PubMed Health⌕ Search

Biomedical subjects

R L Synge

Publications and source records attributed to R L Synge.

At least 19 recordsLinked to original sources
PubMed1990

25 years of Science Citation Index--some experiences.

Science Citation Index (SCI) depends for intellectual content entirely on citations by authors, who are sometimes prodded by editors and referees. Its patchiness is therefore not surprising, but frequently it gives access to relevant and up-to-date documents not easily accessible by other means. Two contrasting "citation families" are described. The first family, dealing with the various ascorbic acid derivatives having C substitution at C-2, actually retrieved very nearly all the relevant documents (other than patent specifications) that were retrieved by a CAS ONLINE substructure search. Organic chemists are clearly careful authors. The second family, dealing with amino acid residues covalently bound in soil organic matter, yielded documents having surprisingly little overlap with those retrieved by using a carefully devised Boolean "profile" on the general subject index of Chemical Abstracts. This was only partly because SCI is beset by language-barrier problems to which Chemical Abstracts is immune. The SCI management might extend its journal coverage, but otherwise improvement can only come from a more serious attitude to placing references in primary publications. SCI remains a complement to, not a substitute for, other data-bases.

Abstracting and Indexing↗
PubMed1971

N-carbamoyl-2-(p-hydroxyphenyl)glycine from leaves of broad bean (Vicia faba L.).

1. dl-2-(p-Hydroxyphenyl)glycine was resolved through the bromocamphorsulphonate to give its d-isomer. The N-carbamoyl derivatives of these amino acids were synthesized. Circular-dichroism studies on these and related compounds, reported in a deposited Annex, helped to establish the optical configuration. 2. N-Carbamoyl-dl-2-(p-hydroxyphenyl)glycine was isolated from broad-bean leaves. It amounted to about 0.1% of the leaf dry matter. Racemization may or may not have occurred during the isolation. There were indications of the same compound in chicory and in savoy cabbage. Under weakly acidic conditions it was converted gradually into 5-(p-hydroxyphenyl)hydantoin. Both these compounds yielded 2-(p-hydroxyphenyl)glycine on acid hydrolysis. 3. The occurrence is discussed of 2-phenylglycine derivatives in Nature and of N-carbamoyl-amino acids and hydantoins in plants. 4. Gradient elution from anion-exchange resin with acetic acid, besides proving useful for the present work, gave useful separations of pyrrolidonecarboxylic acid and of some N-acetyl-amino acids. 5. Supplementary material (Annex 1: details of experimental work other than ultraviolet and circular-dichroism spectra; Annex 2: ultraviolet absorption and circular dichroism of d-2-phenylglycine and some related compounds) has been deposited as Supplementary Publication SUP 50003 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1971), 121, 7.

Carbamates↗
PubMed1970

An obstacle in preparing alloisoleucine.

Alloisoleucine, prepared from a mixture of racemic isoleucine-alloisoleucine diastereoisomers, can be heavily contaminated with isoleucine if the recrystallization of acetyl-dl-alloisoleucine is controlled by melting point only. Two commercial specimens were found to be thus contaminated.

Crystallization↗
PubMed1965

A search for O-polypeptidyl-ribonucleic acids in rabbit-reticulocyte ribosomes by electrophoresis in phenol-acetic acid-water systems.

1. When solutions of ;soluble' or transfer RNA (s-RNA) and of cytochrome c in phenol-acetic acid-water were mixed, intractable coacervates were formed. The addition to the solutions of various strong electrolytes prevented coacervation and allowed electrophoretic separation on filter paper. Protein migrates cationically, leaving RNA at or near the origin. The separation is aided by adsorption of RNA to the paper. Special arrangements were necessary to prevent contamination of the paper by ultraviolet-absorbing electrode-reaction products. 2. Binding of alkali-metal cations to RNA and some other associations were observed in such solvent systems. Possible effects of ionic association on mobilities are discussed. 3. Rabbit-reticulocyte ribosomes were subjected to electrophoresis as above, after their nascent-protein moiety had been labelled with [(14)C]valine in the intact cell. Most of the radioactivity migrated with the ribosomal protein; such protein as remained near the origin with the RNA had valine of lower specific radioactivity. 4. Molecular-sieve chromatography in phenol-acetic acid-water indicated that the nascent-protein moiety was not of markedly lower molecular weight than the average for the ribosomal proteins. 5. These results are very tentatively taken to mean that the nascent-protein moiety of ribosomes so prepared is not O-polypeptidyl-s-RNA. It is postulated that, in the course of adding each amino acid residue, the growing polypeptide chain is transferred from ester linkage with s-RNA to linkage with ribosomal protein through its carboxyl group, perhaps by ester linkage to an alcoholic group. The two types of intermediate, O-polypeptidyl-s-RNA and polypeptidyl-protein, would be found in different proportions, depending on the isolation procedure used. Some implications and possible tests of this hypothesis are discussed.

Acetates↗