Amino acid composition of human nasal mucus. Normal subjects.

Abstract

A profile of the proportions of the amino acids of the nasal secretion will enhance our understanding of nasal physiology. For the clinician, today this might be an interesting fact especially because this mucous secretion differs from mucous secretions produced elsewhere. For the future, it might be worked into the practical aspects of clinical practice. For the researcher, it furnishes another step in building the complete picture of nasal physiology. To supply this information nine composites from 55 individual specimens of nasal secretion from normal persons were subjected to acid hydrolysis and quantitative amino acid estimation. Sixteen amino acids were found regularly. Analytical recovery factors were determined for the individual amino acids, and, from these, mole percentages in the original mucus were estimated. The 16 amino acids in order of decreasing abundance were: proline, glutamic acid, glycine, serine, leucine, lysine, alanine, threonine, aspartic acid, valine, arginine, phenlyalanine, tryptophan, tyrosine, isoleucine and histidine. In the nasal mucus, a relatively high proline content is balanced by a relatively lower content of threonine and serine than in other types of mucus. Compared with the proportions of free amino acids in blood plasma, the nasal mucus has a much higher content of the dicarboxylic glutamic and aspartic acids, and a much lower content of alanine and valine.