Threonine dansylation

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... 

Spontaneous hydrolysis of amphomycin in water solution over about two months was observed at room temperature, probably because of the acidity provided by the free carboxyl groups. A decapeptide (37) and N-acylaspartic acid were thus obtained. Treatment of the decapeptide with nitrous acid destroyed the methylaspartic acid residue and transformed DABc threonine. Dansylation showed that methylaspartic acid was the only N-terminal amino acid the fact that no derivative was obtained from pipecolic acid or DAB, supported the presence of a diketopiper-azine. The possibility that the diketopiperazine could have been formed under mild conditions of degradation was ruled out by experiments... 

Fig. S6. Separation of D,L-dansyl amino acids. Conditions 0.65 oiAf L 2>isopropyl-dien-Zn(II) 0.17 A NH,Ac to pH 9.0 with aqueous NI 35/65 CH,CN/H,0 T - 30 flowrate 2 tnl/min column 15 cm by 4.6 mm i.d. S iun Hypersil C solutes CySO H -cysteic acid Ser - serine Trp - tryptophan thr - threonine Norval - norvaline Leu w leucine Norleu - norleucine Phe phenylalanine. Detection at 254 nm. Reprinted with permission from LePage ef at. C246), Am/. Chem. Copyright 1979 by the American Chemical Society.

Biochemical Amino acids As dansyl amino acids Asparagine Glutamate Dansyl hydroxide Serine Threonine Alanine ... 

CD9 Dansyl-methione, dansyl-phenylalanine, dansyl-alanine, dansyl-leucine, dansyl-norvaline, dansyl-tryptophan, dansyl-glutamic acid, dansyl-aspartic acid, dansyl-threonine, l,l -binaphthyl-2,2 -diylhydrogenphosphate, carvedUol, erythro-mefloquine, clidinum bromide, FMOC-phenylalanine, FMOC-tryptophane, FMOC-alanine, narigin, hespesperetin, neohesperidin, neoeriocitrin 29... 

Ding et al. described the chiral separation of enantiomers of several dansyl-amino acids by HPLC in the reversed-phase mode. The natural logarithms of selectivity factors (In a) of all the investigated compounds depended linearly upon the reciprocal of temperature (1/T). For most processes of enantioseparation, enantioselectivity, a, decreased with increasing of temperature, and the processes of chiral recognition were enthalpy-controlled. It is very interesting that enantioselectivity, a, increased with increasing temperature for dansyl-threonine (Dns-Thr) at a... 

As shown in Table 5.1, ARf values of the optical antipodes were included between 0.02 (dansyl-DL-threonine, Thr, and dansyl-DL-valine, Val) and 0.06 (dansyl-DL-aspartic acid, Asp) however, a good resolution of the enantiomers was observed owing to the compactness of the spots. The L-enantiomer was always more retained than the D-enantiomer. This technique allowed the determination of little amounts of Dns-o-enantiomer in the L-form (i.e., it was possible to quantify impurities of Dns-o-glutamic acid in the L-enantiomer as low as 1%). 

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