Isolation and characterization of glycosaminoglycans in human plasma.

Abstract

We have described methodology for the isolation and quantitation of glycosaminoglycans present in human plasma. Plasma glycosaminoglycans can be quantitatively adsorbed on a DEAESephacel ion exchanger and eluted with a salt gradient as two groups: a low-charge fraction and a high-charge fraction. The low-charge fraction consists of chondroitin sulfate with a low sulfate content and the high-charge fraction consists of heparan sulfate, chondroitin sulfate, and keratan sulfate (type I). We have determined the plasma concentration of each of these glycosaminoglycans in six normal human subjects.We have established that none of the glycosaminoglycans in plasma are covalently linked to plasma proteins. All are isolated as complexes with plasma proteins in noncovalent linkages. The glycosaminoglycans in the low-charge fraction are bound with high affinity to a single plasma glycoprotein by a lectin-type bond that can be disrupted by a simple glycoside. The highcharge fraction contains three major proteins and several minor proteins associated with the glycosaminoglycans by both lectintype and ionic bonding. The plasma proteins associated with glycosaminoglycans represent <0.5% of the total plasma proteins.Little is known about the physiologic role of the plasma glycosaminoglycans as components of metabolic processes. Because glycosaminoglycans have been implicated in lipid metabolism and atherosclerosis, we tested all of these compounds, isolated in free form, on the in vitro hydrolysis of triglycerides by lipoprotein lipase. Plasma heparan sulfate stimulated the rate of this reaction severalfold. All other plasma glycosaminoglycans were inactive. Thus, plasma heparan sulfate may play an important role in plasma lipoprotein metabolism.

Heparin/heparan sulfate anticoagulant glycosaminoglycans in human plasma of healthy donors: preliminary study on a small group of recruits

“…All plasmatic glycosaminoglycans circulate in association with a number of proteins. The association between HSGAGs and plasma proteins was the object of several studies, but this notwithstanding, little is known about the physiological role of this strong association [3,6]. Indeed, plasmatic glycosaminoglycans, in particular HSGAGs, are so strongly associated with proteins that complete purification of HSGAGs from healthy individuals is quite a long and difficult process, unsuitable for routine analysis of plasmatic HSGAGs [7].…”

“…The glycosaminoglycans in tissues and cells can be found either free, or noncovalently associated with proteins and phospholipids [2]. In human plasma all glycosaminoglycans can be found [3], and CSGAGs and HSGAGs are the most abundant [4,5]. Both classes of glycosaminoglycans interact with plasma proteins; HSGAGs, however, show the tightest association with plasma proteins, and this characteristic renders their extraction and purification from plasma quite difficult [6,7].…”

Protein-Bound Heparin/Heparan Sulfates in Human Adult and Umbilical Cord Plasma

“…Endothelial cells produce and secrete heparin/heparan sulfates [1][2][3][4][5], small amounts of which have been isolated from normal plasma [6][7][8][9]. Human umbilical cord plasma is thought to contain more heparin-like activity than adult plasma [10], and a variety of human cancers have been reported to produce heparin/heparan sulfates [11][12][13][14].…”

Interaction of lipoprotein Lp(a) and low density lipoprotein with glycosaminoglycans from human aorta.

“…Apo a may be dissociated from Lp(a) by treating with disulfide reducing agents, 6 leaving "Lp(a-)", a lipoprotein that is chemically and immunochemically similar to LDL Apo a exhibits a considerable size heterogeneity ranging from 300 to 700 kD. 7 The carbohydrate content, notably that of M. Bihari Varga and E. Gruber are at the Second Department of Pathology, Semmelweis Medical University, Budapest, Hungary. M. Rotheneder, R. Zechner, and G. M. Kostner are at the Medical Biochemistry Department, University of Graz, Graz, Austria.…”

“…Major emphasis was given to lipoprotein-GAG complexes, because free GAG, but little PG, is found in circulating plasma. 7 .…”