UC San Diego

Meeting the nutritional demand for high‐risk infants is challenging and problems such as necrotizing enterocolitis, growth faltering, and neurodevelopmental impairment persist inneonatal intensive care. The use of pasteurized donor human milk is increasing for high‐risk infants particularly when mother’s milk is insufficient, or breastfeeding is not possible. Proteins are a major source of nutrients in milk and are degraded into peptides and subsequently into nutritious amino acids by proteases. Proteomics studies have identified at least 38 different proteases in human milk, but little research has been performed to biochemically characterize these enzymes. We utilized our mass spectrometry-based peptide digestion assay to detect and characterize the active proteases in human milk. We first acidified the milk to