D,L-serine

Dimeric oxovanadium(IV) complexes (NBu4)[(V0)(SB)]2-nH20 have also been prepared with the SB from salicylaldehyde and L, D,L-serine and L-cysteine.791 Magnetic moments are 1.1-1.4BM, higher than for the dimeric SB derived from the L-amino acids Ala, Val, Leu, Met or Phe (0.5-0.8BM) which are probably best described as Vv complexes (114).790... 

Cyclodextrin 6-O-monophosphates in both charged and uncharged forms have also been tested for enantioselective recognition of amino acids [23]. The best results were obtained for mono-(6-0-diphenoxyphosphoryl)- 3-cyclodex-trin, giving fairly good enantioselectivity of up to 3.6 for D/L-serine in buffered (pH=7.2) aqueous solution. 

DLSERN11. D,L-Serine (neutron study) (C3H7N03). Frey MN, Lehmann MS, Koetzle TF, Hamilton WC (1973) Acta Crystallogr, Sect B 29 876 DLTYRS. D,L-iyrosine (CgHnNO. Mostad A, Romming C (1973) Acta Chem Scand 27 401 DLVALC. D,L-Valine hydrochloride (C5H12NO, Cl-). Di Blasio B, Napolitano G, Pedone C... 

Interest in phosphorus-containing calixarenes continues. Structures reported include hexa(diethoxyphosphoryloxy)calix[6]arene (8), inherently chiral 1,2-bridged calix[4]arene diphosphates, and a calixarene like C3 symmetric receptor with a phosphate function at the cavity bottom. " The purification of phosphate substituted calixarenes has been studied by chiral HPLC and by normal reverse phase HPLC. Mono(6-0-diphenoxyphosphoryl)-P-cyclodextrin (9) and mono(6-0-ethoxyhydroxyphosphoryl)-p-cyclodextrin (10) have been synthesised and show enantioselective inclusion of D and L amino acids e.g. 3.6 for D/L serine in the case of 9). ... 

Makiguchi and coworkers established a method to synthesize L-tryptophan from D,L-serine and indole by means of tryptophan synthase (E.C. 4.2.1.20) from E. coli and the amino acid racemase with low substrate specificity of Ps. striata (= Ps. putida) I65L Both D,L-serine and indole are cheaply available by chemical synthesis. Tryptophan synthase catalyzes the (3-replacement reaction of L-serine with indole to produce L-tryptophan, and the amino acid racemase with low substrate specificity converts unreacted D-serine into L-serine. Because the racemase does not act on tryptophan, almost all d,L-serine is converted into optically pure L-tryptophan. Makiguchi et al.[65] succeeded in producing L-tryptophan in a 200 L reactor using intact cells of E. coli and Ps. putida 65. Under the optimal conditions established, 110 g L 1 of L-tryptophan was formed in molar yields of 91 and 100% for added d,l-serine and indole, respectively, after 24 h of incubation with intermittent indole feeding. Continuous production of L-tryptophan was also achieved using immobilized cells of E. coli and Ps. putida. The maximum concentration of L-tryptophan formed was 5.2 g L 1 (99% molar yield for indole). 

Figure 7-5. Fragments of crystal structures of L-serine in three polymorphs (a, d) - L-serine-I at ambient pressure, (b, e) - L-serine-II at 5.4 GPa, (c, f) - L-serine-III at 8.0 GPa [127]...

The ylide 214 was prepared in several steps from D,L-serine and reacted as above to give the adduct 215 [108] (Scheme 61). This was converted into the diacid 217 the presence of the cefotaxime side-chain substantially increases the antimicrobial activity. 

Dansyl-D,L-norvaline Dansy I-D, L-asparagine Dansyl-D,L-glutamic acid Dansy I-D, L-valine Dansyl-D,L-tryptophan Dansyl-D,L-threonine Dansyl-D, L-pheny lalaninc Dansyl-D,L-methionine Dansyl-D,L-norleucine Dansyl-D,L-threonine Dansyl-D,L-serine... 

Figure 9 Thin-layer chromatogram of proteinogenic amino acid on CHIRALPLATE. Spots 1, D-alanine 2, D,L-aIanine 3, L-serine 4, D,L-serine. Application lO-iiiin streak (Linomat IV, made by Camag).

Japanese workers have described a novel microbiological synthesis of L-tyrosine and L-dopa from sodium pyruvate, ammonia and phenol or catechol respectively, using cells of Erwinia herbicola. The reaction is catalysed by tyrosine phenol lyase and is the reverse of the normal a)3-elimination reaction catalysed by this enzyme. The L-tyrosine or L-dopa synthesised by this enzymatic method precipitates from the reaction media during incubation. The maximum amount of L-tyrosine synthesised by this method was 60.5 g per litre and of L-dopa 58.5 g per litre. The process is a variation on the analogous procedure reported by the same school which used d L-serine in place of sodium pyruvate. 

Figure 6 Remission-location curves (a) dansyl-D,L-glutamic acid (b) dansyl-D.L-serine (c) D,L-aspartic...

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