Histidine derivatives

The 3-methylhistidine is easily distinguished from the 1-methyl derivative (formed by alkylation, 3.4) by electrophoresis at pH 6.5 (Johnson et al. 1967) as well as with automatic analyzers (Spackman et al. 1958 Johnson et al. 1967 Elzinga 1970). In general a longer short column (0.9 x 15 cm or 0.9 x 20 cm) is required for good separations of 3-methylhistidine from histidine (the 3-methyl derivative elutes between histidine and NH3 in these systems). The color value of 3-methylhistidine is 85% that of histidine (Spackman et al. 1958). 

Several electrophoretic and chromatographic systems have also 

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Generally speaking imidazole is the nucleophilic functional group, and many of the chiral surfactants are histidine derivatives (Brown and Bunton, 1974 Brown et al., 1981). In other cases mixed systems have been used, e.g. an inert cationic surfactant plus a chiral amphiphilic histidine or hydroxa-... 

Deacylation of p-nitrophenyl derivatives of amino acids Chiral histidine-derived surfactants + CTABr. Rates and enantioselectivities examined Matsumoto and Ueoka, 1983... 

HC Beyerman, J Hirt, P Kranenburg, JLM Syrier, A van Zon. Excess mixed anhydride peptide synthesis with histidine derivatives. Rec Trav Chim Pays-Bas 93, 256, 1974. 

Use of histidine derivatives substituted at the x-nitrogen. -protection prevents isomerization during coupling (see Section 4.3), but -protection may not suppress it completely (see Section 6.10). 

K Barlos, O Chatzi, D Gatos, G Stavropoulos, T Tsegenidis. Fmoc-His(Mmt)-OH and Fmoc-His(Mtt)-OH. Two new histidine derivatives N""-protected with highly acid-sensitive groups. Preparation, properties and use in peptide synthesis, (dimeth-ylsilyldichloride) Tetrahedron Lett 32, 475, 1991. 

Scheme 22 Ishihara s histidine derivative catalyzed KR of mono-protected cis-diols [234]...

L-histidine-derived Cactaceae Dolichothele sphaerica Dolichotheline... 

L-aspartic acid L-cysteine L-glutamine L-glutamic acid L-glycine L-histidine Histidine-derived alkaloids True alkaloids... 

Isoguanine (94), which is found in Prioneris wings along with hypoxanthine (92), xanthine (91), and uric acid (95), shows antineoplastic activities (Table VI) (57). Isolation of urocanic acid (137) from this wing material represents the first detection of this histidine derivative in an arthropod (Table VIII). A nonpteridine pigment, xanthommatin (58) (cf. Section II,B,l,b), is found in the larval body of Pieris brassicae (Table V). 

The histidine derivatives, l-methyl-5-thiolhistidine (639) and its disulfide (640) were isolated from unfertilised eggs of the sea urchin Paracentrotus lividus [507] and from those of other echinoderms [508]. Their structures were revised after an unambiguous synthesis [509]. L-Ovothiol A disulfide (640) was also shown to be the egg release pheromone of the marine polychaete worm Platynereis dumerilii [510]. 

Eyem and Sjoquist have suggested the use of short (4.5 m) glass capillary columns and reported the separation of 19 of 20 silylated methyl thiohydantoin (MTH) derivatives of the amino acids (62). The histidine derivative can be separated on the same column by starting at a higher temperature. Separation of some of the silylated PTH derivatives was also demonstrated, though not in as much detail as the MTH derivatives. 

Glycosidic coupling of the acceptor 27 and the donor 23 cleanly provides disaccharide 28, in which the diphenylphosphate activation is clearly preferable to earlier methods. The a-linkage is retained exclusively due to the presence of the C2 acetate, as planned. Activation and coupling of disaccharide 28 with the protected (3-hydroxy-l-histidine derivative 29 gives the expected adduct, with an a/ 3 anomer ratio of at least 13 1. This is probably due to the low reactivity of the glycosyl acceptor, which favors formation of the more stable a-anomer. The adduct is then converted into 30, which is suitably prepared for linking with tetrapeptide S and pyrimidoblamic acid. 

H NMR Chemical and Coordination-Induced Shifts for the Two Protons of the Imidazole Ring in Aqueous Oxobisperoxovanadate Histidine-Derived Complexes of VOL2X Stoichiometry... 

H-bond interactions between the catalyst and substrate were suggested by Campbell to explain why his N-(4/-pyridinyl)-a-methylproline-derived catalysts 16 and 17 (Fig. 8.4) are more enantioselective for N-acylated 1,2-amino alcohols (s = 9-18.8) than for other classes of substrate [95-98]. Recently, Ishihara has designed the histidine derivative 34 as a minimal artificial acylase for the KR of mono-protected cis- 1,2-diols and N-acylated 1,2-amino alcohols [135]. This catalyst incorporates a sulfonamide linkage specifically to allow the NH group to engage as a H-bond donor with the substrates, and gives impressive levels of selectivity with a range of appropriate substrates (Scheme 8.16). 

Regioselectively fluorinated heteroaromatic compounds can be obtained on transformation of amino groups using the classical Balz-Schiemann reaction (65MI1 71JA3060) or modified routes. When a solution of suitably protected 2-amino- and 4-amino-DL-histidines in 50% fluoroboric acid are treated with sodium nitrite and subsequently photolyzed, the 2-fluoro- and 4-fluoro-DL-histidine derivatives are obtained (73JA4619, 73JA8389) (Scheme 7). 

Polylysine-g-histidine derivatives, (1), prepared by Pack [1] were effective as biocompatible endosomolytic delivery agents. 

Disadvantage The chiral centre of this histidine derived carbene precursor is in the backbone and thus too far removed from the carbene carbon atom to influence the outcome of a catalytic reaction. 

Protection of imidazole NH, The imidazole NH group of the histidine derivative 2 is protected as the p-methoxysulfonamide 3 by reaction with 1 and EtsN. This sulfonamide derivative is stable to the acidic conditions required to remove the... 

X-Ray crystallography has been employed to demonstrate that, in the solid state, histamine is 5-(2-aminoethyl)imidazole, a result which contrasts with the structure determined for its cation. However, from determinations of pXa values of histamine and its two possible methyl derivatives, a Kt value of 4 (4- 5-substituted isomer) has been found. In fact, in aqueous solution histamine exists largely as the protonated form (31) which reverts to (32) on neutralization. Electron-withdrawing groups in the imidazole ring of histamine cause the 4-isomer to predominate, but methyl groups have little effect (80AHC(27)24l). The 4-substituted zwitterionic form for histidine is preferred in basic medium this form is maintained in a number of histidine derivatives (e.g. the polypeptide bacitracin). 

It is understandable that in the early days the x/rr distinction was neglected, because no general method of distinguishing between isomeric N - and N -substituted structures in histidine derivatives was available. It is still the case that this distinction is nontrivial, but the problem has been solved in specific cases by crystallography, chemical degradation, or nuclear Overhauser effect measurements, and no exception to the cross-ring coupling constant criterion of Matthews and Rapoport ° is known. 

N" -Protecting groups are covered below in individual subsections (see Table 1 for a summary of some key N -protected histidine derivatives). 

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