Quantifying Biosynthesized Porphyrins and Complexes

Clemson University, Clemson SC

Investigators

Abstract

[unreadable] DESCRIPTION (provided by applicant): Concentration ratios of uroporphyrin isomers I and III, coproporphyrin isomers I-IV, and protoporphyrin IX biosynthesized in organisms are important indices in diagnosing inherited and induced porphyrias. The overall hypothesis guiding the proposed research is that fast, simple and inexpensive methodologies can be developed to quantify low-level concentrations of porphyrins and porphyrin-metal complexes found in organisms by improving photophysical (e.g., fluorescence, FL) and photochemical (e.g., chemiluminescence, CL) detection techniques. Specifically, we propose to develop methods to quantify the porphyrins above and their metal complexes using ion-pair high-performance liquid chromatography (HPLC) and a modified peroxyoxalate CL (PO-CL) detection approach based on the four complementary reaction pathways we have previously reported. With these systems, we predict that porphyrin detection limits will be two orders of magnitude lower than what is obtainable with current methodologies. The analytical systems devised to quantify porphyrins in this project are also expected to be applicable for detecting molecules of importance in a wide variety of medical research fields (e.g., allergies, diabetes, biomarkers). Using our newly developed methodologies, we will also determine binding constants of porphyrins with various metals based on the stoichiometric changes (e.g., quenching, enhancement) that occur in FL and CL processes. These results will indicate whether the tested metals directly affect metabolic processes involving porphyrins, such as the formation of heme. In addition, some nontoxic porphyrin-metal complexes having strong emission characteristics may prove useful as luminescent probes to increase contrast indices for the early detection of tumors. Ion-pair HPLC with CL detection will serve as a prototype for devising new equipment to diagnose porphyrias and provide early detection of tumors. The CL detection systems developed for ion-pair HPLC in this project will ultimately find use as powerful new detection systems for micro-chip, nano-chip, and microarray applications. [unreadable] [unreadable]