Absolute quantification of human milk caseins and the whey/casein ratio during the first year of lactation

Whey proteins and caseins in breast milk provide bioactivities and also have different amino acid composition. Accurate determination of these two major protein classes provides a better understanding of human milk composition and function, and further aids in developing improved infant formulas based on bovine whey proteins and caseins. In this study, we implemented a LC-MS/MS quantitative analysis based on iBAQ label-free quantitation, to estimate absolute concentrations of α-casein, β-casein, and κ-casein in human milk samples (n = 88) collected between day 1 and day 360 postpartum. Total protein concentration ranged from 2.03 to 17.52 with a mean of 9.37 ± 3.65 g/L. Casein subunits ranged from 0.04 to 1.68 g/L (α-), 0.04 to 4.42 g/L (β-), and 0.10 to 1.72 g/L (α-), with β-casein having the highest average concentration among the three subunits. Calculated whey/casein ratio ranged from 45:55 to 97:3. Linear regression analyses show significant decreases in total protein, β-casein, κ-casein, total casein, and a significant increase of whey/casein ratio during the course of lactation. Our study presents a novel and accurate quantitative analysis of human milk casein content, demonstrating a lower casein content than earlier believed, which has implications for improved infants formulas

ABRF Proteome Informatics Research Group (iPRG) 2015 Study: Detection of Differentially Abundant Proteins in Label-Free Quantitative LC-MS/MS Experiments

Proteomic

Detecting a Tail Effect in Gravitational-Wave Experiments

Future gravitational-wave experiments looking at inspiralling compact binaries could achieve the detection of a very small effect of phase modulation induced by the tails of gravitational waves. Once a binary signal has been identified, further analysis of data will provide a measure of the total mass-energy M of the binary, which enters as a factor in this tail effect, by means of optimal signal processing. The detection of the effect will then consist in showing the compatibility of the measured values of M and of the other parameters depending on the two masses of the binary. This illustrates the high potentiality of gravitational-wave experiments for testing general relativity