Fig. 2.

Free radical generation under hypobaric hypoxic stress resultant into protein modification and the amino acid oxidation in skeletal muscle tissue homogenate by fluorescence excitation-emission spectra. a Protein carbonylation. b Advanced oxidation protein products (AOPPs). c Formation of protein-protein cross-linkage (bityrosine formation) due to presence of free radical species shows characteristic emission spectra at 380–440 nm. d Emission spectra due to the oxidation of aromatic amino acid tryptophan under hypoxic condition, showing a shift in intensity at the peak emission wavelength. e Excitation spectra of lysine conjugates measured at 325–380 nm. f Emission spectra at 425–480 nm for the lysine conjugates with lipid peroxidation products like malondialdehyde, 4-hydroxynenal through covalent attachment designated as reactive carbonyl species (RCS)-derived protein carbonylation. Data represents the mean ± SE; N = 5. Different symbols, double dagger, asterisk, and dagger indicate the significant differences between experimental groups (p < 0.05), while groups with matching symbols denote no difference (p ≥ 0.05)