The catabolism of plasma glycoproteins in normal and injured rats.
The catabolism of (14)C-labelled plasma glycoprotein in rats was studied after injecting homologous plasma protein labelled in the N-acetylglucosamine and sialic acid moieties. In normal animals the catabolism was approximately described by a four-compartment model. The fractional rate of catabolism of the plasma-protein amino sugar was found to be 0.0305hr.(-1), corresponding to the degradation of 2.75mumoles/hr. The (14)C label was eliminated from the animals largely as carbon dioxide with a small proportion appearing in the urine. Freely circulating amino sugars or glycopeptides did not appear in the plasma as a result of the catabolic processes, and there was no evidence that the protein-bound amino sugars were reutilized in biosynthetic processes. A study of the distribution of (14)C label in the carcasses of animals 24hr. after injection provided evidence that the gastrointestinal tract accounted for 25-38% of the total catabolic pool; the lungs, kidneys, spleen and liver also appeared to contribute to catabolism. Studies were conducted with rats that had been treated with turpentine to induce an inflammatory reaction; the results could not be analysed kinetically, since the metabolism of plasma proteins in these animals did not appear to be in a steady state. The injected plasma protein disappeared from the intravascular pool more quickly than in normal animals, but there were no significant differences in the rates of excretion of the (14)C label.
D000606:Amino Sugars / Q000378:metabolism; D000818:Animals; D001798:Blood Proteins / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes; D004064:Digestive System / Q000378:metabolism; D005944:Glucosamine; D006023:Glycoproteins / Q000378:metabolism*; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D009438:Neuraminic Acids; D051381:Rats; D013154:Spleen / Q000378:metabolism; D014425:Turpentine; D014556:Urine / Q000032:analysis
D000606:Amino Sugars; D001798:Blood Proteins; D002247:Carbon Isotopes; D006023:Glycoproteins; D009438:Neuraminic Acids; D002245:Carbon Dioxide; D005944:Glucosamine; D014425:Turpentine
J Clin Invest. 1967 Jan;46(1):10-20
6018743
Am J Physiol. 1960 Apr;198:814-8
14404800
J Biol Chem. 1959 Apr;234(4):742-8
13654254
J Biol Chem. 1968 Sep 10;243(17):4564-73
5684010
J Gen Physiol. 1959 Nov;43:415-44
14436924
Proc Soc Exp Biol Med. 1961 Jan;106:124-7
13790267
Ann N Y Acad Sci. 1961 Aug 31;94:23-30
13775383
J Biol Chem. 1964 Apr;239:1134-41
14165920
Nature. 1963 Sep 14;199:1096-7
14066949
J Biol Chem. 1965 May;240:1882-8
14299605
J Biol Chem. 1965 Oct;240(10):3707-13
5842047
Am J Physiol. 1961 Jun;200:1301-6
13751813
Biochem J. 1968 Jun;108(2):275-80
5665891