The Comparison of Free and Bound Amino Acids between Dry and Wet Types of Cerumen

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Abstract
The wet and dry types of normal cerumens obtained from healthy Japanese children at 7 to 12 years of age were fractionated into the following 4 fractions: Fractions I, II, III and IV were composed mainly of lipid, an unknown substance tentatively termed "substance X", free amino acids and protein, respectively. Identification and estimation of free amino acids in fractions II and III were made by means of ninhydrin reaction and dinitrophenylation, and bound amino acids of protein moiety of Fraction IV were determined after acid hydrolysis. The content of free amino acids were 4 times higher in the dry type of cerumen than in the wet type: it was 15 and 4% for the dry and wet types, respectively. Following 18 kinds of amino acid were identified commonly in the both types of cerumen, and no qualitative difference was seen between them: leucine, isoleucine, phenylalanine, valine, tryptophan, tyrosine, alanine, threonine, glycine, serine, glutamic and aspartic acids, glutamine, cystine, lysine, arginine, citrulline and proline. In the Fraction IV of both types, 15 amino acids were identified as follows: leucine, isoleucine, phenylalanine, valine, tryptophan, tyrosine, alanine, threonine, glycine, serine, glutamic and aspartic acids, cystine, lysine, and proline. No qualitative and quantitative differences were observed between the 2 types of the cerumen.