Polarization-modulation surface structures, determination

Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) is a surface-sensitive technique that can determine surface structures, chemical states of surface species, and their orientation relative to the surface [9,26]. The polarized parallel (p) component of the... 

Cholesterol, which is largely insoluble in aqueous m a, travels through the blood circulation in the form of Upoprotein complexes. The plasma lipoproteins are a family of globular particles that share common structural features. A core of hydrophobic lipid, principally triacylglycerols (triglycerides) and cholesterol esters, is surrounded by a hydrophilic monolayer of phospholipid and protein (the apolipoproteins) [1-3]. Lipid-apolipoprotein interactions, facihtated byi amphi-pathic protein helices that segregate polar from nonpolar surfaces [2,3], provide the mechanism by which cholesterol can circulate in a soluble form. In addition, the apolipoproteins modulate the activities of certain enzymes involved in Upoprotein metabolism and interact with specific cell surface receptors which take up Upopro-teins by receptor-mediated endocytosis. Differences in the Upid and apoUpoprotein compositions of plasma Upoproteins determine their target sites and classification based on buoyant density. 

Tertiary structure and model building A wire (coil and turn) cylinder ( polar properties of the surface. The folding is modulated so as to (i) favour Cys-Cys bond (ii) form antiparallel or parallel P> -sheet (iii) form a compact globular structure (iv) expose acidic amino acid residues where ever possible as pKa of the polypeptide is 5.2 (A). 

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