title: Prothymosin alpha in human blood.
abstract: The major cross-reacting peptide in human plasma detected with a radioimmunoassay (RIA) for thymosin alpha 1 was identified as prothymosin alpha, based on its elution properties in gel-filtration chromatography and its amino acid composition after purification by HPLC. A small quantity (less than 10%) of the total cross-reacting material was recovered in fractions corresponding to lower molecular weight thymosin alpha 1-like peptides. The total quantity of cross-reacting material detected in human blood, expressed as thymosin alpha 1 equivalents, was 11-14 pmol/ml (approximately 90% was recovered in the leukocyte fraction, approximately 10% was in the plasma fraction, and 1-2% was in the erythrocyte fraction). The peptide present in leukocytes was also identified as prothymosin alpha. After correction for the 5-times lower molar reactivity of prothymosin alpha in the thymosin alpha 1 RIA employed in these experiments, we estimate that the content of prothymosin alpha in human blood is 55-70 pmol/ml (0.6-0.8 microgram/ml). The relatively small quantities recovered in the erythrocyte and plasma fractions may be attributed to contamination of the former by leukocytes or to leakage from leukocytes into the plasma.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D004912:Erythrocytes / Q000032:analysis; D006801:Humans; D007962:Leukocytes / Q000032:analysis; D010949:Plasma / Q000032:analysis; D011498:Protein Precursors / Q000097:blood* / Q000276:immunology; D011863:Radioimmunoassay; D000077596:Thymalfasin; D013947:Thymosin / Q000031:analogs & derivatives* / Q000097:blood / Q000276:immunology
chemical_list: D000596:Amino Acids; D011498:Protein Precursors; C040782:prothymosin alpha; D013947:Thymosin; D000077596:Thymalfasin