1-Aminoanthracene Transduction into Liposomes Driven by Odorant-Binding Protein Proximity

Biotechnological applications of mammalian odorant-binding proteins

The olfactory system of mammals allows the detection and discrimination of thousands of odors from the environment. In mammals, odorant-binding proteins (OBPs) are considered responsible to carry odorant molecules across the aqueous nasal mucus to the olfactory receptors (ORs). The three-dimensional structure of these proteins presents eight antiparallel β-sheets and a short α-helical segment close to the C terminus, typical of the lipocalins family. The great ability of OBPs to bind differentiated ligand molecules has driven the research to understand the mechanisms underlying the OBP function in nature and the development of advanced biotechnological applications. This review describes the role of mammalian OBPs in the olfactory perception, highlighting the influence of several key parameters (amino acids, temperature, ionic strength, and pH) in the formation of the OBP/ligand complex. The information from the literature regarding OBP structure, affinity, the strength of binding, and stability inspiring the development of several applications herein detailed.

Current and potential biotechnological applications of odorant-binding proteins

Odorant-binding proteins (OBPs) are small soluble proteins whose biological function is believed to be facilitating olfaction by assisting the transport of volatile chemicals in both vertebrate and insect sensory organs, where they are secreted. Their capability to interact with a broad range of hydrophobic compounds combined with interesting features such as being small, stable, and easy to produce and modify, makes them suitable targets for applied research in various industrial segments, including textile, cosmetic, pesticide, and pharmaceutical, as well as for military, environmental, health, and security field applications. In addition to reviewing already established biotechnological applications of OBPs, this paper also discusses their potential use in prospecting of new technologies. The development of new products for insect population management is currently the most prevailing use for OBPs, followed by biosensor technology, an area that has recently seen a significant increase in studies evaluating their incorporation into sensing devices. Finally, less typical approaches include applications in anchorage systems and analytical tools. KEY POINTS: • Odorant-binding proteins (OBPs) present desired characteristics for applied research. • OBPs are mainly used for developing new products for insect population control. • Incorporation of OBPs into chemosensory devices is a growing area of study. • Less conventional uses for OBPs include anchorage systems and analytical purposes. Graphical Abstract.

Crystallin Fusion Proteins Improve the Thermal Properties of Hair

Styling hair with straightening irons is a popular daily hair routine that significantly damage the hair keratin fiber due to the high temperature applied. In this study, we investigate the effect of two fusion proteins based on the human eye γD-crystallin conjugated with a keratin-based peptide (KP-Cryst Wt and KP-Cryst Mut) on hair exposed to thermal damage. The mutant form was designed to improve protein stability and promote interaction with the hair. Through the study, it was demonstrated the protection of Asian and Caucasian virgin hair's structure by the pretreatments with the KP-Cryst fusion proteins. After hair thermal exposure, a higher water content was quantified by TGA on the hair fibers pretreated with the fusion proteins (about 38% for the KP-Cryst Wt and 44% for the KP-Cryst Mut). Also, negligible alterations in hair fibers' stiffness were observed after iron application, demonstrating the proteins capacity to effectively prevent the conversion of keratin α-helix structure into β-sheets. The results proved the capacity of the fusion proteins to bind to hair and protect it against high temperatures', supporting the development of new formulations based on the KP-Cryst proteins.

Release of Fragrances from Cotton Functionalized with Carbohydrate-Binding Module Proteins

Perspiration as a response to daily activity and physical exercise results in unpleasant odors that cause social unrest and embarrassment. To tackle it, functional textiles incorporating fragrances could be an effective clothing deodorizing product. This work presents two strategies for the release of β-citronellol from functionalized cotton with carbohydrate-binding module (CBM)-based complexes (OBP::GQ₂₀::CBM/β-citronellol-approach 1 and CBM::GQ₂₀::SP-DS3-liposome/β-citronellol-approach 2). CBM from Cellulomonas fimi was fused with the odorant-binding protein (OBP::GQ₂₀::CBM) and with an anchor peptide with affinity to the liposome membrane (CBM::GQ₂₀::SP-DS3). In approach 1, OBP fusion protein served as a fragrance container, whereas in approach 2, the fragrance was loaded into liposomes with a higher cargo capacity. The two strategies showed a differentiated β-citronellol release profile triggered by an acidic sweat solution. OBP::GQ₂₀::CBM complex revealed a fast release (31.9% and 25.8% of the initial amount, after 1.5 and 24 h of exposure with acidic sweat solution, respectively), while the CBM::GQ₂₀::SP-DS3-liposome complex demonstrated a slower and controlled release (5.9% and 10.5% of the initial amount, after 1.5 and 24 h of exposure with acidic sweat solution, respectively). Both strategies revealed high potential for textile functionalization aimed at controlled release of fragrances. The OBP::GQ₂₀::CBM/β-citronellol complex is ideal for applications requiring fast release of a high amount of fragrance, whereas the CBM::GQ₂₀::SP-DS3-liposome/β-citronellol complex is more suitable for prolonged and controlled release of a lower amount of β-citronellol.