家蚕の糞の遊離アミノ酸について

抄録

Eighteen kinds of the free L-amino acids found in extracts and hydrolysates of fasted silkworm feces, and those in the extracts of mulberry leaves were determined by microbiological assay. As the amount of histidine and serine in the extracts was equal to that in the hydrolysates and the amount of the others in the hydrolysates was more than that in the extracts, we concluded that histidine and serine were excreted in the free form and the other amino acids in the free and combined form. Monoamino-dicarxylic-acids, glutamic acid and aspartic acid, were found in a relatively higher amount, but sulphur-containing amino acids, cystine and methionine, were found in a small amount in silkworm feces and mulberry leaves. Histidine in the extracts and glycine in the hydrolysates were markedly abundant, these amino acids being about 26% of the total amino acids. There seemed to be direct relationship between the amount of the previous amino acids excreted and those taken from mulberry leaves, while there seemed to be certain parallel relationship between the amount of the other amino acids found in the feces and the body fluid and that of amino-acids contained in the mulberry leaves. These facts suggest us that histidine and glycine are biosynthesized from other compounds in silkworm body. It is interesting to found that glycine is excreted in high amount as glycine is involved in the biosynthesis of fibroin and abundantly accumulated in the silkworm body.