Studies on Indian silk. I. Macrocharacterization and analysis of amino acid composition

Abstract

This first in a series of articles characterized the different varieties of Indian silk for their macrostructural parameters, such as filament length, degumming loss, denier, cross section, moisture regain, and intrinsic viscosity, for example. The results of amino acid analysis using a reverse-phase technique were also reported. Five Indian silk varieties-two mulberry (bivoltine and crossbreed) and three nonmulberry (tasar, muga, and eri)-were investigated. The differences existing between the different varieties and the extent of lengthwise variations within a cocoon in the dimensional and macrostructural parameters were discussed. It was observed that denier of the filament decreases considerably from the outer to the inner layers, whereas density showed an increasing trend in all the varieties. Both the mulberry silks demonstrated lower moisture regain. Electron micrographs of all the nonmulberry varieties showed microvoids in their cross section. Fraction studies showed the development of mushroom structure on the tips. In both types of mulberry silk, glycine, alanine, and serine constitute about 82% of the amino acids present. On the other hand, in nonmulberry silks, these constitute about 73% with a high proportion of alanine. The nonmulberry varieties showed a substantial proportion of amino acids with bulky side groups. Similarly, the higher hydrophilic to hydrophobic amino acid ratio (9.06 -9.85) for nonmulberry silks, compared against that of the mulberry varieties (5.29 -6.22), was shown to be responsible for the higher moisture content of nonmulberry silks. Cystine and methionine were present in all the varieties. The higher intrinsic viscosity of nonmulberry varieties suggested their higher molecular weight. Through amino acid analysis, it was shown that there is no difference in chemical architecture between the outer and the inner layers of cocoons.

Structure and properties of cocoons and silk fibers produced by Hyalophora cecropia

“…The average weight of the cocoons used in this study was about 750 mg and cecropia cocoons with average weights of 800 mg-1 g were reported earlier [12]. Average cocoon weights of about 640 mg for mulberry silk, 3.4 g for A. mylitta, and 840 mg for P. ricini silks have been reported [2,3]. In another report, cocoon weights ranging from 7 to 14 g have been reported for A. mylitta cocoons [23].…”

“…The ratio of glycine/alanine for cecropia silk is 0.54, much lower than that of 1.5 for mulberry and 0.8 for the common wild silks. The amount of glycine and alanine determines the crystallographic form of the proteins [2,3]. The lower ratio glycine/alanine in cecropia suggests that cecropia silk has a considerably different crystallographic structure compared to mulberry and wild silks.…”

“…Cross-section of the fibers in Figure 6 reveals that the fibers are ribbon-like with a solid rectangular cross-section. The cross-section of the cecropia silk fibers are different than mulberry silk fibers which have a triangular shape but similar to the tasar (A. mylitta) and muga (A. assama) silk fibers [1][2][3]. Physical structure Figure 7 shows the X-ray diffractogram of cecropia and B. mori silk fibers.…”

“…However, wild varieties of silk such as tasar silk, produced by the insect Antheraea mylitta commonly found in India and Antheraea pernyi found in China; muga silk, produced by Antheraea assamensis; and eri silk, produced by Phylisomia ricini have been partially domesticated and used to rear silk for commercial applications [1][2][3]. Silks are known for their high strength, durability, luster, drapeability, and other unique features compared to the common cellulose and synthetic fibers in current use.…”

Protective Effect Of Aabresham (Bombyx Mori) Against Atherosclerosis

“…A part from anti oxidant, these quercetins have anti-inflammatory, anti atherogenic, anti coagulation and anti hypertensive effects too. 24,25 These compounds also inhibit smooth muscle cells proliferation, migration and improve vascular function. Flavonoids reduce lipid peroxidation by scavenging ROS, chelation of transition metal ions along with reducing macrophage oxidative stress by inhibition of cellular oxygenases or by activating cellular antioxidants such as glutathione system.…”