Localized changes in the structural stability of myoglobin upon adsorption onto silica particles, as studied with hydrogen/deuterium exchange mass spectrometry.
A new method is presented for monitoring the conformational stability of various parts of a protein that is physically adsorbed onto nanometer-sized silica particles. The method employs hydrogen/deuterium (H/D) exchange of amide hydrogens, a process that is extremely sensitive to structural features of proteins. The resulting mass increase is analyzed with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Higher structural specificity is obtained by enzymatically cleaving the adsorbed proteins prior to mass spectrometric analysis. The mass increases of four peptic fragments of myoglobin are followed as a function of the H/D exchange time. The four peptic fragments cover 90% of the myoglobin structure. Two of the peptic fragments, located in the middle of the myoglobin sequence and close to the heme group, do not show any adsorption-induced changes in their structural stability, whereas the more stable C- and N-terminal fragments are destabilized. Interestingly, for the N-terminal fragment, comprising residues 1-29, two distinct and equally large conformational populations are observed. One of these populations has a stability similar to that in solution (-23 kJ/mol), whereas the other population is highly destabilized upon adsorption (-11 kJ/mol).
Buijs
Jos
J
Division of Ion Physics, Angström Laboratory, Uppsala University, Box 534, 75121, Uppsala, Sweden. jos.buijs@biacore.com
Ramström
Margareta
M
Danfelter
Mikael
M
Larsericsdotter
Helén
H
Håkansson
Per
P
Oscarsson
Sven
S
D000327:Adsorption; D000818:Animals; D003903:Deuterium / Q000737:chemistry*; D005583:Fourier Analysis; D005753:Gastric Mucosa / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry*; D007700:Kinetics; D013058:Mass Spectrometry / Q000379:methods; D015233:Models, Statistical; D009092:Mucous Membrane / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry*; D010434:Pepsin A / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012756:Sheep; D012825:Silicon / Q000737:chemistry; D013552:Swine; D013997:Time Factors
D009211:Myoglobin; D010455:Peptides; D006859:Hydrogen; D003903:Deuterium; D010434:Pepsin A; D012825:Silicon