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Formulation of Protein- and Peptide-Based Parenteral Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Gaozhong Zhu, Pierre O. Souillac
Non-reducible aggregates through non-disulfide linkages have also been reported. The reactions involving these covalent linkages include (i) oxidation-induced reactions through Trp or Tyr linkage (25); (ii) reaction through transamidation, whereby an amino group of amino acids (e.g., lysine residue or N-terminal of a protein) in one molecule forms an isopeptide bond with the carbonyl group of either Asn or Gln in another molecule [examples are insulin (26) and lyophilized ribonuclease A (27)]; and (iii) reaction through a reactive dehydroalanine generated from β-elimination at alkaline pH, which forms non-reducible cross linkages with other amino acids such as Tyr, Lys, His, Arg, and Cys, as described in the “β-Elimination” section.
Arsenals of Pharmacotherapeutically Active Proteins and Peptides: Old Wine in a New Bottle
Published in Debarshi Kar Mahapatra, Swati Gokul Talele, Tatiana G. Volova, A. K. Haghi, Biologically Active Natural Products, 2020
The isopeptide bond is a bond formed between amino groups of lysine residue of a protein with the carboxyl group of another protein molecule. The isopeptide bond is formed when the protein is tagged for degradation with ubiquitin. The ε amino group of lysine is linked to the carboxy-terminal of the ubiquitin. Thus, the ubiquitinylated protein is degraded by proteasome.
New approaches towards the discovery and evaluation of bioactive peptides from natural resources
Published in Critical Reviews in Environmental Science and Technology, 2020
Nam Joo Kang, Hyeon-Su Jin, Sung-Eun Lee, Hyun Jung Kim, Hong Koh, Dong-Woo Lee
Advances in genome sequencing technology have enabled us to develop a broad repertoire of proteolytic biocatalysts from metagenomic samples, including uncultured microorganisms. As an alternative to conventional protease-screening approaches, metagenomic data enable us to mine putative genes encoding proteases and predict their catalytic mechanisms and functions using the MEROPS database (http://www.ebi.ac.uk/merops/), which contains all peptidases found in humans and their homologs in other organisms, including many pseudogenes and protease-related sequences within the human genome (Figure 2) (Rawlings et al., 2018). Proteases are hydrolytic enzymes responsible for the cleavage of α-peptide bonds between naturally occurring amino acids. In addition, some proteases, such as γ-glutamyl hydrolase, glutamate carboxypeptidase, and γ-glutamyl transferases, can hydrolyze isopeptide bonds or even synthesize peptide bonds. Moreover, beyond the evolutionary diversity of proteases (López-Otín & Bond, 2008), which we will not discuss in this review, the recent availability of prokaryotic genome sequences has allowed us to identify unique proteases distinct from human counterparts, leading in turn to the identification of a variety of new BPs. For example, unusual proteases such as collagenases and keratinases exhibit an exquisite specificity towards a unique peptide bond in animal-derived proteins rich in non-polar amino acids, e.g. fish collagen and poultry keratin. In contrast to proteinase K, which is relatively nonspecific, several proteinases derived from extremophiles have unique degradation patterns that yield novel BPs (H. Jang et al., 2002; Jin et al., 2017).