Transition Temperature and Changes in Protein Structure
The analysis of keratin (wool or hair) by DSC is well established. This technique is used either on dry hair samples or more often in presence of water, generally scanning between 50C and 200C to detect any changes that may present an enthalpic peak.
As has been reported (“The mechanisms and stability of thermal transitions in hair keratin”, Milcazrek et al. Colloid Polymer Science 270, 1106-1115 (1992) keratin undergoes detectable transformations at various temperatures.
These temperatures depend on treatments that the hair has been subjected to; bleaching, for example, will decrease the transition peak temperature.
According to published results, these transitions are thought to be due to changes in keratin structure, cysteine bond arrangements or strongly bound water in the keratin. DSC can therefore provide insight into how a treatment may affect deep structural changes in the hair keratin.
We use a Perkin Elmer 8000 with auto sampler. The resulting thermograms are analysed for peak temperature and enthalpy. The example thermogram below is for bleached, untreated hair: