Effect of Monofluoroacetate on Pyruvate-3-14C and Glucose-U-14C Incorporation into Ipomeamarone

The olfactory system has a remarkable ability to detect and discriminate a vast variety of odorant molecules. In mammals, hundreds to thousands of odorant receptors (ORs) expressed in olfactory sensory neurons play an essential role in this discrimination. Odorants are recognized by ORs in a combinatorial fashion in which a single odorant activates a particular combination of receptors, leading to its perception as a particular aroma. It is well known that enantiomers emit different aromas in spite of exhibiting otherwise identical chemical properties. To elucidate the molecular basis for the difference, we recorded responses to l- and d-menthol in the mouse olfactory bulb and found that enantiomers elicited similar but overlapping and distinct receptor activation patterns. We then identified l-menthol-specific and d-menthol-biased receptors and performed detailed structure–activity relationship studies, revealing high stereoselectivity of the enantiospecific menthol receptor. The binding site on ORs appears to have evolved to distinguish subtle differences in very similar odorant structures.     

Synthesis of eicosa-2-trans-8,11,14-all cis-tetraenoic acid-3-14C and DL-3-hydroxy eicosa-8,11,14-all cis-trienoic acid-3-14C

A general procedure for the synthesis of 2-trans polyenoic fatty acids and of dl-3-hydroxypolyenoic acids is described. The 2-trans acids are prepared by LiAlH(4) reduction of a suitable polyenoic fatty acid ester to the alcohol, formation of the tosylate, oxidation to the aldehyde, and Doebner condensation of the latter with malonic acid. The 3-hydroxy acids are obtained by reaction of the acyl chloride of a suitable polyenoic acid with the sodium enolate of methyl acetoacetate and sodium methoxide to give the 3-keto ester, the keto group of which is reduced with sodium borohydride to the alcohol. These procedures were applied to the synthesis of eicosa-2-trans-8, 11, 14-all cis-tetraenoic acid-3-(14)C and DL-3-hydroxy eicosa-8, 11, 14-trienoic acid-3-(14)C.     

Post-translationally modified 14-3-3 isoforms and inhibition of protein kinase C

This report compares the ability of individual members of the 14-3-3 protein family to inhibit particular protein kinase C (PKC) isoforms. We also show that two of these 14-3-3 isoforms ( and ) specific to mammalian and avian brain arein vivo post-translationally modified forms of and respectively. The presence of this modification enhances the activity of 14-3-3 as an inhibitor of protein kinase C nearly two fold.A method for analysing isoforms of 14-3-3 on acid-urea gels is also described. This permits the complete separation of all major isoforms and their unequivocal identification by a range of isoform specific antisera. The activity of recombinant 14-3-3 and isoforms renatured by a novel method after separation by reverse phase HPLC are compared. The effects of diacylglycerol and the phorbol ester, PMA (phorbol 12-myristate 13 acetate) on the inhibition suggest that one of the sites of interaction of 14-3-3 may be the cysteine-rich (C1) domain in PKC.     

Preparation of L-tyrosine-ring- 14 C, L-DOPA-ring- 14 C and related metabolites

The reversibility of the tyrosine phenol-lyase reaction has been utilized to develop a simple system in which phenol-¹⁴C is incorporated into l-tyrosine in high yield. By use of mushroom tyrosinase, catechol-¹⁴C can be prepared from phenol-¹⁴C and l-DOPA-¹⁴C from l-tyrosine-¹⁴C. Catechol-¹⁴C can also be incorporated into l-DOPA-¹⁴C by use of tyrosine phenol-lyase, giving the possibility of preparing DOPA with two labeling patterns in the ring when starting with phenol-¹⁴C. Two further tyrosine metabolites, para-coumaric acid and homogentisic acid, have also been enzymatically prepared with ¹⁴C in the ring.     

Incorporation of 3H and 14C from (6 alpha-3H)penicillin N and (10-14C,6 alpha-3H) penicillin N into deacetoxycephalosporin C.

1. In a cell-free system prepared by lysis of protoplasts of Cephalosporium acremonium mutant M-0198, 3H and 14C were incorporated from singly- and doubly-labelled penicillin N into deacetoxycephalosporin C. 2. The deacetoxcephalosporin C obtained from the above feeding experiments was converted into two different crystalline derivatives, namely N-phthalimidodeacetoxycephalosporin C bisbenzhydryl ester and N-phthalimidodeacetoxycephalosporin C bisdicyclohexylamine salt and recrystallized to constant specific activity or constant ratio of specific activity. 3. That 3H is incorporated at C-7 in the biosynthesized deacetoxycephalosporin C was shown by the loss of radioactivity (95.2%) after methoxylating the derived N-phthalimidodeacetoxycephalosporin C bisbenzyhydryl ester. 4. Deacetoxycephalosporin C was also the product of the cell-free reaction conducted in the presence of ferrous ions and ascorbic acid, as shown by two-dimensional paper electrophoresis-chromatography; these additives appreciably improved the efficiency of conversion.