Acetate, active from lysine

Chemical conversions of marcfortine to paraherquamides have been achieved [415]. Utilising various soil-derived microorganisms, individual hydroxylation at carbon atoms 5, 10, 12, 14, 15, 16 and 27 has been realized [416] but no improvement on the activity of (244) was observed. A study of the biosynthesis of (244) has shown that it is derived from methionine, tryptophan, lysine and two isoprene units, the latter two being derived from acetic acid. The pipecolic acid moiety arises from lysine via a-ketoglutarate [417]. 

Piperidine Alkaloids.—The hypothesis that dioscorine (112) was derived from six acetate units has been tested by administration of sodium [l- " C]acetate to Dioscorea hispida. Degradation of the dioscorine isolated showed, significantly, that of the carbons of the isoquinuclidine ring only C-5 was heavily labelled (30% of total). The remaining activity was located equally at C-10 and C-12. Thus dioscorine is built of only four acetate units, the remaining carbons of the skeleton being derived probably from lysine via a piperidine moiety such as A -piperideine (Scheme 10). 

Fig. 7. Ionic-hydrophobic interaction chromatography of tRNA. Column trioctyhnethylanomonium chloride-treated ODS-Hypersil (4.6 x 250 mm) sample 2 mg of bulk tRNA from baker s yeast, showing amino acceptor activity above background for valine (Val), isoleucine (lie), arginine (Atg), lysine (Lys), serine (Ser), phenylalanine (Phe) and tyrosine (Tyr) chromatographic conditions 100% buffer A (0.5 M ammonium acetate, pH 5.0) to 60% A, 40% buffer B (5 M ammonium acetate, pH 5.5) in 1080 min 0.5 ml/min 35 °C. The continuous line r resoits the absorbance at 260 nm the broken lines the amino acid acceptor activities. From [28].

While for developing of simple piperidine alkaloids, e.g., pelletierine (Punica granatum), piperine (Piper nigrum et longum), and lobeline (Lobelia inflata), only one molecule of lysine is necessary, for quinolizidine alkaloids - e.g., lupinine (Lupinus luteus), sparteine of antiarrhythmic activity (Sarothamnus scoparius), and cytisine of respiratory stimulant effect (Laburnum species) - two molecules of lysines are indispensable. It was also proved that lycopodine (Lycopodium tristachyum, clubmoss) of quinolizidine structure has no polyketide origin, but it is a modified dimer of pelletierine, which, in turn, is derivable from lysine and acetate. 

Alterations in pH also can be responsible for the increase in solubility of loaded active agents. Glucose oxidase immobilized on sepharose beads were incorporated into ethyl vinyl acetate matrices along with insulin in the solid form. Glucose from blood enters these matrices, gets oxidized to glucuronic acid, and the decrease in pH increases the solubility of insulin, which diffuses out. The insulin in this case was modified by the addition of three extra lysine residues that ensured an isoelectric point of pH 7.4 for the molecule.33... 

If one accepts the view that the serum seromucoids are soluble in 0.64N perchloric acid as described by Winzler, our studies of the isolated perfused liver utilizing lysine and acetate clearly indicate that the serum seromucoids are virtually exclusively synthesized by the liver. The fact that the seromucoid fractions obtained from eviscerated surviving rats, particularly those bearing an experimental tumor, contain no significant carbon-14 activity after a dose of lysine-C14 is in keeping with this view. The detailed data of the electrophoretic separations from our experiments with lysine-C14 and sulfur-3 5-labeled sulfate in the seromucoid fractions are interpretable in terms of these fractions... 

Figure 9.64 Chromatogram obtained after injection of a yQ-galactosidase incubation mixture onto a 45 mm x 3.6 mm cation-exchange column. Mobile phase pyridine-acetic acid-water (6 60 176, v/v). Flow rate, 0.4 mL/min temperature, 50°C. In front of lactose-lysine some free amino acids elute which are the result of proteolytic activity in the intestinal enzyme preparation. Peaks 1, lactose-lysine 2, /8-alanine (internal standard) 3, fructose-lysine. (From Schreuder and Welling, 1983.)...

The alkaloid (93) which is produced by Haloxylon salicornicum shows a structural resemblance to pelletierine (89). A feeding experiment58 with [6-14C]-lysine in intact plants has supported the related biosynthesis in Scheme 18. Activity was incorporated at C(6) of the alkaloid as shown. Surprisingly, no activity was incorporated from [2-14C]acetate but this negative result could be due to the failure of acetate to reach the site of synthesis. 

The initial step in the microbiological metabolism of lysine to acetate, butyrate, and ammonia is the reversible interconversion of L-lysine and L-jS-lysine via exchange of the a-amino group and a /8-proton catalyzed by lysine 2,3-aminomutase (Scheme 49). The reaction has been observed in several species of Clostridium, Nocardia, and Streptomyces (218, 219), but the mechanistic studies have concentrated on the enzyme from Clostridium subterminale SB4, which has been purified and characterized (220). The enzyme is extremely sensitive to reversible oxygen inactivation, with reactivation achieved by anaerobic incubation with a thiol and Fe(II), and a protein-bound Fe(II) is apparently required for activity (220). The exchange reaction is also accelerated by S-... 

C the acetic acid contained 47% of the activity of the lycopodine, and from the experiment with acetate-2- C the acetic acid contained 21% of the activity of lycopodine. These data are in harmony with the pelletierine but not with the polyketide hypothesis. When it was found (see below) that two molecules of lysine were specifically incorporated into lycopodine (65, 66) the polyketide hypothesis could be dismissed. 

Lysine is converted into carnitine through a chain reaction driven at two points by dioxygenases (or hydroxylases) that act on y-butyrobe-taine and trimethyl-lysine and that require vitamin C for full activity. Carnitine is essential for the transport of energy-rich fatty acids from the cytoplasm to the mitochondrial matrix where they are catabolised by jS-oxidation to acetate. 

Three histone-specific acetyltransferases have been partially purified and characterized from rat thymus nuclei (225). The enzymes were extracted from rat thymus nuclei by sonication in the presence of 1M ammonium sulfate and separated into two active fractions (A and B) by DEAE-cellulose chromatography. Fraction B was further separated into two active fractions (Bi and B2) by gel filtration on Sephadex G-200. Each fraction was then purified further by chromatography on hydroxyapatite. The molecular weights, determined by Sephadex G-200 and by sucrose density gradient centrifugation, were 99,000, 110,000, and 92,000 for enzymes A, Bi, and B2, respectively. All three enzymes required acetyl CoA as acetate donor, and the activity of the enzymes was inhibited by p-chloromercuribenzoate. Acetyltransferase A preferentially acetylated histone I (FI) and also poly-L-lysine. Acetyltransferase Bi and B2 preferred histone H4 (other names IV, F2al) and did not acet-ylate poly-L-lysine and histone H3 (III, F3). In addition to c-N-acetyl-lysine, two other unidentified amino acid derivatives were obtained from a digest of histone H4 acetylated by the two B enzymes. 

Uniformly labeled L-lysine- " C administered to hemlock plants afforded radioactive coniine, but no degradative studies were produced by these authors to prove that labeling was present in the piperidine ring. Instead, feeding sodium acetate-to 2-year-old C. maculatum plants indicated that alkaloids obtained from the plant (coniine, y-coniceine, and conhydrine) presented labeling. Chemical degradation of the obtained coniine showed that activity was mostly and evenly distributed in even-numbered C-atoms, which allowed to speculate that hemlock alkaloids are derived from an 8-C aliphatic polyketo chain produced by the linear attachment of four acetate units probably through the condensation of 4 molecules of acetyl-CoA. The results of may be due to metabolization of lysine- C to radioactive acetate units, then incorporated to coniine. 

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