Follistatin, a myostatin‐inhibiting protein, is prohibited according to chapter S4 of the “WADA 2019 List of Prohibited Substances and Methods”. While currently no approved pharmaceutical formulations of follistatin are available, follistatin can be bought on the black market. Most of the products are labeled “follistatin 344” (FS344), a few “follistatin 315”. A study on FS344 black market products was performed and an electrophoretic detection method for serum and urine developed. While only nine of the 17 tested products actually contained follistatin, in some of the others growth promoting peptides were found (e.g. MGF, GHRP‐2). Surprisingly, all nine products contained His‐tagged FS344 and a high degree of its oligomers. The detection method is based on immunomagnetic purification followed by SDS‐PAGE and Western blotting with a monoclonal anti‐His antibody. Alternatively, a monoclonal anti‐follistatin antibody can be used. For immunoprecipitation (IP), a polyclonal anti‐follistatin antibody is applied. An evaluation of suitable antibodies for IP and immunoblotting is also presented. Furthermore, practically all currently available follistatin standards were investigated. The detection limit of the method for black market FS344 in urine is ca 0.1 ng/mL for 10 mL. For a sample volume of 100 μL, an LOD of 5 ng/mL could be achieved for serum. Due to the presence of His‐tags an unambiguous differentiation from endogenous follistatin is possible.

中文翻译：

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黑市卵泡抑素的检测344。

根据“ WADA 2019禁用物质和方法清单”的第S4章，禁止使用抑制肌生长抑制素的卵泡抑素。尽管目前尚无批准的卵泡抑素药物配方，但卵泡抑素可在黑市上购买。大多数产品标有“卵泡抑素344”（FS344），少数有“卵泡抑素315”。对FS344黑市产品进行了研究，并开发了一种用于血清和尿液的电泳检测方法。虽然17种测试产品中只有9种实际含有卵泡抑素，但在其他一些产品中发现了促进生长的肽（例如MGF，GHRP-2）。出乎意料的是，所有九种产品均包含带有His标签的FS344及其高度的低聚物。检测方法基于免疫磁性纯化，然后进行SDS-PAGE和单克隆抗His抗体的Western印迹。或者，可以使用单克隆抗卵泡抑素抗体。对于免疫沉淀（IP），应用了多克隆抗卵泡抑素抗体。还提出了针对IP和免疫印迹的合适抗体的评估。此外，几乎所有现有的卵泡抑素标准品均已进行了研究。尿液中黑市FS344方法的检测限为10 mL约为0.1 ng / mL。对于100μL的样品量，血清的LOD可以达到5 ng / mL。由于存在His标签，因此有可能与内源性卵泡抑素进行明确区分。应用了多克隆抗卵泡抑素抗体。还提出了针对IP和免疫印迹的合适抗体的评估。此外，几乎所有目前可用的卵泡抑素标准品均已进行了研究。尿液中黑市FS344方法的检测限为10毫升约0.1 ng / mL。对于100μL的样品量，血清的LOD可以达到5 ng / mL。由于存在His标签，因此有可能与内源性卵泡抑素进行明确区分。应用了多克隆抗卵泡抑素抗体。还提出了针对IP和免疫印迹的合适抗体的评估。此外，几乎所有目前可用的卵泡抑素标准品均已进行了研究。尿液中黑市FS344方法的检测限为10 mL约为0.1 ng / mL。对于100μL的样品量，血清的LOD可以达到5 ng / mL。由于存在His标签，因此有可能与内源性卵泡抑素进行明确区分。血清的LOD可以达到5 ng / mL。由于存在His标签，因此有可能与内源性卵泡抑素进行明确区分。血清的LOD可以达到5 ng / mL。由于存在His标签，因此有可能与内源性卵泡抑素进行明确区分。