Discipline: Chemistry and Chemical Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Rebecca Vargas - California State University, Los Angeles
Co-Author(s): Ariga Bianca Yaghoobi, UC-Davis, CA
Antifreeze proteins (AFPs) are found in many organisms that need to survive in subfreezing environments including bacteria, fish, plants, and insects, where the latter organism exhibits the most active AFP activity. Despite the wide range of compositions and structures, it has been generally understood that AFPs function by interactions at the ice-water interface. These proteins are thought to bind to specific ice surfaces and inhibit ice crystal growth by changing the surface free energy. Previous studies have demonstrated the presence of transcripts of AFP genes in a summer desert beetle Microdera punctipennis, where its AFPs (MpAFPs) have a thermal protective function, suggesting a novel AFP protective mechanism. The widely studied AFPs from cold-adapted beetles include AFPs from Dendroides canadensis (DAFPs) found at high levels in the insect’s winter hemolymphs and have very similar tertiary structures to that of MpAFP. We hypothesize that DAFP-1 will exhibit similar thermal protective behaviors to MpAFPs. This hypothesis is being tested by preserving the enzymatic activity of lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH). DAFP-1 is purified and isolated using our previously published procedures. Standard enzymatic assays are performed on the model LDH and ADH, before and after thermal treatments at different temperatures (40, 50, and 60 °C) as well as in the presence of DAFP-1. Data has suggested that DAFP-1 is able to protect LDH at 40, 45 and 50 °C at a range of 30μg/ml to 60 μg/ml for a short period of time. Additionally, preliminary data suggests that the protective behavior of DAPF-1 is comparable to that of a known common enzyme protectant, Trehalose. At 700 μg/ml of trehalose some thermal protection can be observed after a certain period of time. Compared to DAFP-1, it is a worse thermal protectant over time as well as in quantity. The amounts of trehalose used are over tenfold compared to DAFP-1 and an improvement of protection is not observed. Other preliminary data suggest that ADH shares a similar trend to LDH in terms on how well it is protected via DAFP-1. The molecular mechanism behind how DAFP-1 protects these model enzymes is not fully understood and is currently being investigated. Understanding the novel properties and mechanisms behind AFPs could lead not only to understanding how insects are able to survive during extreme weather but to expand the potential applications of AFPs in industrial fields. This specific novel function of DAFP-1 could be exploited further for use towards health related issues or for the delivery of protein based drugs.
Funder Acknowledgement(s): The funding for the CSULA LSAMP-BD Cohort XI program is provided by the National Science Foundation under Grant # HRD-1463889.
Faculty Advisor: Xin Wen, firstname.lastname@example.org
Role: I performed all of these assays at the different time course. I optimized the conditions of the assay protocol and concentrations needed for this system to be successful. I purified the AFP necessary for this project.