Table 2 Composition of the free (transport) lipoproteins in plasma of human

Fractions	Source	nM	Densi ty	Composition
				Pro teins	Total lipid	Percentages of total lipids (100%)
(%)	(%)	TAG	PHL	CHE	CHF	FFA
CHM	Intes tine	< 1000	< 0.96							-
VLDL	Liver	< 90	< 0.01							-
LDL	CHM Liver	< 30	< 1.06							-
HDL	Liver, intes Tine, CHM, VLDL	< 20	< 1.20
Albu min+ FFA	Adipo se tissue	< 5	> 1.30			-	-	-	-

Inside the molecule lipoproteins have the nucleus with lipids such as triglycerides and free cholesrerol. Surrounding this inner core of neutral lipids are located esters of cholesterol, phospholipids and proteins.

In structural lipoproteins which for example composed the cell membranes hydrophilic part is inside of membranes and hydrophobic - outside.

Glycoproteins – specimens, structures, properties, roles

GP (glycos – sweet) have restrictively been defined as conjugated proteins that contain, as a prosthetic group, one or more saccharides lacking a serial repeat unit and bound covalently to a peptide chain (D-galactose, D-mannose, D-glucose, L-fucose, N-acetylglycosamine, N-acetylgalactose, sialic acid, arabinose, neuraminic acid, xylose). Connection between protein and prosthetic group is covalent, carbohydrates-peptides one. Carbohydrates covalently linked to glycoproteins by glycosyl bonds. Covalent linkage of sugars to the peptide chain is a central part of glycoprotein structure, and only a limited number of bond types are found. The carbohydrate attached at one or at multiple points along a polypeptide chain usually contains less than 12-15 sugar residues. In some cases the carbohydrate component consists of a single sugar moiety, as in the sub maxillary gland glycoprotein (single N-acetyl-a-D-galactosaminyl residue) and in some types of mammalian collagens (single a-D-galactosyl residue). In general, glycoproteins contain sugar residues in the D form, except for L-fucose, L- arabinose, and L-iduronic acid; A glycoprotein from different animal species often has an identical primary structure in the protein component, but a variable carbohydrate component. This heterogeneity of a given protein may even be true within a single organism. For example, pancreatic ribonuclease A and В forms have identical amino acid sequences and a similar kinetic specificity toward substrates but differ significantly in their carbohydrate compositions.

<== попередня сторінка	\|	наступна сторінка ==>
Phosphoproteins	\|	Properties of GP

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