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R G Reed

Publications and source records attributed to R G Reed.

At least 37 records · Page 2Linked to original sources
PubMed1987

Bromcresol purple dye-binding methods underestimate albumin that is carrying covalently bound bilirubin.

We used automated and manual versions of two commonly used dye-binding methods for albumin to quantify albumin that had been modified by covalent addition of bilirubin. Dye-binding methods based on reaction with bromcresol purple underestimated the modified albumin by as much as 29%. Dye-binding methods based on reaction with bromcresol green were unaffected by the presence of covalently attached bilirubin. Neither method was affected by the presence of noncovalently bound bilirubin.

Bilirubin↗
PubMed1986

Location of long chain fatty acid-binding sites of bovine serum albumin by affinity labeling.

Affinity labeling with palmitic acid was used to identify long chain fatty acid-binding sites of bovine serum albumin. [1-14C]Palmitic acid was activated by esterification with N-ethyl-5-phenyl-isoxazolium-3'-sulfonate (Woodward's Reagent K). The product was purified by chromatography and shown to compete with unesterified fatty acids for binding sites on bovine serum albumin. Activated [14C]palmitic acid coupled covalently to albumin producing [14C]palmitoyl-albumins containing from 0.12 to a maximum of 6.9 mol of attached label per mol of albumin. The presence of the covalently attached affinity label depressed binding of other long chain fatty acids to albumin. Albumin carrying 1 eq. of [14C]palmitate was cleaved using cyanogen bromide, pepsin, and trypsin. Radioactive peptides were isolated by high pressure liquid chromatography. Three peptides accounted for greater than 90% of the label. Residues labeled with [14C]palmitate were identified as Lys-116, Lys-349 and Lys-473, and the relative distribution of label was 10, 45, and 45% respectively, consistent with the presence of two strong binding sites in the COOH-terminal half of albumin and a somewhat weaker site in the NH2-terminal half.

Affinity Labels↗
PubMed1986

Limitations of the rat remnant kidney model of chronic renal failure: absence of calcium oxalate tissue injury.

We have studied the rat remnant kidney model as a tool to assess the impact of secondary oxalosis on renal failure. Although the plasma of uremic rats demonstrated increased levels of oxalic acid, deposits of oxalate crystals in tissue were not observed. The absence of such deposits in the remnant kidney, as well as other tissues, may be due to a lesser degree of hyperoxalemia observed in the rat compared to man or may reflect that uremic deaths among the experimental animals occurred prior to formation of detectable calcium oxalate deposition. We conclude that the rat remnant kidney is not a suitable model to study the impact of uremic oxalosis in man.

Animals↗
PubMed1984

Oxalate removal by hemodialysis in end-stage renal disease.

Because of mounting evidence of precipitation of calcium oxalate in the soft tissues of patients with end-stage renal disease (ESRD) on maintenance hemodialysis, the plasma oxalate concentrations and calculated dialysis removal of oxalate were studied in seven patients without evidence of either primary or absorption hyperoxaluria prior to ESRD. A reversed-phase high-pressure liquid chromatographic method was developed to quantitate serum oxalate. Mean value +/- SE in four healthy controls was 28 +/- 5 mumol/L, and in the seven patients it was 187 +/- 15 mumol/L predialysis and 89 +/- 11 mumol/L postdialysis. Oxalate deposition in the soft tissues of ESRD patients is the consequence of sustained hyperoxalemia. Oxalate removal by dialysis was calculated from the four-hour oxalate clearance. Since the ionic radii of phosphate and oxalate are similar, total oxalate clearance was calculated midpoint of dialysis. Mean oxalate removal/dialysis was 3.01 +/- 0.283 mmol. On a daily basis this value was 1.645 +/- 0.155 mmol, which is about threefold the normal oxalate excretion rate. It is not significantly different from the excretion rate in absorption oxalurias but is less than that in primary hyperoxaluria. Therefore, it is concluded that hyperoxalemia in ESRD results from loss of renal excretion, failure of hemodialysis to remove enough oxalate to maintain a normal serum concentration, and increased intestinal absorption of oxalate and/or increased endogenous production.

Adult↗
PubMed1983

Preparation of fragments 505-582 and 505-573 of bovine serum albumin.

Peptic fragment 505-582 of bovine serum albumin, the "Phe" fragment, has been found useful in several laboratories for studies of antigenic sites, ligand binding and metabolism. It contains the entire carboxyterminal loop, Loop 9, of the albumin molecule. We present an improved preparation of this peptide. Peptide 505-582 is obtained in about 9% yield, along with a similar yield of the closely associated peptide 505-573 arising from a second peptic cleavage. The unusual ultraviolet absorption spectrum of these peptides shows triple maxima near 259 nm reflective of the high phenylalanine content and the total absence of tyrosine and tryptophan.

Amino Acids↗
PubMed1980

Sequence of residues 400--403 of bovine serum albumin.

A large tryptic peptide of bovine serum albumin (residues 377--582) was subjected to 32 cycles of Edman degradation to determine the sequence of the last remaining unknown segment of this protein. Residues 400--403 were identified as gly-Phe-Gln-Asn. Amide assignments were also made at positions 388 (glutamine), 389 (asparagine), 391 (aspartic acid) and 392 (glutamine).

Amino Acid Sequence↗
PubMed1980

Ligand-binding properties of proalbumin Christchurch.

Proalbumin Christchurch, a circulating variant of human serum albumin, is secreted from the liver without cleavage of the hexapeptide situated at the N-terminal end of the peptide chain of proalbumin. We compared ligand-binding properties of proalbumin Christchurch and of normal albumin A from the same individual in order to test the effect of the presence of the hexapeptide. The two albumin forms exhibited similar affinities for palmitate, bilirubin, 8-anilinonaphthalene-1-sulphonate and Bromocresol Green. The patterns of endogenous fatty acids bound to the two forms of albumin were slightly different, although the differences were probably not of physiological significance. From these studies it would appear that the propeptide of proalbumin does not alter the protein conformation in such a way as to alter binding sites for organic anions.

Anilino Naphthalenesulfonates↗
PubMed1977

Immunochemical studies of fragments of bovine serum albumin.

Antigenic properties of 14 fragments of bovine albumin were measured using antisera to albumin and to two of its fragments. All seven fragments larger than 21,000 daltons formed immune precipitates. Although immune precipitates were not formed with smaller fragments, inhibition tests indicated the presence of antigenic sites on several of these fragments as well. The results predict the occurrence of six or more antigenic determinants and allow assignment of their positions in the parent molecule. These sites are distributed along the entire protein chain, with the sites of greatest antibody affinity situated in the COOH-terminal region. Evidence is presented that some sites are homologous, reacting with the same populations of antibodies, and that other sites are unique, binding to an exclusive population of antibodies.

Antibodies↗
PubMed1977

Kinetics of bilirubin binding to bovine serum albumin and the effects of palmitate.

The binding of bilirubin to bovine serum albumin has been determined to be a second order process, first order in each reactant. Formation of the bilirubin-albumin complex was observed as an increase in absorbance at 480 nm by stopped flow spectrophotometry. The effect of long chain fatty acid on the binding of bilirubin was investigated at palmitic acid levels of 0 to 7 mol/mol of albumin at 37 degrees and pH 7.4. The second order rate constant is 1.5 X 10(6) M-1 S-1 when the palmitate/albumin ratio is less than 5 and drops to 0.5 X 10(6) M-1 S-1 when the palmitate/albumin ratio reaches 6. The equilibrium association constant for the bilirubin-albumin complex is 5.5 X 10(6) M-1 when the palmitate/albumin ratio is less than 1, 18 X 10(6) M-1 when the palmitate/albumin ratio is between 1 and 5, and 3 X 10(6) M-1 when the palmitate/albumin ratio is greater than 5. The mechanism of the effect of palmitate varies with the total palmitate level. At low molar ratios, addition of palmitate has no effect on the association rate but decreases the dissociation rate. At high molar ratios, addition of palmitate decreases the association rate and increases the dissociation rate. It is suggested that palmitate affects the ability of the protein to undergo the conformational changes needed to accommodate bilirubin.

Bilirubin↗