Digestive protease enzymatic approach

Overview Heterotrophs represent a major sink for primary production, and thus a critical part of the marine N cycle. In the pelagic realm, there have been attempts to estimate zooplankton grazing (both micro- and macro-zooplankton) using two major enzymatic approaches activities of digestive enzymes (especiaUy proteases in the case of N) (e.g., Gonzalez et al, 1993) and the activity of GDH, the... 

As mentioned above, the rectal route is very attractive for systemic delivery of peptide and protein drugs, but rectal administration of peptides often results in very low bioavailability due to not only poor membrane penetration characteristics (transport barrier) but also due to hydrolysis of peptides by digestive enzymes of the GI tract (enzymatic barrier). Of these two barriers, the latter is of greater importance for certain unstable small peptides, as these peptides, unless they have been degraded by various proteases, can be transported across the intestinal membrane. Therefore, the use of protease inhibitors is one of the most promising approaches to overcome the delivery problems of these peptides and proteins. Many compounds have been used as protease inhibitors for improving the stability of various peptides and proteins. These include aprotinin, trypsin inhibitors, bacitracin, puromycin, bestatin, and bile salts such as NaCC and are frequently used with absorption enhancers for improvement in rectal absorption. 

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