D-Histidine

D-Histidine, systematic name, formula, and molecular weight, 2 557t DL-Histidine, systematic name, formula, and molecular weight, 2 558t L-Histidine... 

A possible explanation for the preference of living systems for the L (levorotatory) over the D (dextrorotatory) optical isomer may be associated with the stereoselective properties of layered minerals. To test this hypothesis, the rates of L- and D-histidine intercalation into HT layered compound was investigated using the pressure-jump relaxation technique (21). The rate constants and interlayer spacing based on this investigation are summarized in Table V. As shown the slightly enhanced rate for L-histidine suggests that relative chemical reactivity may be associated with natural selection of the L-form of amino acids in nature. 

Soupart, P., Contribution 4 l etude de l histidinurie au cours de la grossesse. Le debit urinaire d histidine au cours du cycle menstruel normal. Acta Clin. Belg. 9, 297-318, 319-324 (1954). 

Ikeda, T., Amoh, H. and Yasunaga, T. (1984). Stereoselective exchange kinetics of L-histidine and D-histidine for Cl- in the interlayer of a hydrotalcite-like compound by the chemical relaxation method. J. Am. Chem. Soc. 106, 5772. 

C11H15N03 2-hydroxy-2-phenyl butyl carbamate 50-19-1 25.00 1.1220 2 22543 C11H17N304 Na-boc-D-histidine 50654-94-9 25.00 1.2178 2... 

Fig. 9 CD spectra for the host Cu(II)-D-histidine spectrum and the mixed complexes with a series of tripeptides.

Fig. 10 CD spectra for (a) the Cu(II)-D-histidine host complex and for the mixed ligand complexes with (b) bovine insulin, (c) human insulin, (d) porcine insulin, and (e) human LysPro insulin.

In other tests of the ligand exchange/CD detection assay procedure, it was demonstrated that 51 of a total of 53 di- and tripeptides could be uniquely identified by the character of the changes in the CD spectra for the mixed Cu(II)-peptide-D-histidine complexes. A series of 19 neuropeptides was the focus of another... 

Properties Colorless crystals. DL-histidine, mp 285-286C with decomposition D(+)-histidine, mp 287-288C l(—)-histidine, mp 277C with decomposition. Soluble in water insoluble in alcohol and ether. Shows optical activity. Available commercially as L(+)-histidine hydrochloride and as the free base. 

An enantioselective oxidation of 3,4-dihydroxy-L-phenylalanine catalyzed by an W-lauxoyl-L- or -D-histidine-Cu(II) complex in the presence of cetyltrimethyl-ammonium bromide as cosurfactant was described by Yamada et al. [54]. 

The separation techniques described in Section 9.1.2.1 allow rapid parallel processing of synthetic reactions, a critical requirement for the synthesis of combinatorial libraries that may contain hundreds, thousands, or even millions of members. Several synthetic formats are discussed below, using two examples. First, we will consider a library of all the possible tetrapeptides formed using any of the four amino acids aspartate (D), histidine (H), lysine (K), and threonine (T). There are 4x4x4x4 = 44 = 256 combinations. Second, we will consider a library of all the possible tetrapeptides formed using any of the 20 natural amino acids. There are 160 000 combinations as indicated above. 

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