Catalysis of Transamidation Reactions by Proteolytic Enzymes

Beef liver esterase as a catalyst of acyl transfer to amino acid esters

“…That chymotrypsin can catalyze acyl transfer from suitable substrates to the -amino group of amino acid residues has long been known (Johnston et at., 1950b; Blau and Waley, 1954). Chymotrypsin, however, is much less effective as a catalyst of such transamidation reactions than papain or ficin (Johnston et al, 1950a;Dowmont and Fruton, 1952;Mycek and Fruton, 1957; Brubacher and Bender, 1966), whose catalytic action involves the intermediate acylation of a cysteine residue (Stockell and Smith, 1957; Lowe and Williams, 1965; Kirsch and Igelstrom, 1966). Even more effective in this regard is beef spleen dipeptidyl transferase, an oligomeric thiol enzyme (Metrione et al, 1966) which catalyzes the polymerization of dipeptide amides (or esters) with high efficiency (Jones et al, 1952;Nilsson and Fruton, 1964; Heinrich and Fruton, 1968).…”

The Enzymic Condensation of a Thiol Ester-Type Carboxyl-activated Acylamino Acid with an Amino Acid Amide to Form a Peptide*

“…The BGTEE was prepared by a method which has been previously described (Johnston, 1956). The papain was prepared according to the method of Grassmann (1935) from crude dried papaya latex obtained from Wallerstein Laboratories.…”

“…(1955) have shown that ox brain and ox liver contain thiolesterases. In 1956 in this laboratory it was demonstrated that the plant proteolytic enzyme papain possessed powerful thiolesterase activity (Johnston, 1956). Papain was shown to catalyze the hydrolysis of benzoylglycine thiol ethyl ester (BGTEE)1 and benzoylglycine thiol isopropyl ester as well as benzoylglycine ethyl ester.…”

Biochemical reactions

“…(h) Transpeptidation (38,39) is the biological replacement of one component of a peptide bond by another organic radical. This reaction leads to the formation of polypeptides and proteins.…”