| 抄録・内容（日） | 1. はじめに : 絹糸は通常カイコガ(Bombycidae)に属する家蚕(Bombyx mori)のつくるまゆをさしているが, カイコ以外にも鱗翅目昆虫にはまゆをつくるものが多く, ヤママユガ科(Saturniidae)に属するシンジュ蚕(Attacus pernyi), エリ蚕(Attacus ricini), 柞蚕(Antheraea pernyi), タッサー蚕(Antheraea mylitta), ムガー蚕(Antheraea assama), 天蚕(Antheraea yamamai), クス蚕(Dictyoploca japonica)などのつくるまゆの繊維もあり, さらにその他Thanmetopoeinae科に属するアナフ属のつくるまゆの繊維や, Naphila madagascariensisのクモ絹, Pinna nobilis二枚貝の海絹などもある。 |
| 抄録・内容（英） | Silk is a natural polyamide fiber (chain polymer formed by the condensation of α-amino acids) spun by the silk worm. It has a comparatively high degree of crystallinity (60-70%), and its delicate fine texture, elegant luster, and excellent feeling are unique. However, it has the disadvantage of easily producing dyeing speck, yellowing and lousiness, The gelatinous sericin which cover the fibroin fibers is composed mainly of acidic, basic and oxyamino acids which have polarity, and differ greatly from the highly crystalline fibroin which is composed mainly of amino acids without polarity. In the present investigation a comparative study of the sericin of domestic silk worms and that of wild silk worms was made, and it was found that thc sericin of domestic silk worms, generally, contain more non-polar amino acids that of wild silk worms; also, that although the sericin of wild silk worms contain more polar amino acids than that of domestic silk worms, the former contains large amounts of tannin and ash, and consequently, the solubility of the sericin of wild silk worms is lower than that of the sericin of domestic silk worms. A comparative study of the fibroin filaments of domestic silk worms and that of wild silk worms was also made and it was found that the fibroin of domestic silk worms contains considerably more glycine than alanine, and is composed mainly of glycine, alanine, serine and tyrosine, whereas, the fibroin of wild silk worms contains considerably more alanine than glycine, and is composed of aspartic acid and arginine, also, besides glycine, alanine, serine, and tyrosine. Furthermore, the presence of a highly crystalline non-fibrous protein (1.5-3.0%) which is soluble in a strong alkaline solution and essentially different from sericin has been detected detween the fibrils. The aforementioned results of our studies indicate that there is a specific specificty in the amino acid composition of silk protein of various species of silk worms, and this difference in the amino acid composition together with the difference in the texture of the sillk fibers influence the dyeing, degummiug, and finishing process of silk. The dyeing affinity of sericin is generally, higher than that of fibroin. This is especially true when dyeing in acid dye daths with anion dyes, such as, acid dyes, direct dyes and acid chrome dyes which dye mostly by ionic linkage. In most cases, sericin is removed by deumming, however, under present conditions of degumming, the difference in solubility of sericin and fibroin in alkaline solutions is taken advantage of, and heat treatment, particularly using soap or sodium silicate, is performed which very often result in damage to the fibers, and causing sericin to remain unevenly on the surface of the fibers. These disadvantages may be obviated by a degumming process in which protease which selectively hydrolyses sericin is used. In the present study, no definite relation was found between dyeing affinity and the amino acid composition of protein, in the dyeing of fibroin fibers of domestic silk and wild silk. However, the ratio of the amount of serine to the amount of bulky amino acids which have a benzene nucleus like tyrosine constituting the amorphous region of the principal amino acid compositions of silk protein, viz., glycine, alanine, serine, and tyrosine, or in other words, the size of the microcrystalline pores, greatly influences the dyeing affinity of silk. Also, influencing the dyeing affinity are the orientation of the protein molecular aggregate, also, the size of the paracrystalline state of the internal micro-structure of the fibrils. |
