Comprehensive characterization and proteoform analysis of the hydrophobic surfactant proteins B and C in calf pulmonary surfactant

Validation of a high-performance liquid chromatography method for determining lysophosphatidylcholine content in bovine pulmonary surfactant medication

Pulmonary surfactant replacement therapy is a promising improvement in neonatal care for infants with respiratory distress syndrome. Lysophosphatidylcholine (LPC) is an undesirable component that can hinder surfactant proteins from enhancing the adsorption of surfactant lipids to balance surface tensions by creating a saturated coating on the interior of the lungs. A novel normal-phase liquid chromatography method utilizing UV detection and non-toxic solvents was developed and validated for the first time to analyze LPC in the complex matrix of pulmonary surfactant medication. The analytical method validation included evaluation of system suitability, repeatability, intermediate precision, linearity, accuracy, limit of detection (LOD), limit of quantification (LOQ), stability and robustness. The method yielded detection and quantification limits of 4.4 and 14.5 μg/ml, respectively. The calibration curve was modified linearly within the LOQ to 1.44 mg/ml range, with a determination coefficient of 0.9999 for standards and 0.9997 for sample solutions. Given the lack of reliable published data on LPC analysis in pulmonary surfactant medications, this newly developed method demonstrates promising results and offers advantages of HPLC methodology, including simplicity, accuracy, specificity, sensitivity and an exceptionally low LOD and LOQ. These attributes contribute to considering this achievement as an innovative method.

Protein Palmitoylation in Bovine Ovarian Follicle

Protein palmitoylation is a reversible post-translational modification by fatty acids (FA), mainly a palmitate (C16:0). Palmitoylation allows protein shuttling between the plasma membrane and cytosol to regulate protein stability, sorting and signaling activity and its deficiency leads to diseases. We aimed to characterize the palmitoyl-proteome of ovarian follicular cells and molecular machinery regulating protein palmitoylation within the follicle. For the first time, 84 palmitoylated proteins were identified from bovine granulosa cells (GC), cumulus cells (CC) and oocytes by acyl-biotin exchange proteomics. Of these, 32 were transmembrane proteins and 27 proteins were detected in bovine follicular fluid extracellular vesicles (ffEVs). Expression of palmitoylation and depalmitoylation enzymes as palmitoyltransferases (ZDHHCs), acylthioesterases (LYPLA1 and LYPLA2) and palmitoylthioesterases (PPT1 and PPT2) were analysed using transcriptome and proteome data in oocytes, CC and GC. By immunofluorescence, ZDHHC16, PPT1, PPT2 and LYPLA2 proteins were localized in GC, CC and oocyte. In oocyte and CC, abundance of palmitoylation-related enzymes significantly varied during oocyte maturation. These variations and the involvement of identified palmitoyl-proteins in oxidation-reduction processes, energy metabolism, protein localization, vesicle-mediated transport, response to stress, G-protein mediated and other signaling pathways suggests that protein palmitoylation may play important roles in oocyte maturation and ffEV-mediated communications within the follicle.