## Dissertations from ProQuest

#### Title

Magnetic resonance and molecular mechanics studies of lariat ethers and calcium-binding proteins

1990

Article

#### Degree Name

Doctor of Philosophy (Ph.D.)

Chemistry

#### First Committee Member

Luis A. Echegoyen, Committee Chair

#### Abstract

Part I. A combination of spin-lattice relaxation measurements and molecular mechanics calculations demonstrated that bibracchial lariat ethers which were synthesized as open cryptand- analogues, undergoes compression and desolvation upon complexation showing a "cryptand-like" behavior in solution as well as in the solid state. This "cryptand-like" behavior of lariat ethers in solution proved to be a solvent-dependent property. Also, it was demonstrated that a charge can induce rigidity to mono-aza and diaza lariat ethers upon complexation depending upon their structure.Molecular Mechanics calculations proved to be a useful tool to explain and to better understand the complexation behavior of lariat ethers with different molecular architectures. Also, conformational preferences of lariat ethers were rationalized using molecular mechanics calculations.Part II. ESR studies, using vanadyl as a probe, were performed in order to obtain information about calcineurin and $\alpha$-lactalbumin metal binding sites. Calcineurin, (which is composed of two subunits: A and B), as well as its B-subunit has vanadyl binding sites. Since calcineurin showed at least two different binding sites, it was also concluded that vanadyl binds to calcineurin A-subunit. Competition experiments showed that vanadyl has a higher affinity for calcineurin compared to calcium.$\alpha$-Lactalbumin binds to vanadyl in a 1:2 (protein:vanadyl) ratio with only one kind of vanadyl binding site. Competition experiments showed that calcium has a higher affinity for a-lactalbumin compared to vanadyl.

#### Keywords

Chemistry, Physical