4-Guanidinobenzoic Acid Methanesulfonate is a salt form of 4-guanidinobenzoic acid, commonly used in biochemical and pharmacological research as a specific inhibitor of serine proteases, including trypsin, chymotrypsin, and plasma kallikrein. It facilitates the study of enzyme kinetics, mechanisms of action, and inhibition profiles in proteolytic pathways. This compound is valuable for developing novel enzyme inhibitors and therapeutic agents targeting diseases involving dysregulated proteolysis, such as inflammation, thrombosis, and cancer. It is also utilized in in vitro assays to assess enzyme activity and in preclinical evaluations for drug safety and efficacy.