Ryoichi Tsurutani

A novel method for the synthesis of kyotorphin, Tyr-Arg, and 3H-Tyr-Arg, catalyzed by tyrosyl-tRNA synthetase from Bacillus stearothermophilus

A novel method of dipeptide synthesis is described that can be carried out in aqueous solution and does not require complicated protecting and deprotecting procedures. An analgesic neuropeptide named kyotorphin, H-Tyr-Arg-OH, was synthesized from unprotected tyrosine and arginine in a new enzymatic reaction catalyzed by immobilized tyrosyl-tRNA synthetase from Bacillus stearothermophilus. The reaction could be a useful tool in the syntheses of radioisotope-labeled oligopeptides to be used in receptor binding assays. 3H-Kyotorphin was prepared by this method at a yield of 72% and could be used in receptor binding assays after a single chromatographic separation.

Reactions of the aminoacyl-tRNA synthetase-aminoacyl adenylate complex and amino acid derivatives. A new approach to peptide synthesis.

Several kinds of dipeptide derivative were shown to be formed by the reactions of the aminoacyl adenylate-aminoacyl-tRNA synthetase complex and amino acid ester or amide. It was shown that the peptide bond could be formed by aminoacyl-tRNA synthetases even in the absence of the ribosome.

Systemic 70% Deacetylated Chitin (DAC‐70) as a Treatment for MRL/lpr Murine Lupus; Reduction of Immunoglobulin Deposition in the Skin and Kidneys

To the Editor: Current therapy for systemic lupus erythematosus (SLE) includes corticosteroids, various immunosuppressants, and plasma exchange. However, there can be serious adverse reactions to these drugs. The authors have thus sought to develop a new and safe therapy for SLE. Chitin (1) is a polymer of D-glucosamine, beta-poly-Nacetyl D-glucosamine. From deacetylation ratio values, it has been possible to identify various derivatives of chitin, each with its own degree of immunopotentiating capacity; 70% deacetylated chitin (DAC-70) has been shown to be the most effective immuno-adjuvant (2). In this study, we assessed the use of systemic DAC-70 in treating MRL/lpr lupus mice (3). MRL/Mp-Ipr/lprmice (3), 5 week-old virgin females, were purchased from Charles RiverJapan, Inc. and maintained under specific pathogen free (SPF) conditions in the Experimental Animal House (room temperature, 25°C) of the Unitika Research and Development Center, Kyoto. Eight mice Fig. 1. a) DAC-70 treated mice skin samples show a remarkably reduced degree and/or virtually no staining for IgG at the DE]. (x40) b) The DE] of non-treated mice skin shows strong IgG linear deposition. (x40)

A New Slow-Releasing Drug Delivery System for Chemically Combined Cisplatin with Chitin for Intraoperative Local Application: An Experimental Study

In order to concentrate anticancer agents in residual cancer cells and to decrease side effects by supressing the systemic concentration of drug, we developed a new drug delivery system, Plachitin, for intraoperative local application after esophagectomy. Chitin and cisplatin were coupled by covalent bond, and in this system chitin was used as a carrier for cisplatin. Chitin is metabolized in the human body by enzymes such as lysozyme and is absorbed in 1–3 months. It is this slow breakdown of chitin that allows Plachitin to release cisplatin over a long period of time and deliver high concentrations of drug to local lesions.