Effects of ligand environment of the binding strength and selectivity of a calcium chelator

Cindy Tung Chau
California State University, Los Angeles

Calcium ions, which are second messengers, are released inside certain cells in an oscillatory signal. This signal is associated with a variety of important physiological processes such as hormone secretion. To study their effects on cells and proteins, a molecule that will mimic these oscillations has been designed. An unsubstituted bis-spiropyran is known to be photochromic. Addition of substituted amines (R1=H; R2=CH2CO2-) creates a binding site for Ca2+, which should reversibly be disrupted upon irradiation. Compound (1), R1=CH3; R2=CH2CO2-, was found to bind Ca2+ moderately and selectively over Mg2+, and is not photochromic. To examine the effects of changing R2 on binding strength and selectivity, compound (1), R1= CH3; R2= CH2CH2CO2-, will be synthesized. The results of binding M2+ ions to this chelator will be presented.

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