Terminal Amino Groups in Wool and S-Carboxymethyl Kerateine 2

Abstract

The N-terminal residues of Merino 64's quality wool and of a purified protein derivative extracted from it, S-carboxymethyl kerateine 2, have been determined. A similar total N-terminal residue content is present in both wool and S�carboxymethyl kerateine 2 comprising glycine, serine, threoni~e, aspartic acid, glutamic acid, and alanine. These occur in different proportions in the two materials and valine is an additional N-terminal amino acid present only in wool.

The Elastic Properties of Chemically Modified Wools and Their Implications for Theories of Wool Structure

“…Since the evidence rules out peptide bond fission during the isolation of the proteins from wool [8,32 J, from the chemical nature of the techniques used to isolate them, the simplest conclusion which can be drawn is that in the fiber these units are joined end to end through disulfide bonds, as has been proposed earlier 1191. It is (ii'ffictilt at present to see how direct evidence for this suggestion can be obtained, but it has long been a tenet of polymer chemistry that macroscopic elastic properties can ---,-, be related to molecular structure.…”

The Isolation and Properties of Some Soluble Proteins from Wool III. The Heterogeneity of the Low-Sulphur Wool Protein Scmka2

“…For example, O'Donnell, Thompson, and Inglis (1962) recently found N-acetyl groups in a low-sulphur wool S-carboxymethyl kerateine, which, if all were N-terminal, would be equivalent to a minimum molecular weight of about 25,000. Previously Thompson (1957) and Bradbury (1958) found N-and C-terminal end groups in small amounts, which in the case of the N -terminal residues were made up of six different amino acid residues, totalling to give 1 mole in 62,000 g of protein.…”

A Method for the Isolation of Dnp-Cyteic Acid and Its Application to the Determination of N-Terminal Half-Cystine Residues in Wool.

“…The results of analyses for DNP-cysteic acid in hydrolysates of oxidized DNf'<wool are shown in Table 1. The first determination was made on DNP-vvool prepared from 64's top and the others on the virgin Merino wool, 64's quality, previously examined (Thompson 1957) for N-terminal residues. Sample 1 was from DNP-V\Tool previously used while sample 2 was a freshly prepared sample.…”

“…Quantitatively, terminal half-cystine or cystine groups form the second most abundant of these. It must be remembered, however, that the correction factors for the destruction of DNP-glycine, the most abundant terminal amino acid, and DNP-cysteic acid (Table 2) are considerably higher than those for the other DNP-amino acids isolated (Thompson 1957) and consequently less confidence can be placed on these values.…”