Characterization of Dipeptidyl Peptidase IV Enzyme Activity in Serum of the Komodo Dragon (Varanus komodoensis)

Abstract

Aims: Soluble serum dipeptidyl peptidase IV (DPPIV) is a protease that cleaves dipeptides from proteins that have alanine or proline next to the N-terminal amino acid. This enzyme demonstrates substantial immune function by regulating T-lymphocyte activity, T-cell chemotaxis, growth, and proliferation during an inflammatory response. The goal of this study was to characterize DPPIV activity in the serum of the Komodo dragon (Varanus komodoensis). Study design: Place and Duration of Study: Serum was collected from eight Komodo dragons at the San Antonio Zoo (n = 5) and Houston Zoo (n = 3) in June of 2012. The samples were analyzed for DPPIV enzyme activity in the Department of Chemistry at McNeese State University in Lake Charles, Louisiana, USA Methodology: We used Ala-Pro-AFC, a dipeptide conjugated to a fluorescent probe via an amide linkage, to measure the activity of DPPIV in the serum of Komodo dragons (Varanus komodoensis). The fluorescent intensity of the product formed was measured at excitation and emission wavelengths of 395 and 530 nm, respectively, in a fluorimeter. Results: Incubation of different volumes of serum from the Komodo dragon with Ala-Pro-AFC resulted in a volume-dependent increase in fluorescent intensity, which was decreased in a concentration-dependent manner by diprotin A, a specific inhibitor of DPPIV activity. Kinetic analysis showed that the DPPIV enzyme activity was detectable after five minutes, and that was nearly linear for three hours. A thermal profile showed that Komodo dragon DPPIV exhibited dramatically reduced activities at low temperatures (5-10 o C), but activity increased linearly with temperature and was maximal at the highest temperature tested (40 o C). Conclusion: These results from this study indicate that Komodo dragons exhibit considerably high serum DPPIV activities, which are likely to contribute to T-cell activation and function, and act as a bridge between innate and adaptive immunity in these ancient vertebrates.

Characterization of Phospholipase A2 Enzyme Activity in Serum of the Komodo Dragon (Varanus komodoensis)Soluble phospholipase A2 (sPLA2) is an enzyme found in the peripheral circulation of vertebrates which has significant immunological activity. This en

“…[23] showed that the preferred body temperature of Komodo dragons is 34.0-35.6 o C, and thus these animals have a relatively high PLA2 activity (111.1 -114.3 nmol/30 min) in this temperature range. The PLA2 thermal profile presented in Figure 3 exhibits different characteristics than the temperature dependent serum complement activity reported by Merchant et al [12], but was almost identical to the dipeptidyl peptidase IV activity [13]. These data would seem to indicate that an innate immune response in Komodo dragons would be optimal at 35-40 o C. It would be reasonable to expect that these animals would need optimal immune activity during warmer weather when they are more active, and might be more likely to engage in territorial disputes.…”

“…Several recent studies have characterized antibacterial activity [11], serum complement [12], and dipeptidyl peptidase [13] activities of serum from the Komodo dragon. In addition, these animals have been reported to express antimicrobial peptides [14].…”

Characterization of plasma secretory phospholipase A2 activity in the prairie rattlesnake (Crotalus viridis)

“…Members of the families Alligatoridae (Merchant et al, 2009;Siroski et al, 2013) and Crocodylidae (Merchant et al, 2011;Merchant et al, 2017) express high levels of circulating secretory PLA 2 enzymes. In addition, Komodo dragons (Varanus komodoensis, Merchant et al, 2018) and several species of turtles (Merchant, unpublished results) also exhibit relatively high circulating levels of this enzyme. This study was conducted to identify and characterize PLA 2 activity in the plasma of the prairie rattlesnake (Crotalus viridis).…”