Identification of Peptides and Proteins in Illegally Distributed Products by MALDI-TOF-MS

Abstract

An analytical strategy based on matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) for identification of peptides and proteins in illegally distributed products is presented. The identified compounds include human growth hormone (hGH), human somatoliberin, anti-obesity drug (AOD), growth hormone releasing peptides (GHRP-2 and GHRP-6), Glycine-GHRP-2 and Glycine-GHRP-6, ipamorelin, insulin aspart and porcine, delta sleep-inducing peptide (DSIP), thymosin β4, insulin like growth factor (IGF), mechano growth factor (MGF), human chorionic gonadotropin (hCG), melanotan II, bremelanotide, dermorphin and body protecting compound (BPC 157). The identification of proteins was mainly based on peptide mass fingerprinting, i.e., bottom up approach, while the smaller peptides were identified through de-novo sequencing. In cases when a reference standard was available, complementary identification was performed by capillary electrophoresis in double-injection mode (DICE), where a suspicious product was compared with the reference standard through two consecutive injections within the same electrophoretic run.

Detection and quantification of the metabolite Ac‐Tβ1–14 in in vitro experiments and urine of rats treated with Ac‐Tβ4: A potential biomarker of Ac‐Tβ4 for doping tests

“…11 In another study, from the analysis of illegally confiscated peptides and proteins, they also analyzed after trypsin digestion of Ac-Tβ4. 22 Other researchers also reported that LAP could break down the K-T bond of TB-500 (Ac-LKKTETQ) in in vitro experiment to generate Ac-LKK peptide metabolite. 18 Recently, we reported that the metabolite Ac-Tβ 1-14 was produced in vitro by enzymatic reaction in K-S bond (between positions 14 and 15 of Ac-Tβ4).…”

“…Huang et al reported the presence of Ac‐Tβ4 in the wound by digesting wound tissues with trypsin for analysis with MALDI‐TOF MS and found the Ac‐Tβ 1–14 fragment because of a trypsin digestion of Ac‐Tβ4 11 . In another study, from the analysis of illegally confiscated peptides and proteins, they also analyzed after trypsin digestion of Ac‐Tβ4 22 . Other researchers also reported that LAP could break down the K–T bond of TB‐500 (Ac‐LKKTETQ) in in vitro experiment to generate Ac‐LKK peptide metabolite 18 .…”