Waizumi Kenji

水溶液からのＬ－ヒスチジンの結晶核形成機構を解明するため，pHをジャンプさせることによって得た幾つかの濃度の過飽和水溶液中から結晶核が形成されるまでの時間（誘導期tind）を測定した。測定された誘導期tindを用いて結晶核形成理論に基づいた速度論的解析を行った結果，それらの溶液中で形成された結晶核の表面張σ ，臨界核形成の自由エネルギーΔG *，臨界核の半径ｒ *，臨界核を形成する分子数ｎ など，結晶核形成に関する重要なパラメータの値を定量的に求めることができた。pH６〜pH７の間で行った実験からは，Ｌ－ヒスチジンの臨界核は数個から十数個程度の分子からなる半径１〜２nm程度であり，過飽和度が高くなるにつれて，その大きさは小さくなることが明らかになった。

Characterization of the blue protein in the shell pattern of Japanese littleneck clam (Ruditapes philippinarum ) was performed by purification using anion-exchange chromatography, amino acid analysis, molecular weight measurements, quantification of ferric ions, etc. Blue colored two components were found by anion exchange chromatography. The blue colored shell protein and the colorless mantle protein were found to be homologous to each other in amino acid composition; they are acidic proteins rich in aspartic acid and glutamic acid and that the isoelectric point of the blue protein was estimated as pI =3.96. The secondary structures of the blue protein were estimated as α-helix (28.6%), β-sheet (20.1%), and random coil (51.3%). From combination of molecular weight measurements and quantification of ferric ions, it was found that the blue protein is formed as trimer or tetramer from the monomer proteins of about 10 kDa by complexing with ferric ion. It was also found that there are two kinds of ferric ion existing states and that reducing agents decompose the blue colored trimer or tetramer into dimer or smaller units accompanying decolorization.