Date of Award

5-14-2010

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Chemistry

Department

Chemistry

Major Professor

Jursic, Branko S.; Cai, Yang

Second Advisor

Cutler, Jim E.

Third Advisor

Rick, Steven W.

Fourth Advisor

Gibb, Bruce C.

Abstract

Candida albicans is an opportunistic fungal pathogen that may cause mucutaneous infection and/or disseminated candidasis if the host defense system is impaired (such as those in HIV patients). Cell surface of C. albicans is the frontier where initial interplay between host-pathogen takes place and therefore is of great importance in understanding the mechanism of hostpathogen interaction. MALDI-TOF-MS analysis of intact fungal cells yielded mass signatures for rapid species differentiation, strain grouping and yeast morphogenesis monitoring. Cell surface biotinylations at low temperature (4°C), enzymatic digestion of the intact fungal cell surface proteins ("whole cell shaving"), biotin-avidin affinity enrichment of biotinylated peptides, liquid chromatography mass spectrometry (LC-MS) based proteomic approach were employed for unambiguous identification of cell wall/cell wall associated proteins and the exposed peptide segments of these proteins. SILAC (Stable Isotope Labeling by Amino acids in Cell Culture) based CWP quantification analyses were performed to monitor CWP accumulation level change in response to hyphae induction. Information on surface exposed peptide segments and regulation of cell wall/surface protein during morphogenesis provided new candidates to the pool of potential peptide targets for protective vaccine development. A New type of "fluorous" (fluorinated alkane) affinity gained popularity due to its low level nonspecific protein/peptide binding. Fluorous labeling reagents that target primary amine groups in proteins/peptides were synthesized and characterized. The acid labile linker in the labeling reagents allows cleavage of the bulky fluorous tag moiety and the long oligo ethylene glycol (OEG) spacer after fluorous affinity purification. Upon collision induced decomposition, the labeled peptide ion yielded a characteristic fragment that could be retrieved from the residual portion of fluorous affinity tag, and serve as a marker to indicate that the relevant peptide had been successfully labeled. Results showed that both the protein/peptide labeling and affinity enrichment/separation process were highly efficient.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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