Physical Chemical, Immunological and Biological Characterization of Arapaima 2 gigas Follicle-Stimulating Hormone (ag-FSH) synthesized in HEK293 Cells

The cDNA sequences of the common gonadotrophic hormone α-subunit (ag-GTHα) and 13 of the specific follicle-stimulating hormone β-subunit (ag-FSHβ) of the giant Amazonian fish Ara-14 paima gigas, have been previously isolated by our research group. A synthesis of ag-FSH in HEK293 15 cells and its purification and preliminary characterization were also carried out. In the present work, 16 ag-FSH was obtained and purified from the same host cells and an extensive physical chemical 17 characterization was performed via RP-HPLC, HPSEC and MALDI-TOF-MS. Ag-FSH, when com-18 pared to human FSH (hFSH), showed a higher hydrophobicity by RP-HPLC and a higher molecular 19 mass (MM) via HPSEC. The same higher MM was also confirmed via MALDI-TOF-MS: 35,353 Da 20 for ag-FSH against 31,969 Da for hFSH. Its immunological activity was also confirmed via an hFSH 21 ELISA, in comparison with the highly purified pituitary preparation of hFSH-AFP7298A, from the 22 National Hormone and Pituitary Program (NHPP-USA). Finally, an in-vitro bioassay, based on the 23 stimulated release of 11-ketotestosterone (11-KT) from immature A. gigas testis, quantified its bio-24 logical activity in comparison with human chorionic gonadotropin (hCG) and with the WHO Inter-25 national Standard of recombinant hFSH (NIBSC-08/282) This suggests that injections of ag-FSH in 26 A. gigas and ag-FSH cDNA Gene Therapy applications should improve the reproductive functions 27 of this threatened species.