Mechanistic Investigation And Potential Application Of A Fatty Acid Decarboxylating Cytochrome P450 Peroxygenase

OleT (CYP152L1) is a recently discovered cytochrome P450 that is structurally similar to peroxide dependent P450s that catalyze fatty acid hydroxylations. OleT has been shown to catalyze the cleavage of n chain length fatty acids to form n-1 alkenes through C-C bond scission of the terminal carboxylate. Using headspace GC-MS and FTIR with isotopically labeled substrates, we have confirmed that OleT metabolizes eicosanoic acid to 1-nonadecene, forming carbon dioxide (CO2) as a co-product of the reaction. No oxygen deriving from peroxide is observed in either product. In order to probe the mechanistic deviation of OleT from P450 peroxygenases, we have employed a “decoy” approach where a short chain length fatty acid provides the acidic group necessary for peroxide heterolysis, and also allows access of small molecule probe substrates. Using this approach, we confirm that OleT also catalyzes epoxidation and hydroxylation reactions. Products derived from the metabolism of radical clock substrates directly show that OleT is capable of efficient oxygen rebound with radical lifetimes that are similar to other P450 monooxygenases. A site-directed mutant, in which the acidic group is instead provided by the protein framework, circumvents the need for a substrate carboxylate, and shows efficient metabolism of a wide range of hydrocarbon substrates. In addition, we described efforts to leverage OleT for electron driven hydrocarbon production, replacing H2O2 with a non-conventional redox partner or a Ru(II) photosensitizer covalently attached to a non-native surface cysteine.Last but not least, the development of a general and facile colorimetric optical assay for the detection of carbondioxide (CO2) generated from enzymatic reactions is described. The assay utilize the use of natural abundant of carbonic anhydrases, and a readily available pH indicator (ex. bromothymol blue) for the monitoring of pH changes induced by the release of CO2 using a standard UV-vis spectrophotometer. This optical method can accurately and reliably quantify CO2 produced from two entirely different class of enzymes: α-ketoglutarate-dependent dioxygenases and cytochrome P450 OleT decarboxylase

An Administrative Model for a Bilingual Education Program for Middle-Level Students in Taiwan

The purpose of this project was to develop an administrative model for a bilingual education program for middle-level students in Taiwan. To accomplish this purpose, a review of related literature was conducted. Additionally, selected materials were obtained adapted for use

Biodiversity shapes tree species aggregations in tropical forests

Spatial patterns of conspecific trees are considered as the consequences of biological interactions and environmental influences. They also reflect species interactions in plant communities. However, biological attributes are often neglected while deliberating the factors shaping species distributions. As rising attentions are paid to spatial patterns of tropical forest trees, we noticed that seven Center of Tropical Forest Sites and four Forest Dynamic Plots in Asia and America have presented analogously high proportions of species with aggregated conspecific individuals coincidently. This phenomenon is distinctive and repudiates fundamental ecology hypotheses which suggested dispersed distributions of conspecific tropical trees due to intensive density and natural enemy pressures in tropical forests. We believe that similar aggregation patterns shared by these tropical forests implies the existence of structuring forces in biogeographical scale instead of habitat heterogeneity in local community scales as scientists have considered. To approach the factors contributing to this cross-continent spatial pattern of trees, we obtained and reviewed ecosystem attributes, including topography, temperature, precipitation, biodiversity, density, and biomass, of these forests. Here we show that the proportions of aggregated species are actually constants independent of any ecosystem attributes regardless the nature of these tropical forests. However, local biodiversity are the major factor determining the number of aggregated species and the aggregation of large individuals of these forests. Aggregation of large trees declines along rising biodiversity, while the numbers of aggregated species increase permanently along lifting biodiversity. We propose a possible equilibrium and saturated status of the tropical forests in accommodating aggregated species. Furthermore, the tight correlations of biodiversity and species aggregation strongly imply the importance of overlooked biological interactions in shaping the spatial patterns in the tropical forests