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Relevant academic research and scientific papers

A 12-porphyrin system: Syntheses of peptide porphyrins with multiple histidines and the aggregation behavior in the presence of hemin

We succeeded in combining multiple-histidine peptides with porphyrins; that is to say, we synthesized three peptide porphyrins consisting of α4- meso-tetrakis(o-aminophenyl)porphyrin, α4-H2TAPP, and amphiphilic peptide, α4(PepA18)(n)(AG)(4-n)-H2TAPP (n = 1, 3, and 4; PepA18 = EEALEKHEKALEKHEKAG), in the liquid phase. These compounds were designed to construct multiple porphyrin systems; in other words, each peptide attached on the H2TAPP was designed to contain two histidines. The stability of the porphyrins, (AG)4-H2TAPP and (AG)1(Boc-AG)3-H2TAPP, as well as the coupling conditions between the porphyrin fragments and the 16-residue peptide, EEALEKHEKALEKHEK, to give α4-(PepA18)(n)(AG)(4-n)-H2TAPP (n = 1, 3, and 4) were studied in detail with respect to the temperature, solvents, coupling reagents, additives, and amines. This search revealed that the combination of DMF/benzotriazol-1-yl-oxytris(pyrrolidino)phosphonium hexafluorophosphate (PyBOP)/N,N-diisopropylethylamine is suitable for the purpose. The search also clarified that it is possible to synthesize α4- (PepA18)4-H2TAPP and α4-(PepA18)3(AG)1-H2TAPP selectively by choosing the coupling additives 1-hydroxy-7-azabenzotriazole (HOAt) and 1- hydroxybenzotriazole (HOBt, respectively. All of the compounds showed 40% helicity in a solution (phospate buffer, pH = 7.0) containing 2,2,2- trifluoroethanol (TFE). The UV-vis and circular-dichroism spectrophotometric titrations of Fe(III) protoporphyrin IX chloride, B, with α4(PepA18)4- ZnTAPP, A, indicated that up to three equivalents of B were incorporated into A in a buffer solution containing 15% TFE. Sedimentation-equilibrium ultracentrifugation experiments showed that A is a dimer in the solution, and that this dimer is transformed to a trimer when B is incorporated into A. These results suggest that A achieves a 12-porphyrin system consisting of different kinds of metalloporphyrin.

Synthesis of thymosin α1

Thymosin α1, was chemically synthesized by the fragment condensation of the protected amino terminal tetradecapeptide with the protected carboxyl terminal tetradecapeptide and by solid phase peptide synthesis. Thymosin α1 is active as an agent which affects regulation, differentiation and function of thymus dependent lymphocytes (T cells).

[Asn2 ]-thymosin α1 and analogs thereof

Thymosin α1, was chemically synthesized by the fragment condensation of the protected amino terminal tetradecapeptide with the protected carboxyl terminal tetradecapeptide. Similarly prepared was the analog [Asn2 ]-thymosin α1 utilizing the appropriately modified protected amino terminal tetradecapeptide. Both products are active as agents which affect regulation, differentiation and function of thymus dependent lymphocytes (T cells).