Maximum Extraction of Wool Proteins by Thiol-Urea Solutions

Abstract

The extraction of protein from wool fibers by alkaline thiol solutions containing urea has been re-examined with a view to achieving maximum extraction. The extent of extraction was generally less than that previously reported. Some samples of Merino wools (21 μm diameter) show marked differences in the extent of extraction, and the extractability is apparently related neither to the age of the sample nor to the lanthionine and lysinoalanine contents.

Keratin: dissolution, extraction and biomedical application

“…Oxidation methods have been reported in the literature for decades 22 with oxidizing materials such as formic or peracetic acids being the most frequently used acids to form a sulfonic acid (RSO 3 H). 16,23 The process is generally a time-consuming process with more than 24 h of reaction time required to obtain a reasonable yield. Depending on the presence or absence of disulfide bonds in the keratin structure, several subfractions can be obtained that can have different physical properties.…”

“…Inclusion of nitrogen in the process makes the procedure complicated and also, more importantly, the extracts from different batches give inconsistent compositions due to possible auto-oxidation caused by some trace impurities in the samples. 23 Obtaining an undegraded protein and high yield has been the major aim of many studies investigating the extraction of keratin from wool. However, in many of the reported studies that were carried out at high pH or high temperature, the protein was severely degraded and lanthionine was formed during the process.…”

“…However, in many of the reported studies that were carried out at high pH or high temperature, the protein was severely degraded and lanthionine was formed during the process. 23 Many of these published studies lacked information on the physical and biochemical properties of the obtained keratin. Therefore, the physicochemical properties of the extracted reduced keratin were not evaluated probably due to the laborious preparation methods and instability of the reduced keratin protein.…”

Characterisation of keratin biomass from butchery and wool industry wastes

“…However, almost all the data on extracted wool refer to reduced keratins [35,36]. The reducing agents often used are thiols (thioglycolic acid, dithiothreitol and 2-mercaptoethanol) and they are always used in combination with a protein denaturing agent, like urea, that breaks the hydrogen bonds [37,31].…”

Associations between intermediate filament protein and intermediate filament associated protein, and between intermediate filament associated protein and membrane protein, in wool

“…Maclaren [2] has discussed the nature of the possible covalent crosslinks in this insoluble residue. The insoluble residue accounted for about 30% of the original weight of the wool.…”