Healthy Processes in Relation to Proteoglycans and Glycosaminoglycans

Until recently, the work in this area has been insuflScient to warrant its review, but some papers on the biochemistry and pathophysiology of connective tissue (F9) are relevant. In consideration of the reports available, it must be borne in mind that comparisons made outside a particular circle of experiments may be invalid on account of the different conditions of the subjects, and conditions and methods for isolation, separation, and measurement of the macromolecules. Many such methods both for tissues and fluids have been reported (see reviews cited in Section 1.1), and it is imperative to ensure that the isolation and separation processes are effective (see B15, K12). Microscale methods have been devised to function on a few micrograms of material for component analysis (e.g., B16 see K17), but more particularly for the eomplete identification of a glycosaminoglycan on a basis of chemical structure (e.g., B13, B14). 

Some of the common enzymes that may or may not degrade proteoglycans, and therefore are relevant to a discussion on these enzymic processes, have been surveyed (M46, V2). In considering the enzyme-catalyzed breakdown of a proteoglycan, it is to be remembered that breakage may occur in the carbohydrate and protein in any order, and therefore that breakdown does not occur in the reverse order of biosynthesis. From the viewpoint of proteolysis of the proteoglycans, a number of 

Since urinary glycosaminoglycans have become a popular interest, it is appropriate to mention that the normal excretion rate of glycosaminoglycans is 3.8 and 6.0 mg per day for women and men, respectively (D25) but with large individual variations. On account of diurnal and excretion rate variations some search has been made for the existence 

Correlation between increased dermatan sulfate contents, calcification and decreased flexibility of tissue on aging is explicable in terms of the greater association with calcium of this glycosaminoglycan. Association with divalent cations promotes the numlier of interchain linkages (A9) thus decreasing the possibility of movement between molecules. 

Young human placenta contains more glycosaminoglycan than term placenta (L9). Although there are similar quantities of hyaluronic acid and chondroitin 4- and 6-sulfates, the younger placenta contains a greater proportion of chondroitin. The chondroitin sulfates of the early tissue also contain a higher proportion of unsulfated disaccharide units, and the dermatan sulfate of the young tissue is more susceptible to hyaluroni-dase (EC 3.2.1.35) than term tissue. 

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