title: [Isolation and characterization of an unknown, leucine-rich 3.1-S-alpha2-glycoprotein from human serum (author's transl)].
abstract: This article describes the isolation and characterization of a previously unknown, leucine-rich 3.1S-alpha2-glycoprotein from human serum. The starting material was Supernatant II, which is a byproduct in the large-scale preparation of albumin and gamma-globulin by the ethacridine lactate/ammonium sulfate procedure. The purified protein is homogenous both in carrier-free and molecular-sieve electrophoresis. Its electrophoretic mobility indicates that it belongs to the alpha2-globulins. Isoelectric focussing splits it into 4 bands with isoelectric points between 3.8 and 4.1. In the ultracentrifuge it sediments in a single band at 3.1S. The molecular weight determined by equilibrium sedimentation is 49 600 +/- 4 000. Subunits were not detected. Chemical analysis reveals it to be a glycoprotein with a carbohydrate content of 23%. The amino acid content is unusual in that the leucine content is almost 17%, i.e. about every fifth amino acid is a leucine. The average concentration of the leucine-rich 3.1S-alpha2-glycoprotein in human serum was determined by a quantitative immunological method as 2.1 mg per 100 ml. The protein is not related to any of the previously known well characterized serum proteins.
mesh_terms: D000510:Alpha-Globulins / Q000302:isolation & purification*; D000596:Amino Acids / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D006023:Glycoproteins / Q000097:blood / Q000302:isolation & purification; D006801:Humans; D007930:Leucine / Q000032:analysis; D008970:Molecular Weight
chemical_list: D000510:Alpha-Globulins; D000596:Amino Acids; D002241:Carbohydrates; D006023:Glycoproteins; D007930:Leucine
vernacular_title: Isolierung und Charakterisierung eines bisher unbekannten leucinreichen 3.1S-alpha2-Glykoproteins aus Humanserum.