High production and optimization of the method for obtaining pure recombinant human prolactin

Abstract Prolactin is a pituitary hormone that is involved diverse physiological functions, such as lactation, reproduction, metabolism, osmoregulation, immunoregulation, and behavior. Its level of glycosylation is low in vivo , which favors its expression in bacterial systems. In the present work recombinant human prolactin (rec-hPRL) was expressed from the p1813-hPRL vector in Escherichia coli strain in inclusion bodies with 530.67 mg of rec-hPRL per liter of induced bacterial culture. The solubilization and renaturation of rec-hPRL followed by two methods described in the literature for this protein: one with detergent and basic pH, and other urea and dialyses was done by studying. The protocol with detergent/basic pH was not successful, whereas protocol with urea/dialyses was obtained pure protein and this was optimized. Rec-hPRL was obtained in a soluble, pure and active form, when the sample was 8-fold concentrated in the solubilization phase, allowing 33% recovery, 3-fold more that the original method. The pure protein was obtained with 38.37 i. u./mg activity, which is three times greater than that of the PRL standard from the WHO. In conclusion, this work obtained the highest production of rec-hPRL, and concentrating the sample eight times in the solubilization stage was decisive for obtaining a highly concentrated, active protein for future work.