Gülfen Mustafa, Özdemir Abdil, Lin Jung-Lee, Chen Chung-Hsuan
Department of Chemistry, Faculty of Arts and Sciences, Sakarya University, 54187, Sakarya, Turkey.
Genomics Research Center, Academia Sinica, Taipei, Taiwan.
Rapid Commun Mass Spectrom. 2016 Oct 15;30(19):2171-82. doi: 10.1002/rcm.7683.
Insulin is a peptide hormone secreted by pancreatic β-cells. Ca(II) and Mg(II) ions play an important role in the secretion of insulin. There is no study about a direct complexation of Ca(II) or Mg(II) with insulin and their equilibrium constants. Electrospray ionization mass spectrometry (ESI-MS) is a practical method for the monitoring of non-covalent complexes such as Ca(II)-insulin and Mg(II)-insulin. Here, the equilibrium constants of Ca(II)-insulin and Mg(II)-insulin non-covalent complexes have been calculated after ESI-MS measurements in aqueous solutions.
The effects of pH, competitive binding, ion exchange, and Na(I) and K(I) ions on Ca(II)-insulin and Mg(II)-insulin complexation have been examined by measuring by ESI-MS. The dissociation equilibrium constants (K1 and K2 ) of Ca(II)-insulin and Mg(II)-insulin complexes were calculated from the binomial graph derived from the ESI-MS normalized peak intensities. The MS/MS spectra of the complexes have been examined.
The dissociation equilibrium constants were found to K1 : 1.29 × 10(-4) M and K2 : 9.69 × 10(-4) M for the Ca(II)-insulin complexes, and K1 : 1.37 × 10(-4) M and K2 : 9.12 × 10(-4) M for Mg(II)-insulin complexes. Ca(II) ions have higher complexation capability with insulin than Mg(II) ions.
The binding equilibrium constants of Ca(II)- and Mg(II)-insulin non-covalent complexes have been determined successfully by ESI-MS. Ca(II) and Mg(II) ions are involved in the insulin secretion by forming non-covalent complexes. Copyright © 2016 John Wiley & Sons, Ltd.
胰岛素是一种由胰腺β细胞分泌的肽类激素。钙（II）和镁（II）离子在胰岛素分泌中起重要作用。目前尚无关于钙（II）或镁（II）与胰岛素直接络合及其平衡常数的研究。电喷雾电离质谱（ESI-MS）是监测诸如钙（II）-胰岛素和镁（II）-胰岛素等非共价复合物的实用方法。在此，通过在水溶液中进行ESI-MS测量后计算出了钙（II）-胰岛素和镁（II）-胰岛素非共价复合物的平衡常数。
通过ESI-MS测量研究了pH值、竞争性结合、离子交换以及钠（I）和钾（I）离子对钙（II）-胰岛素和镁（II）-胰岛素络合的影响。从ESI-MS归一化峰强度得出的二项式图计算出钙（II）-胰岛素和镁（II）-胰岛素复合物的解离平衡常数（K1和K2）。对复合物的MS/MS光谱进行了研究。
发现钙（II）-胰岛素复合物的解离平衡常数为K1：1.29×10⁻⁴ M和K2：9.69×10⁻⁴ M，镁（II）-胰岛素复合物的解离平衡常数为K1：1.37×10⁻⁴ M和K2：9.12×10⁻⁴ M。钙（II）离子与胰岛素的络合能力高于镁（II）离子。
通过ESI-MS成功测定了钙（II）-和镁（II）-胰岛素非共价复合物的结合平衡常数。钙（II）和镁（II）离子通过形成非共价复合物参与胰岛素分泌。版权所有© 2016约翰威立父子有限公司。
