Poly-L-histidine

Lee ES, Shin HJ, Na K et al (2003) Poly(L-histidine)-PEG block copolymer micelles and pH-induced destabilization. J Control Release 90 363-374... 

L-ascorbic acid Amperometric Enzyme-less biosensor using poly-L-histidine-copper complex as an alternative biocatalyst Hasebe et al. (1998)... 

The metalloporphyrin complexes and their derivatives have been studied from the standpoint of model compounds of hemoglobin. The polymer-metalloporphyrin complexes are also formed by the reaction in Scheme 8, and a few qualitative investigations have been made with poly(L-lysine)9,10, poly(L-histidine)11, and poly(vinylimidazole)12 as the polymer ligand. Blauer9 has studied the complex formation of heme with poly(L-lysine) and has discussed the effects of the molecular weight and secondary structure of poly(L-lysine) on complex formation. 

Shibata et al.u have reported on the heme complexes of poly(L-histidine) and the copolymer of L-histidine and L-glutamic acid. Poly(L-histidine) and the copolymer formed the six-coordinate and five-coordinate heme complex, respectively. Hatano12 found that the formation constant of the complex of heme with poly(N-vinyl-2-methylimidazole) 3 was larger by a factor of 102 or 103 than that of the corresponding monomeric heme complex. 

Weitere Untersuchungen befaBten sich mit den optischen Eigenschaften von Poly-l-benzyl-L-histidin und Poly-L-histidin (175) sowie der basenkatalysierten Bildvuig von cyclischen Verbindungen aus Poly-L-asparaginsaure- 8-benzylester und Poly-L-glutamin-y-benzylester (173). 

Benns, J.M., Choi, J.S., Mahato, R.I., Park, J.S. and Kim, S.W. (2000) pH-sensitive cationic polymer gene delivery vehicle V-Ac-poly(l- histidine)-graft-poly(l- lysine) comb shaped polymer. Bioconjug. Chem., 11, 637-645. 

The work presented in the next section concerns the immobilization of retinoic acid by three polyamino acids poly(-L-lysine), poly(-L-arginine) and poly(-L-histidine). The mesomorphous structure of these complexes, which are prepared as nano-particles, has been examined. Then we will report on the physicochemical characteristics of water-soluble complexes formed between PEO-PLL block copolymers and retinoic acid. The structure in the solid-state and solution are discussed. Further the dissociation of the complex when changing the pH is reported. Finally, the immobilization of retinoic acid by PEI with different molecular weights is presented. 

Fig. 12 Substances used for complex formation and nanoparticles, (retinoic acid) All-trans retinoic acid, (PLA) poly(-L-arginine), (PLH) poly(-L-histidine), (PLL) poly(-L-ly-sine). As dispersing agent a tri-block copolymer was used. It consisted of ethylene oxide and propylene oxide (Poloxamer 188). Reprinted with permission from [142]. Copyright 2000 American Chemical Society...

Fig. 14 Wide-angle X-ray diagrams of crystalline all-trans retinoic acid (curve a) and its complexes with polyamino acids. In the curve of poly(L-arginine) retinoate and poly(L-lysine) retinoate (curves b and d, respectively) no crystalline reflections were found. However, three weak crystalline reflections are present in the curve of poly(L-histidine) retinoate at s=1.69, 2.48 and 2.73 nm-1 (curve c). This is indicative of a partially crystalline complex structure. Reprinted with permission from [142]. Copyright 2000 American Chemical Society...

In conclusion it was shown that the solid-state complexes formed by poly(L-arginine), poly(L-histidine) and poly(L-lysine) cations and retinoic acid can be prepared as films and nano-particles. The high content of retino-ate moieties, the absence of crystallinity and low particle sizes could make these complexes interesting as a new carrier for the delivery of retinoic acid, either transdermal or in body fluids. It may be speculated that supramolecu-lar structures such as the smectic A-like nano-particles of the tart-type pre-... 

In oxidation reactions of ascorbic acid, homogentisic acid and hydroquinone by poly(l-histidine) — Cu(II) complex, the reaction profile shows a Michaelis-Menten type curve in the reaction condition of pH ranging from 5—6. These oxidation reaction rates are higher than the oxidation rates by the catalyst without poly(l-histidine). On the other hand, the rate of oxidation of a positively charged substrate, phenylenedi-... 

The significance of axial coordination sites of Cu(II) in poly(L-histidine)-Cu(II) complex for oxidation and reduction reaction is pointed out (106,107). A loosely axial coordinated Cu(II) ion gives a high activity. 

Lee ES, Oh KT et al (2007) Tumor pH-responsive flower-like micelles of poly(L-lactic acid)-b-poly (ethylene glycol)-b-poly(L-histidine). J Control Release 123 19-26... 

Earlier studies include those of Merrifield and Wooley (i27) and of Katchalski et al. (128). They prepared poly-L-histidine and its copolymers with other amino acids and showed them to be active in the hydrolysis of PNPA. Noguchi and Saito prepared poly-L-histidine, its copolymers with other amino acid residue (glutamic acid 2, aspartic acid 3, serine 4, alanine 5, cystein 6, lysine 7, e-aminocaproic acid S, and tyrosine 9), and various dipeptides containing the histidyl residue 1), (129,130). The... 

For example, Bae and coworkers reported pH-induced destabihzable poly (L-histidine) (PHis)-based micelles targeting the tumor acidic environment [140], PHis has a pH-dependent water-solubility as a result of protonation of the unsaturated nitrogen of its imidazole ring at low pH [141]. Its soluble/insoluble transition pH (pH,) is dependent on its molecular weight. PHis with a more than lOkDa... 

Asayama, S. Kawakami, H. Nagaoka, S. Design of a poly(L-histidine)-carbohydrate conjugate for a new pH-sensitive drug carrier. Polym. Adv. Technol. 2004, 15, 439 44. 

Another approach for polymeric micelles using pH-triggered drug release was reported by Lee et al., where an accelerated release of physically incorporated Dox in the micelle was achieved with a decrement of pH [63]. hi this report, a pH-sensitive polymeric micelle composed of a mixture of PEG-poly(L-histidine) as a pH-sensitive polybase possessing pKa values around the physiological pH and biodegradable PEG-poly(L-lactic acid) block copoly-... 

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