Comparing extracellular enzymatic hydrolysis between plain peptides and their corresponding analogs in the northern Gulf of Mexico Mississippi River plume

摘要: Abstract Peptide analogs, such as leucine-methylcoumarinylamide (Leu-MCA) and Lucifer yellow anhydride-tetraalanine (LYA-Ala4), are often used proxies to quantify extracellular peptidase activities, but how accurately these analogs represent natural peptides remains unclear. Here we compared hydrolysis rates of tetrapeptides alanine-valine-phenylalanine-alanine (AVFA) tetraalanine (Ala4) with their corresponding LYA along a salinity gradient in the northern Gulf Mexico Mississippi River plume. Hydrolysis were generally similar, not always, between plume water. For example, similar LYA-AVFA AVFA at all stations except one. In contrast, LYA-Ala4 significantly higher than those Ala4 low-salinity (18–19) stations, lower one high-salinity (36) station. These results suggest that relative activities different types peptidases, measured by or peptides, depended on biological chemical properties each station, abundance certain “opportuni-trophic” bacteria, including Flavobacterium , Ruegeria Roseobacter . The produced fragments amino acids from peptide implied further pathway specific substrate, tag affected pathway. Taken together, this study validates technique using enzymatic particularly overall rate, provides insights into patterns estuarine environments.