; (c) in paniculide B (5) the ring carbon derived from C-2 of mevalonate is anti to the side chain.