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Carbohydrate-Active Enzymes
Published in Jean-Luc Wertz, Magali Deleu, Séverine Coppée, Aurore Richel, Hemicelluloses and Lignin in Biorefineries, 2017
Jean-Luc Wertz, Magali Deleu, Séverine Coppée, Aurore Richel
A number of possible reaction mechanisms could be involved: the most common is a serine (S)–histidine (H)–aspartate (D) catalytic triad catalyzed deacetylation analogous to the action of classical lipase and serine proteases.81 A catalytic triad usually refers to the three amino acid residues that function together at the center of the active site of certain hydrolase and transferase enzymes.85 A common method for generating a nucleophilic residue for covalent catalysis is by using an acid–base–nucleophile triad. The residues form a charge-relay network to polarize and activate the nucleophile, which attacks the substrate, forming a covalent intermediate which is then hydrolyzed to regenerate free enzyme. Other mechanisms such as a Zn2+ catalyzed deacetylation might also be considered for some families.81,86
FRET Reporter Molecules for Identification of Enzyme Functions
Published in Grunwald Peter, Biocatalysis and Nanotechnology, 2017
Jing Mu, Hao Lun Cheong, Bengang Xing
Serine (Ser) proteases are a family of endopeptidase, which is identified by the nucleophilic serine residue located at its enzymatic site. They are one of the largest proteases families, where they contributed to more than one third of all known proteolytic enzymes. Serine protease can be classified into 13 clans and 40 families (Page et al., 2008). Generically, they are divided into the various clans based on their catalytic mechanism and common ancestry shown in Table 13.1. Typically, the catalytic site of the serine proteases is dependent on the catalytic triad of aspartate (asp), histidine (his) and serine.
Microbial Mediated Biodegradation of Plastic Waste
Published in Amitava Rakshit, Manoj Parihar, Binoy Sarkar, Harikesh B. Singh, Leonardo Fernandes Fraceto, Bioremediation Science From Theory to Practice, 2021
Rajendra Prasad Meena, Sourav Ghosh, Surendra Singh Jatav, Manoj Kumar Chitara, Dinesh Jinger, Kamini Gautam, Hanuman Ram, Hanuman Singh Jatav, Kiran Rana, Surajyoti Pradhan, Manoj Parihar
The hydrolytic reaction is first initiated by class of enzymes known as ‘hydrolase’ comprising cutinase, phosphatase, laccase, esterase, lipase, glycosidase and many more (Bano et al. 2017). These enzymes have a characteristic a/0-hydrolase fold and the catalytic triad is comprised of a serine, a histidine and an aspartate residue (Wei et al. 2014). They can also comprise numerous disulfide bonds produced by cysteine residues, which help in thermal stability and specific binding to polymers such as PET.
α-Chymotrypsin-catalyzed synthesis of 2-substituted benzimidazole through retro-Claisen reaction
Published in Green Chemistry Letters and Reviews, 2018
Lian-Sheng Liu, Zong-Bo Xie, Can Zhang, Lei-Han Fu, Hai-Bo Zhu, Zhang-Gao Le
α-Chymotrypsin belongs to the family of serine proteases and is a polypeptide chain consisting of 245 amino acids; His-57, Asp-102, and Ser-195 constitute the catalytic triad (42–44). Combining this information and our part work (45), we purpose a plausible mechanism, as illustrated in Scheme 1. Initially, nucleophilic addition occurs to form intermediate imino ester A, in which the proton from the amido group of o-phenylenediamine may be abstracted by His 57 and the carbonyl of the ketone is effectively activated by Ser-195 (46,47). Subsequently, A undergoes cyclization to form aminal B along with the removal of water. In the presence of a His-57, the corresponding benzimidazole is produced by retro-Claisen reaction, along with regeneration of α-chymotrypsin to complete the catalytic cycle.
Atlantic Forest’s and Caatinga’s semiarid soils and their potential as a source for halothermotolerant actinomycetes and proteolytic enzymes
Published in Environmental Technology, 2023
Marghuel A. Vieira Silveira, Saara M. Batista dos Santos, Débora Noma Okamoto, Itamar Soares de Melo, Maria A. Juliano, Jair Ribeiro Chagas, Suzan P. Vasconcellos
The catalytic mechanism of serine proteases consists in the nucleophilic attack of the hydroxyl group of the serine residue to the peptide bond. Serine proteases present in their active site, a catalytic triad that, generally, comprises the amino acids H, S and A; however, different classes of serine may also present other proton donors, combined with the serine residue at the active site, as two H molecules, one H and one G molecule, just a L residue, among others [61,63]. Moreover, it is believed that representative serine proteases, such as trypsin and chymotrypsin, display preference for residues from R, Y and F [38] which corroborates the findings in the present study.