PrA (EC 3.4.23.25), encoded by PEP4 in S. cerevisiae, is the most important and massive proteolytic enzyme in yeast . During beer production, yeast cells release PrA, which breaks down proteins resulting in abundant amino acids in beer Many studies have shown that the deletion
of PEP4 gene in industrial brewer’s yeast helps beer maintain foam stability, as this decreases the concentration of PrA