Date of Award


Degree Name

Master of Science




Chuan Xiao


Many living organisms have biological clocks known as circadian rhythms that control various physiological and behavioral processes, tailored with the day and night. At the cellular level, the circadian clock drives daily rhythms with a transcriptional-translational feedback loop (TTFL) established by multiple transcription factors and genes under their regulation. Circadian Locomotor Output Cycles Kaput (CLOCK) and Brain and Muscle ARNT-like protein 1 (BMAL1) are two of those transcription factors, initiating the TTFL by forming a heterodimeric complex that bind to DNA promoters. Neuronal PAS domain protein 2 (NPAS2) is a functional analog to CLOCK. Less knowledge about NPAS2, in contrast to CLOCK, is available, hindering our understanding of its roles in the circadian rhythm. To study human NPAS2, large amounts of recombinant protein were expressed in bacterial systems and purified using various liquid chromatography techniques. Dynamic light scattering, circular dichroism, and size-exclusion chromatography were used to characterize the recombinant human NPAS2. Abnormal rhythms attributed to NPAS2 have been associated with mental illnesses and certain types of cancer. The characterization of NPAS2 will deepen our understanding of its functions in the circadian rhythm and will facilitate the design of therapeutic treatments targeting circadian related disorders.




Received from ProQuest

File Size

40 pages

File Format


Rights Holder

Brenda Moreno