Yasaman Ahmadbeigi - Department of microbiology and microbial biotechnology, Faculty of life sciences and biotechnology, Shahid Beheshti University, Tehran, Iran.
Neda soleimani - Department of microbiology and microbial biotechnology, Faculty of life sciences and biotechnology, Shahid Beheshti University, Tehran, Iran.
Farzaneh Azizmohseni - Department of Biotechnology, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran
Zahra Amini-bayat - Department of Biotechnology, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran

Background and Aim : Endolysins are essential bacteriophage encoded enzymes in the lytic phage life cycle, which hydrolyze the host cell wall and are a good antibiotic substituent against Antibacterial resistance. The endolysins of Gram-positive bacteria infecting bacteriophages contain catalytic domain(s) and binding domain. Histidine-dependent Amidohydrolase Peptidase (CHAP) domain is one of the most active domains, which has Anti-Staphylococcus aureus activity.Methods : The chimeric protein that contains the CHAP domain and binding domain was expressed in BL۲۱(Gold). Bacterial cells were sonicated and the chimeric protein ammonium sulfate precipitation was optimized. Results : We confirmed the level of precipitated chimeric protein using SDS-PAGE. The highest level of chimeric protein precipitate was observed in ۱۰% ammonium sulfate concentration.Conclusion : In this study, ammonium sulfate precipitation of a new chimeric peptidoglycan hydrolase was done to prepare crude lysate for the next step of purification. Ammonium sulfate precipitation is a useful technique as the first step in protein purification because you can have quick, bulk precipitation of cellular proteins.

Histidine dependent Amidohydrolase Peptidase (CHAP), Chimeric protein, Ammonium sulfate precipitation, Endolysin