Peptide—protein interactions within human hair keratins

Abstract

We selected 1235 decapeptides from human hair proteins encoded by human genes of keratins and keratin associated proteins. The peptides were linked to glass arrays and screened for their affinity towards a solution of human hair extracted keratin fraction. Based on the physicochemical properties of the peptides, ten variables were studied: content of different types of amino acid side chains (cysteine, hydrophobic, polar, basic, acidic, aromatic rings, amide, alcohol side chains), isoelectric point, and net charge. We found differences statistically significant on the binding affinity of peptides based on their content of cysteine, hydrophobic and polar amino acids, mainly containing alcohols. These results point to the formation of hydrophobic interactions and disulfide bonds between small peptides and human hair keratins as the main driving forces for the interaction of possible cosmetic peptides, namely designed to strength human hair. As so, our results enlighten the nature of the interaction of keratin based materials with human hair, which are claimed to enhance hair fiber strength, and enable a more directed and sustained hair care peptide design.

Changing the shape of hair with keratin peptides

“…These peptides are based on fragments of human hair keratin and KAPs and were selected on the basis of a previous study which used a microarray of peptides. 34 Specically, the peptide sequences are based on keratin associated protein 5-3 (PepA), keratin associated protein 4-8 (PepB), keratin associated protein 9-7 (PepC), keratin type I cuticular Ha4 (PepD), keratin type I cuticular Ha5 (PepE), keratin associated protein 16-1 (PepF), keratin associated protein 5-9 (PepG) and keratin type II cuticular Hb5 (KP). The KP peptide has already been analysed in previous studies.…”

“…These peptides were selected based on a previous study of 1235 cysteine-containing peptides of all genes of human hair keratin and KAPs. 34 This study analysed the interaction of the peptides with keratin extracted from human hair, and the peptides with the best characteristics were selected for further analysis. Due to their high cysteine content and hydrophobic properties, these peptides are expected to present higher affinities towards the hair proteins.…”

“…Furthermore, decapeptides are small enough to be able to penetrate into the hair cortex, but 10 to 13 amino acids residues make these peptides big enough to provide enhancement of strength and restructuring of the hair protein linkage network. 10,16,30,32 Firstly, we made a comparative analysis to determine the best peptides, based on their amino acid sequences, isoelectric points, cysteine contents, and hydrophobic and polar amino acids 34 (Fig. 2A).…”

“…From the previous study with the microarray, the peptides were already known to interact with keratin extracted from human hair. 34 Here, the peptides were analysed regarding their ability to interact with the entire hair bre. Fig.…”

“…These peptides were selected from a previous broad study which analyzed over 1000 different peptides containing two to ve cysteines based on genes for human hair keratin and KAPs. 34 It is known that cysteine can be applied as a reducing agent for the substitution of environmentally harmful chemicals. 35 The origin of the peptides, their high cysteine content, and their hydrophobicity are intended to improve hair properties, enabling the restructuring and reinforcement of hair bres.…”