The occurrence of bis-(2-amino-2-carboxyethyl) trisulphide in hydrolysates of wool and other proteins

Chemical composition of the high- and low-sulphur Romney crossbred wools

“…This increase is twice that of Merino 64s wools as a result of intravenous and abomasal infusion with L-cysteine (Kulkarni 1969). The figures for total percentage sulphur calculated from cystine and cysteine may be low because of reported hydrolytic decomposition of cystine to volatile polysulphides (Fletcher & Robson 1963) Table 2 clearly show that the wools of supplemented sheep have a greater high-sulphur index (sum of a-helixdepleting amino acids) and a smaller a-helix index (sum of a-helix-favouring amino acids) than wools from unsupplemented sheep. The average ratios of a-helix index to high-sulphur index for the supplemented and unsupplemented wools respectively are 1.15 and 1.39.…”

Control of Aminolaevulinate Synthetase in Rhodopseudomonas spheroides

“…The growth and harvesting of organisms, preparation of cell-free extracts, deter mination of dry weight and protein, assay of ALA synthetase activity, assay of the activator activity of sulphur compounds and the preparation of crude and partially purified low activity ALA synthetase have all been described previously [Neuberger et ah, 1973a], Ninhydrin positive compounds were estimated as described by Rosen [1957] and cyanide-labile sulphur as described by Fletcher and Robson [1963]. Radioactivity was measured on a Mark I liquid scintillation system (Nuclear Chicago, 111., USA).…”

“…An alternative explanation was that on acid treatment, compounds with a higher activator activity than cystine were formed. Fletcher and Robson [1963] hydrolysed [a5S]-labelled wool in 6 mol/1 HC1 for 48 h and found a number of radio active compounds apart from cystine and methionine on chromatograms. One of these compounds was identified as the trisulphide of cystine (bis-[2-amino-2-carboxyethyl]trisulphide); trace amounts of this com- pound were also detected in an aged acid solution of [35S]-cystine.…”

“…One of these compounds was identified as the trisulphide of cystine (bis-[2-amino-2-carboxyethyl]trisulphide); trace amounts of this com- pound were also detected in an aged acid solution of [35S]-cystine. Org anic polysulphides are estimated by cyanolysis followed by reaction of the thiocyanate formed with ferric ions [Fletcher and Robson, 1963], A sample of acid-treated L-cystine was fractionated on Dowex 50 by step-wise elution with HC1 ( fig. 2).…”

γ-Radiolysis of disulfides in aqueous solution. II. D-Penicillamine disulfide

“…This sample was chromatographically pure except for traces of the trisulfide (PenSSSPen) and was used for Can Penicillamine Trisuljide (D,P'-divalyltrisulfide; PenSSSPen) Preparation of this compound was attempted by the methods described by Fletcher and Robson for preparation of cystine trisulfide (CySSSCy) (15). The following preparation was the most successful.…”