Intact Protein Analysis

The science of measuring proteins

Intact protein analysis is performed for a number of reasons, including determination of molecular mass (during top-down analysis) and posttranslational modification (PTM) (e.g., monoclonal antibody glycosylation). Full characterization of intact proteins is often performed on proteins that have been enriched or purified. These proteins can be introduced into the mass spectrometer (MS) by either direct infusion or through liquid chromatography (LC) coupled with electrospray ionization (ESI).

The primary advantage of direct infusion is that it allots more time for signal averaging. However, most intact protein mixtures require separation prior to introduction into the MS to reduce precursor spectral complexity and minimize ion suppression. This separation can be performed by either on- or off-line LC. High-resolution accurate mass (HRAM) analysis is also crucial for intact protein analysis.


Intact protein analysis solutions
Experience the highest resolution

Intact protein analysis relies on the ultra HRAM capacity of the Thermo Scientific Orbitrap Fusion Lumos Tribrid Mass Spectrometer. This system offers the highest resolving power of all Orbitrap-based instruments (up to 500,000 at m/z 200); likewise, its unique Advanced Vacuum Technology increases ion transmission and improves the quality of acquired intact protein mass spectra. Such advantages facilitate efficient enrichment of individual isobaric protein forms and subsequent top-down analysis.

Analyze large intact proteins

The Thermo Scientific Q Exactive HF Hybrid Quadrupole-Orbitrap Mass Spectrometer, with its optional Intact Protein Mode, enables high-resolution analysis of complex intact proteins and permits detailed characterization of larger and highly charged species such as entire antibodies and their individual light and heavy chains. With the additional resolving power of the Q Exactive HF MS, routine yet detailed characterization of proteins and biopharmaceuticals up to 50 kDa is possible.


Intact protein analysis workflow