A Novel Method to Restore the Hair Crystalline and Amorphous Structures: Combination Treatments of Glycine Betaine and Macromolecular Hydrolyzed Keratin Proteins
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Presented by: Takayuki Togashi
Background
The structure of hair is roughly divided into external cuticle and internal cortex, most of which are composed of proteins. About half of the cortex is composed of fibrous proteins. Cylindrical intermediate filaments (IFs) rich in α-helical structures assemble to form crystallites. The other half is globular proteins. Amorphous keratin associate proteins (KAPs), a random coil structure, surrounds the IFs. Meanwhile, chemical treatments such as hair-coloring and permanent-waving are known to cause the denaturation and outflow of IFs and KAPs. At present, countermeasures against denaturation and outflow are completely inadequate, and ingredients to improve mainly the texture have been studied so far. However, we considered important to develop a "repair" method that brings the damaged cortex closer to its original structure. Recently, we focused on the stabilization of protein structure by glycine betaine and reported a method to repair the hair crystalline structure denaturation by its strong hydration ability.
Objectives
In order to restore the original structure of hair cortex, we aimed to develop a method to replenish the crystalline and amorphous structures that have been eluted, as well as to improve the recovery of the denatured structure by glycine betaine.
Results
Development of "Cortex Crystalline and Amorphous Structures Repair Method"
We used a tensile testing as evaluation criteria, to screening combination of glycine betaine and various ingredients and treatment conditions. The results showed that hydrolyzed keratin proteins, especially macromolecular proteins that retain the structures of IFs or KAPs, combined with glycine betaine, restored tensile stress to a level not seen in the past.
Thus, we further investigated the interaction between glycine betaine and macromolecular hydrolyzed keratin proteins, examined the structural resilience of cortex, and speculated on the mechanism of reshaping.
Evaluation of the interaction between glycine betaine and macromolecular hydrolyzed keratin proteins
Circular dichroism spectroscopy showed that mixing glycine betaine with hydrolyzed keratin proteins restored the secondary structures. Macromolecular hydrolyzed keratin proteins derived from IFs or KAPs showed peak patterns of α-helix or random coil, respectively. The patterns were highlighted by interaction with glycine betaine, suggesting that the more compact native structure was restored. In addition, it was speculated that the interaction between the denatured keratin proteins of hair cortex and glycine betaine will also occur.
Evaluation of the structural restoration effects
The effects of treatments on damaged hair were evaluated by structural analysis of crystalline and amorphous: (a) in-air and in-water tensile tests, (b) high-pressure differential scanning calorimetry, and (c) small-angle x-ray scattering measurement using synchrotron radiation. Combination treatment of glycine betaine with IFs-derived macromolecular hydrolyzed keratin protein resulted in (a) significant increases in the tensile stresses both in-air and in-water, (b) an increase in the enthalpy of denaturation, and (c) a large recovery of peak intensity corresponding to the IF-IF lattice plane spacing. These were thought to indicate that the crystalline structure could be adequately repaired. In contrast, the combination of glycine betaine and KAPs-derived macromolecular hydrolyzed keratin protein resulted in (a) a significant improvement of tensile stress in-air only, (b) an increase in the denaturation peak temperature, and (c) a large recovery in the degree of orientation of IFs. These were thought to indicate that the amorphous structure could be adequately repaired.
Speculation on the mechanism of structural recovery
Combinational treatments produced significant structural resilience, not seen with glycine betaine alone or with macromolecular hydrolyzed keratin protein alone. As the reason, the interaction between glycine betaine and macromolecular hydrolyzed keratin proteins should make the original compact structures of the proteins, which might penetrate inside hair sufficiently and fill the eluted area, making it easier to be settled. Furthermore, the process by which the macromolecular hydrolyzed keratin protein restored its native secondary structure by interacting with glycine betaine may facilitate the restoration of the denatured cortex proteins.
Conclusion
We have developed the combination treatments of glycine betaine and macromolecular hydrolyzed keratin proteins to restore the original cortex structure sufficiently. Our results suggested that using this technique provides a radical way of improving the denaturation and efflux of keratin proteins, which are the essence of hair damage caused by chemical treatments.
We believe that this combination processing technique is a novel "repair" method that restores the original structure of hair cortex, with clearly theory and effects.
The structure of hair is roughly divided into external cuticle and internal cortex, most of which are composed of proteins. About half of the cortex is composed of fibrous proteins. Cylindrical intermediate filaments (IFs) rich in α-helical structures assemble to form crystallites. The other half is globular proteins. Amorphous keratin associate proteins (KAPs), a random coil structure, surrounds the IFs. Meanwhile, chemical treatments such as hair-coloring and permanent-waving are known to cause the denaturation and outflow of IFs and KAPs. At present, countermeasures against denaturation and outflow are completely inadequate, and ingredients to improve mainly the texture have been studied so far. However, we considered important to develop a "repair" method that brings the damaged cortex closer to its original structure. Recently, we focused on the stabilization of protein structure by glycine betaine and reported a method to repair the hair crystalline structure denaturation by its strong hydration ability.
Objectives
In order to restore the original structure of hair cortex, we aimed to develop a method to replenish the crystalline and amorphous structures that have been eluted, as well as to improve the recovery of the denatured structure by glycine betaine.
Results
Development of "Cortex Crystalline and Amorphous Structures Repair Method"
We used a tensile testing as evaluation criteria, to screening combination of glycine betaine and various ingredients and treatment conditions. The results showed that hydrolyzed keratin proteins, especially macromolecular proteins that retain the structures of IFs or KAPs, combined with glycine betaine, restored tensile stress to a level not seen in the past.
Thus, we further investigated the interaction between glycine betaine and macromolecular hydrolyzed keratin proteins, examined the structural resilience of cortex, and speculated on the mechanism of reshaping.
Evaluation of the interaction between glycine betaine and macromolecular hydrolyzed keratin proteins
Circular dichroism spectroscopy showed that mixing glycine betaine with hydrolyzed keratin proteins restored the secondary structures. Macromolecular hydrolyzed keratin proteins derived from IFs or KAPs showed peak patterns of α-helix or random coil, respectively. The patterns were highlighted by interaction with glycine betaine, suggesting that the more compact native structure was restored. In addition, it was speculated that the interaction between the denatured keratin proteins of hair cortex and glycine betaine will also occur.
Evaluation of the structural restoration effects
The effects of treatments on damaged hair were evaluated by structural analysis of crystalline and amorphous: (a) in-air and in-water tensile tests, (b) high-pressure differential scanning calorimetry, and (c) small-angle x-ray scattering measurement using synchrotron radiation. Combination treatment of glycine betaine with IFs-derived macromolecular hydrolyzed keratin protein resulted in (a) significant increases in the tensile stresses both in-air and in-water, (b) an increase in the enthalpy of denaturation, and (c) a large recovery of peak intensity corresponding to the IF-IF lattice plane spacing. These were thought to indicate that the crystalline structure could be adequately repaired. In contrast, the combination of glycine betaine and KAPs-derived macromolecular hydrolyzed keratin protein resulted in (a) a significant improvement of tensile stress in-air only, (b) an increase in the denaturation peak temperature, and (c) a large recovery in the degree of orientation of IFs. These were thought to indicate that the amorphous structure could be adequately repaired.
Speculation on the mechanism of structural recovery
Combinational treatments produced significant structural resilience, not seen with glycine betaine alone or with macromolecular hydrolyzed keratin protein alone. As the reason, the interaction between glycine betaine and macromolecular hydrolyzed keratin proteins should make the original compact structures of the proteins, which might penetrate inside hair sufficiently and fill the eluted area, making it easier to be settled. Furthermore, the process by which the macromolecular hydrolyzed keratin protein restored its native secondary structure by interacting with glycine betaine may facilitate the restoration of the denatured cortex proteins.
Conclusion
We have developed the combination treatments of glycine betaine and macromolecular hydrolyzed keratin proteins to restore the original cortex structure sufficiently. Our results suggested that using this technique provides a radical way of improving the denaturation and efflux of keratin proteins, which are the essence of hair damage caused by chemical treatments.
We believe that this combination processing technique is a novel "repair" method that restores the original structure of hair cortex, with clearly theory and effects.