Hiromi Yamada

Identification of fibroin-derived peptides enhancing the proliferation of cultured human skin fibroblasts

We previously reported that the fibroin of the silkworm Bombyx mori enhanced the proliferation of cultured human skin fibroblasts. In this work, the fibroin was digested by chymotrypsin, and the resulting peptide fragments were fractionated and assayed for their biological activity. Two peptides that promoted fibroblast growth were isolated and identified to be VITTDSDGNE and NINDFDED. Both sequences are found in the N-terminal region of the fibroin polypeptide and are thought to be the active principle of fibroblast growth-promoting activity.

Silkworm requires 3,4-dihydroxybenzene structure of chlorogenic acid as a growth factor

Abstract On the chlorogenic acid for its growth promoting activity to silkworm, Bombyx mori , the constituents of the depside and their analogues were tested in their activity. Ortho-dihydroxybenzene structure was found to be the active part of the chlorogenic acid molecule. Phenylalanine, tyrosine and dihydroxyphenylalanine could not replace chlorogenic acid during the growth of silkworm. The authors propose to define chlorogenic acid as a kind of vitamins for silkworm, Bombyx mori .

Immobilization of β-Tyrosinase Cells with Collagen

β-Tyrosinase (tyrosine phenol-lyase: EC 4.1.99.2) catalyzes the stoichiometric conversion of L-tyrosine to pyruvate, ammonia and phenol, and requires pyridoxal phosphate (PLP) as a cofactor (1–3). Apparently homogeneous preparations of the enzyme were prepared by us from cells of Escherichia intermedia (4,5) and Erwinia herbicola (6) grown in media supplemented with L-tyrosine (7). We have reported that crystalline preparations of the enzyme catalyze a series of α,β-elimination (Eq. 1 and 2) β-replacement and racemization (Eq.6) reactions (8–11). The reverse of the α,β-elimination reaction to synthesize L-tyrosine or L-dopa (Eq. 7,8) was also catalyzed by crystalline preparations of the enzyme (12).