Sialylation Shields Glycoproteins from Oxidative Stress: Mechanistic Insights into Sialic Acid Oxidation and Structural Stability

• DOI: 10.1021/jacs.4c14454
• Publication Date: 2025-02-05T18:15:46Z
• Authors: Yamei Wang; Dongbei Jin; Lifang Ren; Ning Wang; Yifei Jia; Zhen Zheng; Wensheng Cai; Haohao Fu; Gongyu Li

Sialylation, a crucial yet labile protein modification, is increasingly recognized for its role in modulating structure, function, and stability. While the impact of oxidative stress on integrity well-established, protective sialylation against such damage remains poorly understood. This study employs microscale low-temperature plasma device to generate controlled, deep radical oxidation environment mimicking cellular stress. By subjecting free sialic acids (Neu5Ac Neu5Gc) time-resolved exposure, high-resolution mass spectrometry, high-fidelity density functional theory calculations, we establish an unprecedented pathway, revealing unique stepwise side chain prior ring opening. Comprehensive maps comprising over 100 intermediates provide molecular basis higher propensity Neu5Gc Neu5Ac resisting oxidation. Further, using human transferrin as model glycoprotein, demonstrate unfolding. Through combination site mapping, enzymatic treatments, all-ion unfolding ion mobility-mass identify specific patterns structural motifs that are maintaining stability under Our findings insights into intricate interplay between stress, highlighting importance stabilizing conformations various stresses.