Quantitation of some amino-terminal residues in proteins using 3H-labelled dansyl chloride and 14C-labelled amino acids.
A method for quantitation of amino-terminal residues in proteins is presented. The method is a modification of a double isotope-labelling technique, using 3H-labelled dansyl chloride and 14C-labelled amino acids as internal standards. The method is demonstrated on human fibrinogen, horse myoglobin and on mouse myoloma IgA. A linear relationship between the ratio 3H/14C in the separated amino-terminal amino acid of the protein and the amount of protein added in the labelling mixture was obtained with standard deviations of +/- 7.4% +/- 3.4% and +/- 10.3%, respectively. An application of the method is demonstrated by measuring the increase in amino-terminal glycine in fibrinogen following the proteolytic action of thrombin. The method seems to be useful when 0.1 nmol or more of protein is used.
D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D002250:Carbon Radioisotopes; D003619:Dansyl Compounds; D005340:Fibrinogen / Q000032:analysis; D006736:Horses; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007553:Isotope Labeling / Q000379:methods*; D009194:Myeloma Proteins / Q000032:analysis; D009211:Myoglobin / Q000032:analysis; D011506:Proteins / Q000032:analysis*; D014316:Tritium
D000596:Amino Acids; D002250:Carbon Radioisotopes; D003619:Dansyl Compounds; D007070:Immunoglobulin A; D009194:Myeloma Proteins; D009211:Myoglobin; D011506:Proteins; D014316:Tritium; D005340:Fibrinogen