絹フイブロインの酸化剤による崩壊に関する研究

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The degradation of fibrous protein, "silk fibroin" is chiefly due to the hydrolytic and oxidative actions, however, apart from the considerable amount of work on the former action, little has been done systematically on the latter. Therefore, the author treated silk fibroin respectively with three oxidizing agents, i.e. potassium permanganate, calcium hypochlorite and hydrogen peroxide to obtain the different levels of degradation. Changes of physical, physico-chemical and general-chemical properties and then fine structures of fibroin were studied systematically.(1) The quality changes of dilute aqueous solutions of organic low molecules such as tyrosine, phenol, rhamnose and glucose and of high molecules such as fibroin, albumin, polypeptone, gelatin and soluble starch when 0.1 N potassium permanganate was dropped onto them each and the dialysis behaviors of those oxidized solution were observed, and the formation of complex due to the binding of reduced Mn to oxidized high molecules was recognized. After preparing of Mn-fibroin complex with different levels of oxidation, the average molecular weight of these complex was determined by light scattering measuring and it was apparently recognized that the molecular weight of complex formed by the light level of oxidation was much larger than that of untreated fibroin and that increase with the progress of oxidation. The fact indicates the formation of chelating complex containing manganese and tyrosine residue as a cross linkage on the oxidation of fibroin aqueous solution with potassium permanganate.(2) Fibroin fibre which was oxidized by dilute potassium permanganate solution at room temperature alters to brownish fibre and increases its weight. It was recognized that the colouring and weight increase in the light level of oxidation were due not to the adhesion of manganese dioxide but to the formation of Mn-fibroin chelating complex as the result of microscopic observation of oxidized fibroin fibre and the constant ratio of reduced Mn values to weight increment values and moreover the binding formula of cross-linkage was postulated. Although brownish oxidized fibroin fibre was decolourized (demanganesed) by washing with dilute hydrogen peroxide or oxalic acid, the former being accompanied with a little degradation, while the latter little. Demanganesed fibroin after oxidation of light level indicated scarcely the change in weight from that of the original, however, the degree of weakening in tensile strength and elongation was remarkable even in the substance which was oxidized in a short time and it was observed gradually increasing with the passage of time. During the oxidation, fall in tyrosine content and no change in total nitrogen and hydroxyl amino acid content were recognized and then a linear relationship between tyrosine content and reduced potassium permanganate was found by plotting the former against the latter. Although untreated fibroin is easy soluble in cupriethylene diamine (Cu-En), while demanganesed fibroin after oxidation is not the case under the same condition. Owing to this fact, it has been conceived to be insoluble in the solvent. Finding out the solubilizing condition of oxidized fibroin, the author could perform his studies on them in solution state. From those investigations decrease in viscosity and axis-ratio and increase in molecular weight with oxidation were noticed, but increase in molecular weight was remarkable in a short time of oxidation and after a while the gradual decrease was observed. Therefore, it was postulated that decrease in viscosity and in axis-ratio is to be attributed rather to the lateral aggregation of oxidized fibroin molecule due to partly tightening of the intramolecular binding, that is due to changes in molecular shapes than to the scission of main chains. Moreover, the aggregates were conceived to be polydisperse because of the flattening of electrophoretic patterns by oxidation. (3) The oxidizing velocity of fibro
鹿児島大学の論文
1962-03-25

絹フイブロインの酸化剤による崩壊に関する研究

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