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J A Foster

Publications and source records attributed to J A Foster.

142 records · Page 8Linked to original sources
PubMed1976

Topography of human plasma alpha1-acid glycoprotein.

Human plasma alpha1-acid glycoprotein, whose linear amino acid sequence has recently been elucidated (Schmid et al. (1973), Biochemistry 12, 2711), was further investigated with regard to its topography. Nitration of this protein and subsequent elucidation of the structures of the peptides containing modified tyrosine indicated that residues 27, 37, 78, 115, 127, and 157 are free, 50 and 91 are in an intermediate state, and 65, 74, 110, and 142 are buried. CD measurements between pH 10 and 12 demonstrated that the buried tyrosines are strongly hydrogen bonded and are probably responsible to a considerable extent for the stability of this protein. Of the three tryptophans of this protein, residue 122 proved to be partially reactive with Koshland reagent while the other two (25 and 160) were found to be unreactive. The state of the two disulfide bonds, established by differential reduction and alkylation with specific reagents, was shown to be of an intermediate type. Using carboxymethylation with bromoacetate at pH 7.0 for 8 days, the three histidines (97, 100, and 171) and methionine 111 could be shown to be in intermediate states. All lysines were treated with trinitrobenzenesulfonate and thus were assumed to be free. Of the 40 carboxylic groups, which were amidated with glycine methyl ester, 32 including the 14 sialyl residues were found to be free, six in an intermediate and the remaining two in a buried state. The present study describes the states of almost half of the amino acid residues of alpha1-acid glycoprotein, a knowledge important for the construction of a preliminary three-dimensional model of this conjugated protein.

Amino Acid Sequence↗
PubMed1976

The synthesis of connective tissue protein in smooth muscle cells.

The synthesis of elastin by smooth muscle cells was clearly demonstrated by amino acid analyses and the presence of lysine-derived crosslinks. The values obtained were compatible with those found in amorphous elastin isolated from rabbit aortic tissue. Collagen synthesis by these same cells was monitored by the appearance of [14C] hydroxyproline when the cells were grown in the presence of [14C] proline. When the cells were pulsed with [14C] lysine, one could detect [14C] hydroxylysine and [14C] glucosylgalactosylhydroxylysine. Further evidence for the synthesis of elastin and collagen was the finding of radiolabelled epsilon-hydroxynorleucine and the reduced aldol condensate of two residues of allysine after reduction of [14C] lysine pulsed cells with NaBH4.

Animals↗
PubMed1975

Isolation of soluble elastin from lathyritic chicks. Comparison to tropoelastin from copper deficient pigs.

Tropoelastin was isolated from the aortas of chicks rendered lathyritic by treatment with beta-aminopropionitrile. The soluble elastin was judged homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis and possessed an estimated molecular weight of 70000. Automated sequential analysis revealed that the N-terminal region of the chick tropoelastin is very homologous to tropoelastin isolated from copper-deficient piglets. N-terminal analysis of a trypsin digest of chick tropoelastin showed that tyrosine frequently is found adjacent to lysine residues. This positioning of tyrosine residues may be significant in terms of a possible regulatory role in elastin cross-link formation.

Amino Acid Sequence↗
PubMed1975

Allophycocyanin from the filamentous cyanophyte, Phormidium luridum.

Allophycocyanin from the filamentous cyanophyte, Phormidium luridum, was purified by ammonium sulfate fractionation and ion exchange chromatography on brushite columns. The specific absorption coefficient (E 0.1% 1cm) of purified allophycocyanin was 6.1 in distilled water and 7.3 in 0.05 M potassium phosphate buffer (pH 7). Absorption maxima of allophycocyanin occurred at 650, 618 (shoulder), 350, and 275 nm. Circular dichroic spectra displayed positive ellipticity bands at 655 and 625 nm, and a major negative ellipticity band at 340 nm. Computer analysis of the circular dichroic spectrum of allophycocyanin from 207 to 243 nm indicated that the secondary structure contained 60% alpha helix and 40% beta form. The estimated molecular weight of allophycocyanin on Sephadex G-200 columns at pH 7.0 was 155,000. Electrophoretic examination of allophycocyanin on sodium dodecyl sulfate polyacrylamide gels revealed two subunits, alpha and beta, with apparent molecular weights of 17,300 and 19,000, respectively. Densitometric analysis of unstained gels at 600 nm indicated that one phycocyanobilin chromophore was associated with each subunit. Treatment of allophycocyanin with 12% formic acid or 8 M urea and subsequent removal of the denaturant yielded a derivative with spectroscopic characteristics similar to phycocyanin. Subsequent incubation in phosphate buffer (pH 7), but not in acetate buffer (pH 5) or in water, was accompanied by a progressive reappearance of absorption maxima at 650 and 618 nm (shoulder), and positive ellipticity bands at 655 and 617 nm. Automated sequence analysis of allophycocyanin (a) showed that the sequence of amino acids at the amino terminus of the alpha and beta subunits is different, (b) showed that the subunits occur in a ratio of 1:1, and (c) demonstrated sequence homology at the amino terminus of allophycocyanin, phycocyanin, and phycoerythrin.

Amino Acids↗
PubMed1975

The alpha and beta subunits of Cyanidium caldarium phycocyanin: properties and amino acid sequences at the amino terminus.

Phycocyanin was isolated and purified from the unicellular alga, Cyanidium caldarium. Subunits were prepared on a Bio-Rex-70 column developed stepwise with urea solutions (pH 1.9). The alpha subunit eluted in 8 M urea and the beta subunit eluted in 9 M urea. The alpha and beta subunits displayed absorption maxima at 660, 354, and 277 nm in 8 M and 9 M urea. The alpha:beta ratio of total absorbance under the 660-nm peak was 0.56 suggesting an alpha:beta phycocyanobilin chromophore ration of 1:2. On calibrated sodium dodecyl sulfate gels, the alphs subunit had an estimated molecular weight of 15,500 plus or minus 1100 and the beta subunit has an estimated molecular weight of 18,300 plus or minus 300. Minimum molecular weights based on one histidine residue per subunit were 16,300 for the alpha subunit and 18,750 for the beta subunit. Phycocyanin displayed a single visible absorption maximum at 625 nm and two positive circular dichroic bands at 632 and 610 nm. The alpha and beta subunits displayed single visible absorption maxima at 618 and 600 nm and single positive circular dichroic peaks at 620 and 585 nm, respectively. Two-dimensional maps of tryptic digests of the alpha and beta subunits revealed distinct patterns of peptides each of which was consistent with the lysine and arginine composition of these polypeptides. Maps of tryptic digests of phycocyanin contained 25 major peptides (a total of 27 lysine and arginine residues). Automated sequence analysis of separated subunits revealed a 70% homology within the first 27 residues at the amino terminus of the alpha and beta subunits of C. caldarium phycocyanin.

Amino Acid Sequence↗
PubMedDate not supplied

Effects of pH on protein binding of lidocaine.

Protein binding of lidocaine (2.5, 5, 10, and 20 microgram/ml in fresh plasma was studied from pH 5.6 to pH 9.8. Percent binding of lidocaine was inversely related to hydrogen-ion and lidocaine concentrations.

Anesthesia, Local↗
PubMedDate not supplied

Unilateral or asymmetric congenital ptosis, head posturing, and amblyopia.

PURPOSE: To determine the prognostic implication of compensatory head posturing in patients with unilateral or asymmetric congenital ptosis. METHODS: A retrospective review of 80 consecutive patients with unilateral or asymmetric congenital ptosis was performed. The presence of documented compensatory head posturing, age of onset, age of presentation, visual acuity, refraction, and amblyopia were recorded, and binocularity was tested. RESULTS: Five of seven (71%), patients with unilateral or asymmetric congenital ptosis and compensatory head posturing had amblyopia. All of these patients had straight eyes and four of the five amblyopic patients had anisometropia of less than 2 diopters (D). CONCLUSION: The high incidence of amblyopia in this group can occur in the absence of significant anisometropia and strabismus. This unusually high incidence of amblyopia in this subgroup of patients with unilateral or asymmetric congenital ptosis and compensatory head posturing warrants compulsive examination and prophylactic part-time occlusion therapy of the nonptotic eye until reliable vision testing can be performed.

Amblyopia↗