Open Access. Powered by Scholars. Published by Universities.®

Chemistry Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of South Carolina

Discipline
Keyword
Publication Year
Publication
Publication Type

Articles 751 - 760 of 760

Full-Text Articles in Chemistry

13C Nmr Investigation Of Nonenzymatic Glucosylation Of Protein, Carolyn I. Neglia, Helga J. Cohen, Albert R. Garber, Paul D. Ellis, Suzanne R. Thorpe, John W. Baynes Dec 1983

13C Nmr Investigation Of Nonenzymatic Glucosylation Of Protein, Carolyn I. Neglia, Helga J. Cohen, Albert R. Garber, Paul D. Ellis, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Nonenzymatic glucosylation of protein is initiated by the reversible condensation of glucose in its open chain form with the amino groups on the protein. The initial product is an aldimine (Schiff base) which cyclizes to the glycosylamine derivative. The aldimine can undergo a slow Amadori rearrangement to yield the relatively stable ketoamine adduct which is structurally analogous to fructose. 13C NMR has been used to characterize these early products of nonenzymatic glucosylation, using RNase A as a model protein. C-1 of the beta-pyranose anomer of the glycosylamine was identified at 88.8 ppm in the spectrum of RNase glucosylated approximately 1:1 …

Go to article

Nonenzymatic Glucosylation And Glucose-Dependent Cross-Linking Of Protein, Albert S. Eble, Suzanne R. Thorpe, John W. Baynes Aug 1983

Nonenzymatic Glucosylation And Glucose-Dependent Cross-Linking Of Protein, Albert S. Eble, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

A model system using RNase A has been established for studying the nonenzymatic glucosylation and glucose-dependent cross-linking of protein (Maillard reaction) under physiological conditions in vitro. The rate of glucosylation of RNase was first order in glucose. Glucosylation was accompanied by a comparable decrease in primary amino groups in the protein and lysine recoverable by amino acid analysis. Analysis of glucosylation reaction mixtures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of mercaptoethanol revealed the time-dependent formation of RNase dimer and trimer. The polymerization reaction was mixed order with respect to glucose concentration, but was approximately first order with …

Go to article

Nonenzymatic Glucosylation Of Rat Albumin: Studies In Vitro And In Vivo, James F. Day, Robert W. Thornburg, Suzanne R. Thorpe, John W. Baynes Oct 1979

Nonenzymatic Glucosylation Of Rat Albumin: Studies In Vitro And In Vivo, James F. Day, Robert W. Thornburg, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Incubation of rat serum with D-glucose in vitro resulted in nonenzymatic glucosylation of serum proteins. Analysis of freshly isolated rat albumin by ion exchange chromatography indicated that the glucosylated albumin accounts for 6.7.+-. 0.9% of total albumin in normal rat serum. Glucosylation of rat albumin in vitro was 1st order with respect to glucose and albumin concentrations and occurs primarily (> 90%) at intrachain lysine residues. Kinetic analysis and inhibition of glucosylation by aspirin suggest that 1 reactive lysine residue is the primary site of glucosylation. Less than 5% of the radioactivity from glucosyl-albumin was released as glucose or mannose …

Go to article

Enhanced Nonenzymatic Glucosylation Of Human Serum Albumin In Diabetes Mellitus, C. Earl Guthrow, Mary Ann Morris, James F. Day, Suzanne R. Thorpe, John W. Baynes Sep 1979

Enhanced Nonenzymatic Glucosylation Of Human Serum Albumin In Diabetes Mellitus, C. Earl Guthrow, Mary Ann Morris, James F. Day, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Use of an ion exchange chromatographic method and a colorimetric method with thiobarbituric acid showed that levels of nonenzymatically glucosylated serum albumin were increased in patients with poorly controlled diabetes mellitus compared to controls. The two methods correlated well (r = 0.99) and clearly discriminated between normal and poorly controlled diabetic populations. The levels of glycosylated hemoglobin were also measured in both populations. Several patients apparently in good control based on glycosylated hemoglobin measurements were found to have increased levels of glycosylated albumin. Because albumin has a shorter circulating half-life than does the human erythrocyte, the plasma concentration of glucosylated …

Go to article

Nonenzymatically Glucosylated Albumin: In Vitro Preparation And Isolation From Normal Human Serum, James F. Day, Suzanne R. Thorpe, John W. Baynes Feb 1979

Nonenzymatically Glucosylated Albumin: In Vitro Preparation And Isolation From Normal Human Serum, James F. Day, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Incubation of human serum with D-[6-3H]glucose resulted in the gradual accumulation of radioactivity in acid-precipitable material. Upon chromatography on Sephadex G-200, radioactivity was found associated with each of the major molecular weight classes of serum protein. Purified human serum albumin was also glucosylated in vitro upon exposure to D-[6-3H]glucose in phosphate-buffered saline. The glucosylated and unmodified albumins were separated by ion exchange chromatography. The physiological significance of these observations in vitro was confirmed by the isolation and quantitation of glucosylated albumin from normal human serum. Glucosylated albumin represents approximately 6 to 15% of total serum albumin in normal adults. The …

Go to article

[3H]‑Raffinose, A Novel Radioactive Label For Determining Organ Sites Of Catabolism Of Proteins In The Circulation, Jonathon Van Zile, Lee A. Henderson, John W. Baynes, Suzanne R. Thorpe Sep 1978

[3H]‑Raffinose, A Novel Radioactive Label For Determining Organ Sites Of Catabolism Of Proteins In The Circulation, Jonathon Van Zile, Lee A. Henderson, John W. Baynes, Suzanne R. Thorpe

Faculty Publications

The primary tissue sites of catabolism of plasma proteins with long circulating half-lives are unknown. It has been difficult to identify these sites because plasma proteins are delivered to tissues at relatively slow rates but are rapidly degraded intracellularly within lysosomes. Therefore, a tracer attached to protein is lost from the site of uptake before an amount sufficient for quantitation can accumulate. We hypothesized that sucrose (Glupal-2 /3Fruf) would be a useful label to circumvent this difficulty because of the stability of sucrose in lysosomes; and thus, sucrose should remain in tissue long after the protein to which it was …

Go to article

Effect Of Glycosylation On The In Vivo Circulating Half-Life Of Ribonuclease, John W. Baynes, Finn Wold Oct 1976

Effect Of Glycosylation On The In Vivo Circulating Half-Life Of Ribonuclease, John W. Baynes, Finn Wold

Faculty Publications

The circulating half-lives of the four isozymes of bovine pancreatic ribonuclease (RNases A, B, C, and D) have been determined in normal and in nephrectomized rats. The isozymes differ only in their glycosyl content. While A contains no sugars, B has a simple oligosaccharide (GlcNAc, Man,+), and C and D each have a complex oligosaccharide (GlcNAc, Man,., Gal, Fuc NeuAc%, and GlcNAc, Mans Gal, Fuc NeuAc,, respectively) attached to Asn-34 of the polypeptide chain. All four isozymes were cleared rapidly in normal rats (t,,, = 2 to 3 min), as expected on the basis of the established role of the …

Go to article

The Role Of A Dolichol-Oligosaccharide As An Intermediate In Glycoprotein Biosynthesis, An-Fei Hsu, John W. Baynes, Edward C. Heath Jun 1974

The Role Of A Dolichol-Oligosaccharide As An Intermediate In Glycoprotein Biosynthesis, An-Fei Hsu, John W. Baynes, Edward C. Heath

Faculty Publications

Incubation of mouse myeloma microsomes with GDP-[(14)C]mannose results in the biosynthesis of [(14)C]mannose phosphoryl dolichol [Baynes, J. W., Hsu, A.-F. & Heath, E. C. (1973) J. Biol. Chem. 248, 5693-5704] and a [(14)C]mannose- and N-acetylglucosamine (GlcNAc)-containing oligosaccharide derivative of dolichol. Thus, [(14)C]mannose phosphoryl dolichol and [(14)C]mannose-labeled oligosaccharide pyrophosphoryl dolichol were isolated from incubation mixtures by solubilization in 2% (w/v) Triton X-100 and the lipids were separated from small molecules by gel filtration fractionation. After removal of radioactive protein from the preparation, the two lipid derivatives were separated quantitatively by fractionation on a concanavalin A-Sepharose column; [(14)C]mannose phosphoryl dolichol was not …

Go to article

The Role Of Mannosyl-Phosphoryl-Dihydropolyisoprenol In The Synthesis Of Mammalian Glycoproteins, John W. Baynes, An-Fei Hsu, Edward C. Heath Aug 1973

The Role Of Mannosyl-Phosphoryl-Dihydropolyisoprenol In The Synthesis Of Mammalian Glycoproteins, John W. Baynes, An-Fei Hsu, Edward C. Heath

Faculty Publications

A mouse myeloma tumor was used as a model system to study the biochemical steps involved in the incorporation of mannose into glycoproteins. This tumor, MOPC-46B, synthesizes a K-type immunoglobulin light chain (K-46) which is a glycoprotein with a single oligosaccharide side chain containing mannose as one of its constituent sugars. MOPC-46B microsomal preparations contain enzymes which transfer mannose from the sugar nucleotide, GDPmannose, to endogenous lipid and protein acceptors. Formation of the mannolipid proceeds by the reversible transfer of mannose from GDP-mannose to an endogenous phospholipid. The mannolipid was purified and characterized by chemical methods and mass spectrometry as …

Go to article

Human Complement Protein C8: The “Hole” Story, James M. Sodetz Jan 1012

Human Complement Protein C8: The “Hole” Story, James M. Sodetz

Journal of the South Carolina Academy of Science

No abstract provided.

Go to article

First Prev