Document Type

Thesis

Degree

Master of Science (MS)

Major/Program

Chemistry

First Advisor's Name

Jaroslava Miksovska

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

David C. Chatfield

Third Advisor's Name

Xiaotang Wang

Date of Defense

7-8-2010

Abstract

The Ca2+ association to calcium binding proteins (CaBPs) represents an essential step in Ca2+ signal transduction. This study presents a characterization of Ca interactions with two CaBPs, calmodulin and DREAM, using time-resolved photothermal and fluorescence techniques. Calcium binding to the calmodulin C-terminal domain is associated with a volume change of 40 mL mol-1and an enthalpy change of 35 ± 16 kcal mol-1. These parameters are consistent with the Ca2+ triggered exposure of hydrophobic patches on the calmodulin surface. Also, the rate limiting step for Ca2+ binding to calmodulin is the closed-to-open transition of the C-terminal domain that occurs with a lifetime of 400 μs. Unlike calmodulin, DREAM exists in a dynamic equilibrium of two conformations and Ca2+ binding shifts the equilibrium towards a more compact conformation. These data clearly demonstrate that conformational dynamics play a crucial role in the transmission of Ca2+ signals.

Identifier

FI14062264

Comments

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