FIG 5.

PsGH28 is an exo-α-galacturonidase that liberates galacturonate from oligouronates. (A and B) Activity of PsGH28 against polygalacturonate (PGA), trigalacturonate (GalUA₃), and digalacturonate (GalUA₂) as shown by FACE analysis (A) and turnover of released galacturonate by uronate dehydrogenase in an enzyme-coupled assay (B). + and −, presence and absence of PsGH28, respectively; E, enzyme-only sample. Abbreviation: GalUA, galacturonate. Data shown in panel B are the mean initial rates from three replicates; error bars indicate the SEM. (C) FACE gel showing complete degradation of unsaturated trigalacturonate (ΔGalUA₃) into GalUA by PsGH105A and PsGH28. GalUA₃, GalUA₂, and GalUA were included as standards. + and −, presence and absence of substrate or enzyme, respectively.