Premium
Mass spectrometric study of gas‐phase ions of acid β‐glucosidase (Cerezyme) and iminosugar pharmacological chaperones
Author(s) -
Rajabi Khadijeh
Publication year - 2014
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.3412
Subject(s) - chemistry , ion , non covalent interactions , molecule , covalent bond , mass spectrometry , chaperone (clinical) , enzyme , gas phase , glycoprotein , calnexin , crystallography , stereochemistry , biophysics , biochemistry , chromatography , organic chemistry , hydrogen bond , endoplasmic reticulum , calreticulin , biology , medicine , pathology
The effect on the conformations and stability of gas‐phase ions of Cerezyme, a glycoprotein, when bound to three small‐molecule chaperones has been studied using intact ESI MS, collision cross section and MS/MS measurements. To distinguish between the peaks from apo and small‐molecule complex ions, Cerezyme is deglycosylated (dg‐Cer). ESI MS of dg‐Cer reveals that glycosylation accounts for 8.5% of the molecular weight. When excess chaperone, either covalent (2FGF) or noncovalent (A and B iminosugars), is added to solutions of dg‐Cer, mass spectra show peaks from 1:1 chaperone–enzyme complexes as well as free enzyme. On average, ions of the apoenzyme have 1.6 times higher cross sections when activated in the source region of the mass spectrometer. For a given charge state, ions of complexes of 2FGF and B have about 30% and 8.4% lower cross sections, respectively, compared to the apoenzyme. Thus, binding the chaperones causes the gas‐phase protein to adopt more compact conformations. The noncovalent complex ions dissociate by the loss of charged chaperones. In the gas phase, the relative stability of dg‐Cer with B is higher than that with the A, whereas in solution A binds enzyme more strongly than B. Nevertheless, the disagreement is explained based on the greater number of contacts between the B and dg‐Cer than the A and dg‐Cer (13 vs. 8), indicating the importance of noncovalent interactions within the protein–chaperone complex in the absence of solvent. Findings in this work suggest a hypothesis towards predicting a consistent correlation between gas‐phase properties to solution binding properties. Copyright © 2014 John Wiley & Sons, Ltd.