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Role of Engineered Proteins as Therapeutic Formulations
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Khushboo Gulati, Krishna Mohan Poluri
Cystine knot mini proteins (Knottins) are 30–50-amino-acid-long small proteins comprising a canonical cysteine knot. Structurally, knottins contain three antiparallel β-strands and are stabilized by three disulfide bonds arranged in a unique fashion. These bonds are formed between cys1 to cys 4, cys2 to cys5, and cys3 to cys6. The disulfide bond between cys3 to cys6 crosses a macrocycle formed by other two disulfide bonds and a backbone peptide bond. Together, these bonds form a cystine knot structure. Such a structure is responsible for higher thermal, chemical, and proteolytic stability of knottins. Cyclotides are a class of cystine knot proteins that undergo head to tail cyclization due to the presence of an extra loop in their structural architecture. Both knottins and cyclotides serve as promising candidates for potential therapeutic applications. External loops of both knottins and cyclotides make them amenable to various amino acid substitutions and also to the addition of various amino acids, rendering them structurally stable (Moore et al., 2012).
A secretory system for extracellular production of spider neurotoxin huwentoxin-I in Escherichia coli
Published in Preparative Biochemistry & Biotechnology, 2022
Changjun Liu, Qing Yan, Ke Yi, Tianhao Hu, Jianjie Wang, Zheyang Zhang, Huimin Li, Yutao Luo, Dongyi Zhang, Er Meng
In order to adapt to the environment, various venomous animals developed special organs, namely venom glands, for the production and injection of venoms to aid in prey capture and fight against predators. The most abundant animal toxins in animal venoms are a series of short bioactive peptides, principally stabilized by single or multiple disulfide bonds. For cysteine-rich peptides, disulfide bonds as an important post-translational modification are crucial for folding and maintaining three-dimensional structures and topological orientation.[37] The cysteine-rich peptides were usually stabilized by different disulfide bonds with different disulfide bridge patterns, such as inhibitory cystine knot (ICK) motif, disulfide-directed hairpin (DDH) motif, Kunitz type motif, and so on.[38].