Problem: Plasma factors of blood coagulation are exposed to post-translational modification with the participation of vitamin K. It is necessary as a cofactor in the enzyme system of γ-carboxylation of protein factors of blood coagulation due to the increased affinity of their molecules with calcium ions. What amino acid is carboxylated in these proteins? Need Assignment Help? a. Phenylalanine b. Valine c. Arginine d. Serine e. Glutamic acid