title: Detection of His-tagged Long-R³-IGF-I in a black market product.
abstract: OBJECTIVE
  Performance-enhancing substances are illicitly used in elite or amateur sports and may be obtained from the black market due to a cheaper and easier availability. Although various studies have shown that black market products frequently do not contain the declared substances, enormous amounts of illegally produced and/or imported drugs are confiscated from athletes or at customs with alarming results concerning the outcome of the analyses of the ingredients. This case report describes the identification of His-tagged Long-R³-IGF-I, which is usually produced for biochemical studies, in an injection vial.
  
  
  METHODS
  The ingredients were isolated by immunoaffinity purification and identified by nano-UPLC, high-resolution/high accuracy mass spectrometry of the intact and trypsinated substance and by an enzyme-linked immunosorbent assay.
  
  
  RESULTS
  (Tandem) mass spectra characterized the protein as Long-R³-IGF-I with a His₆-tag attached to the C-terminus by the linker amino acids Leu-Glu.
  
  
  CONCLUSIONS
  His-tags are commonly added to proteins during synthesis to allow a convenient and complete purification of the final product and His-tags are subsequently removed by specific enzymes when being attached to the N-terminus. The effects of His-tagged Long-R³-IGF-I in humans have not been elucidated or described and the product may rather be a by-product from biochemical studies than synthesized for injection purposes.
authors.affiliation: Institute of Biochemistry/Center for Preventive Doping Research, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: Maxie
authors.initials: M
authors.lastname: Kohler
authors.forename: Andreas
authors.initials: A
authors.lastname: Thomas
authors.forename: Katja
authors.initials: K
authors.lastname: Walpurgis
authors.forename: Koen
authors.initials: K
authors.lastname: Terlouw
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schänzer
authors.forename: Mario
authors.initials: M
authors.lastname: Thevis
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D006639:Histidine / Q000032:analysis*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000031:analogs & derivatives* / Q000032:analysis; D008969:Molecular Sequence Data; D058573:Performance-Enhancing Substances / Q000032:analysis*; D015813:Substance Abuse Detection; D053719:Tandem Mass Spectrometry
chemical_list: D058573:Performance-Enhancing Substances; C085700:long R(3)-insulin-like growth factor-I; C033223:polyhistidine; D006639:Histidine; D007334:Insulin-Like Growth Factor I