Takashi Abiko

Isolation, structure and biological activity of the Trp-containing pentapeptide from uremic fluid.

Abstract Trp-containing pentapeptide was isolated from uremic fluid of an uremic patient by ultrafiltration with Amicon membranes followed by gel filtrations. The peptide thus obtained was identified as H-Asp-Leu-Trp-Gln-Lys-OH by amino acid analysis, manual Edman degradation method, physical constants and analytical data of synthetic pentapeptide. Structural similarity was soon realized between this peptide and pentapeptide moiety corresponding to position 123 through 127 of β-chain of fibrinogen. E-rosettes inhibition test was shown this pentapeptide to have an inhibition activity by amount more than l.Omg/ml.

Inhibition effect of rosette formation between human lymphocytes and sheep erythrocytes by specific heptapeptide isolated from uremic fluid and its analogs

Abstract One of middle molecular substances (H-His-Pro-Ala-Glu-Asn-Gly-Lys-OH) and its two analogs, in which the proline residue in position 2 was replaced by glycine and the alanine residue in position 3 was replaced by valine exert a inhibition effect on in vitro E-rosette formation. Its synthetic two analogs showed diminished biological activity compared to native heptapeptide.

Functional Roles of Phenylalinine7 of Thymic Humoral Factor-γ2 in the Impaired Blastogenic Response of Uremic T-Lymphocytes

The peptide analogs of thymic humoral factor-gamma 2 (THF-gamma 2) in which phenylalanine residue at the 7th position are replaced by phenylglycine (Phg), homophenylalanine (Hph), and 1-naphthylalanine (1-Nal) were synthesized by a solid-phase method and the immunological significance of the aromatic amino acid of this position was comparatively investigated. The in vitro restoring effect of the synthetic peptides on the impaired phytohemagglutinin (PHA) response of T-lymphocytes from uremic patients was tested. The observed activities of these peptides were in order (1-Nal7) thymic humoral factor [THF]-gamma 2 > 4-Fluoro (Phe7) THF-gamma 2 > THF-gamma 2. However, the other two analogs, [Phg7] THF-gamma 2 and [Hph7] THF-gamma 2, had no restoring effect even at a higher concentration.

Synthesis of an immunologically active analog of thymic humoral factor-γ 2 with enhanced enzymatic stability

Acetyl-thymic humoral factor-gamma 2 chloromethyl ketone [Ac-Leu-Glu-Asp-Gly-Pro-Lys-Phe-Leu-CH2Cl], an analog of thymic humoral factor-gamma 2, was synthesized and studied for its immunological effects on the impaired blastogenic response of T-lymphocytes isolated from uremic patients. Synthetic thymic humoral factor-gamma 2 and the synthetic acetyl-thymic humoral factor-gamma 2 chloromethyl ketone both restored the impaired blastogenic response of T-lymphocytes of uremic patients. However, the synthetic thymic humoral factor-gamma 2 is susceptible to proteolytic digestion. On the other hand, the synthetic acetylthymic humoral factor-gamma 2 chloromethyl ketone retained activity and was shown to exhibit a high degree of stability when incubated in human serum, These results indicate that N-terminal acetylation and the introduction of a chloromethyl ketone residue into the C-terminal residue of thymic humoral factor-gamma 2 increase resistance to proteolytic degradation by exopeptidases without loss of immunological activity.

Synthesis of [Phe(4F)3]thymopoietin II and examination of its immunological effect on the impaired blastogenic response of T-lymphocytes of uremic patients

[Phe(4F)3]thymopoietin II was synthesized using a conventional solution method. The deprotection of the protected [Phe(4F)3]thymopoetin II was achieved by treatment with 1 M trifluoromethanesulfonic acid:thioanisole (molar ratio 1:1) in trifluoroacetic acid in the presence of dimethylselenide and m-cresol. The synthetic f1p4(4F)3]thymopoietin II and thymopoietin II were tested for effect on impaired T-lymphocyte transformation by phytohemagglutinin in uremic patients suffering from recurrent infectious diseases. The restoring activity on the impaired phytohemagglutinin stimulation of T-lymphocytes was obtained after incubation of peripheral lymphocytes isolated from uremic patients with the synthetic [Phe(4F)3]thymopoietin II. This peptide exhibited far stronger restoring effect than that of our synthetic thymopoietin II.

Synthesis of a new biological response modifier thyrnosin β4 analogue and its restorative effect on depressed

Thymosin β4 is a polypeptide isolated from thymosin fraction 5. This peptide exhibits important activities in the regulation and differentiation of thymus-dependent lymphocytes. An analogue of thymosin β4, [Phe(4F)12] deacetyl- thymosin β4, was synthesized by a solution method, followed by deprotection with 1 M trifluoromethanesulphonic acid (TFMSA)-thioanisole (molar ratio, 1:1) in trifluoroacetic acid (TFA) in the presence of dimethlselenium. Finally, the deprotected peptide was incubated with dithiothreitol to reduce sulphoxide on the methionine side chain. The synthetic [Phe(4F)12]deacetyl-thymosin β4 was found to have a restoring effect on the impaired blastogenic response of T-lymphocytes isolated from uraemic patients with recurrent infectious diseases. This analogue exhibited stronger restorative activity than that of our synthetic deacetyl-thymosin β4.

Synthesis of [I-NaI3]] thymopoietin II and examination of its immunological effect on the uremic T-lymphocytes.

A TP II analogue, [1-Nal3] TP II, was synthesized by a conventional solution method, followed by deprotection with 1M TFMSA-thioanisole (molar ratio 1:1) in TFA in the presence of Me2Se and m-cresol as scavengers. The synthetic [1-Nal3] TP II, TP II and [Phe (4 F)3] TP II were tested for comparative effect on the impaired T-lymphocyte transformation by PHA in uremic patients suffering from recurrent infectious diseases. The synthetic analogue was found to have stronger restorative activity than those of our synthetic TP II and [Phe (4F)3] TP II.

Functional roles of Phe12 of deacetyl-thymosin β4 in the impaired blastogenic response of uraemic T-lymphocytes

Phe12 of deacetyl-thymosin β4 is one of the structural essentials for restorative effect on the impaired blastogenic response of uraemic T-lymphocytes. In order to evaluate the functional roles of this phenyl group in the restorative effect on impaired T-lymphocytes, two analogues, [1- Nal12]deacetyl-thymosin β4 and [Cha12]deacetyl4 thymosin β4, were synthesized by a solid-phase method and evaluated for restorative effect on the impaired blastogenic response of uraemic T-lymphocytes. The results indicated that [1-Nal12]deacetyl-thymosin β4 which had a bulky naphthyl ring showed a stronger restorative effect than that of deacetyl-thymosin β4, but it was slightly weaker than that of [Phe(4F)12]deacetyl-thymosin β4. However, [Cha12]deacetyl-thymosin β4 showed no restorative effect on the impaired blastogenic response of uraemic T-lymphocytes.

Solid-phase syntheses of two deacetyl-thymosin β4 analogues with substitution at position 12 and their effects on impaired blastogenic response of T lymphocytes of uremic patients

AbstractTwo deacetyl-thymosin β4 analogues containing Phe(4Br) or D-Phe(4Br) as position 12 were synthesized by the manual solid-phase method, and their immunological effects on the impaired blasto...

Syntheses of thymopoietins and their immunological effects: Relationship of amino acid sequence to immunological activity

Peptides and fragment analogs of the thymopoietin (TP) family have been synthesized using conventional synthesis in solution and tested for immunological effects on the impaired lymphocytes of uremic patients. These studies indicate that the Arg-residue of the sequence 32 to 36 of thymopoietin II is necessary for restoring activity of E-rosette formation on reduced E-rosette formation in uremic patients and the shortest peptide fragment of thymopoietin II (thymopentin), Arg-Lys-Asp-Val-Tyr, increased the activity of E-rosette-forming cells similarly to the longer chain of thymopoietin fragments containing thymopentin in their sequences. The synthetic human thymopoietin (hTP) showed restorative effect on the impaired T-lymphocyte activity of uremic patients as well as the synthetic two other synthetic thymopoietins, bovine thymopoietin I (bTP-I) and bovine thymopoietin II (bTP-II). However, the restoring activity of the synthetic bovine thymopoietin III (bTP-III or bovine splenin) was lower than that of the synthetic bTP-I. A synthetic analog of human splenin (hSP), [Glu34]hSP showed an enhancing effect on the reduced B-lymphocytes of uremic patients.