Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (04): 971-977.doi: 10.3866/PKU.WHXB201112201

• BIOPHYSICAL CHEMISTRY • Previous Articles     Next Articles

Effect of Alkali Metal Ions on the Dissociation of Glycine Pentapeptide in the Gas Phase

WANG Qing1, CHU Yan-Qiu1, ZHANG Kai1, DAI Xin-Hua2, FANG Xiang2, DING Chuan-Fan1   

  1. 1. Institute of Laser Chemistry, Department of Chemistry, Fudan University, Shanghai 200433, P. R. China;
    2. Chemical Metrology & Analytical Science Division, National Institute of Metrology, Beijing 100013, P. R. China
  • Received:2011-11-03 Revised:2011-12-12 Published:2012-03-21
  • Contact: DING Chuan-Fan
  • Supported by:

    The project was supported by the National Science & Technology Pillar Program, China (2009BAK60B03) and National Major Scientific Instrument and Equipment Development Project, China (2011YQ09005).

Abstract: To obtain more structural information of polypeptides, glycine pentapeptide (simplified as GGGGG or G5) was chosen as a model to investigate the impact of alkali metal ions on the dissociation of GGGGG in the gas phase. Stoichiometric G5 and alkali metal salt solutions, including Li + , Na+ , K+ , Rb+ , were mixed, respectively, and then the solutions were left to stand at room temperature for 10 h to reach equilibrium. The mass spectrometric results indicated that the alkali metal ions and G5 could form 1:1 or 2: 1 non-covalent complexes in solution. The energy of the collision induced dissociation (CID) was 25 eV. The gas phase CID results demonstrate that in the 1:1 complexes, the extent of fragmentation decreases according to the order: Li+, Na+, K+, Rb+. Moreover, the unusual c, z ions were observed in the Rb+ complex. In the 2:1 non-covalent complexes, the extent of fragmentation increases according to the order: Li+ , Na+ , K+, Rb+. The gas phase dissociation of the Na+, K+, Rb+ 2:1 complexes are easier than their 1:1 complexes. Except for Li + , the activation abilities of the double metal ions to G5 are stronger than that of the single metal ion to G5, which can induce more dissection sites in the glycine pentapeptide and lead to the formation of more kinds of fragment ions.

Key words: Mass spectrometry, Collision-induced dissociation, Alkali metal ion, Pentapeptide, Gas phase dissociation