Spectroscopy Analysis The Influence Of Secondary Structure Of β-casein In Human Milk On The Structure Of Milk Fat Globule Membrane

Human milk is the best food in the baby growth process, the β-casein can provide the most suitable for the baby’s rapid growth of amino acids, calcium, phosphorus, etc., Which is the most suitable for baby small intestinal digestion and absorption of protein, and milk fat globule membrane can embed the milk fat globule, which is beneficial to the newborn’s transport of nutrients. Therefore, study the structure of (3-casein and milk fat globule membrane are particularly important, in order to understand the β-casein advanced structure, the basic research is to determine and analysis the secondary structure, at the same time, observation of the structure of milk fat globule membrane and explore the influence of the structure of β-casein in milk fat globule membrane formation is of great significance for the embedding the milk fat and guiding the scientific feeding of infants and young children.This paper takes the Chinese milk as research object, through separation and purification, using Circular Dichroism spectra and Raman spectra to research the secondary structure of β-casein in human milk, at the same time, studied the effect of different pH on the secondary structure, and compared the results of secondary structure with secondary structure prediction results. We also analyses the particle size of milk fat globule, and used the physical method to separation the milk fat globule membrane. We also used the laser confocal scanning microscope (CLSM) and SDS-PAGE to observation and identification of the structure formation of the (3-casein in milk fat globule membrane. The main research conclusions are as follows:(1). Under the different pH conditions, the secondary structure of human milk (3-casein in Circular Dichroism method indicated:the random coil was49%～51%, β-turn was30%～34%, β-sheet was16%～18%, α-helix was0.5%～2%. The high content of α-helix was in pH8, and the content of random coil, reached the maximum at pH10.(2). Under the different pH conditions, the secondary structure of human milk P-casein in Raman spectroscopy method indicated:the random coil was45%～79%, β-turn was10%-40%, β-sheet was7%～23%, α-helix was2%-9%. The tyrosine residues of p-casein tended to be "expose", which was high at pH7, and low at pH10. Two spectrometry methods of results are basically identical with the predicted results.(3). Separation the milk fat globule membrane was using the physical method. By the method of SDS-PAGE to identify the formation process of the artificial adding β-casein in milk fat globule membrane. The results showed that the adding β-casein participated the process in form the milk fat globule membrane, and with the increased of adding amount of protein, forming membrane protein content increase.(4). The fat globule membrane was observed by CLSM, observed the process of crushing and gathering of fat globule membrane. The results further identified the β-casein participated the process in form the milk fat globule membrane.