QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wood, N. Articles by Fillios, L. C. Search for Related Content PubMed PubMed Citation Articles by Wood, N. Articles by Fillios, L. C.

Bound Sugars in Hepatic Glycoproteins from Male Rats during Early Protein Depletion¹

Departments of Nutritional Sciences and Biochemistry, School of Graduate Dentistry and Medicine, Boston University Medical Center, Boston, MA 02118

One purpose of these experiments was to determine whether qualitative changes take place in the attached components of hepatic (post-mitochondrial) glycoproteins isolated from rats fed a low protein diet (5% casein) for 1 week. In the acid-insoluble fraction (I) no significant changes in bound fucose, galactose, glucose, hexosamines or sialic acids were seen after early depletion. However, it should be noted that there was a moderate decrease in the bound mannose. An isotope study showed a statistical decrease in the level of labeled (1-¹⁴C) from mannose in vitro (cpm per mg protein) but no difference was seen if the data is expressed as cpm per mg of bound mannose in (I). On the other hand, in the more sugar-rich acid-soluble fraction (S) significant increases in both bound mannose and glucose were seen with no change in the fucose level; none of the other bound carbohydrates seen in (I) were detected in (S). In the isotope study, using mannose as a precursor, no differences in the rate or level of uptake (cpm per mg of mannose or protein) in (S) were seen. Following early protein depletion, there is an apparent overall increase in sugar-rich glycoproteins in (S) but the question still remains as to whether this increase is due to an increase of specific mannose and glucose rich glycoproteins in (S) or whether more carbohydrate branching occurs. In any case, an adaptive phenomenon is suggested for maintaining the intracellular environment during periods of inadequate amino acid supply.

KEY WORDS: • acid-soluble glycoproteins • bound sugars • early protein depletion • hepatic glycoproteins

¹ This work represents part of a master's dissertation submitted by N. Wood. It was supported by funds from the Department of Nutritional Sciences.

Manuscript received 13 April 1979.