Trypsin family

The serine proteases are the most extensively studied class of enzymes. These enzymes are characterized by the presence of a unique serine amino acid. Two major evolutionary families are presented in this class. The bacterial protease subtilisin and the trypsin family, which includes the enzymes trypsin, chymotrypsin, elastase as well as thrombin, plasmin, and others involved in a diverse range of cellular functions including digestion, blood clotting, hormone production, and complement activation. The trypsin family catalyzes the reaction ... 

Trifluoromethyl ketones are also powerful inhibitors of proteases of the trypsin family (trypsin, thrombin, enzymes of blood coagulation). " ... 

RNase can be completely denatured by boiling or by treatment with chaotropic agents (e.g., urea), yet can refold to its fully active form on cooling or removal of the denaturant. By contrast, when enzymes of the trypsin family and carboxypeptidase A are denatured, they do not regain full activity on renaturation. What aspects of trypsin and carboxypeptidase A structure preclude their renaturation to the fully active form ... 

Renaturation of denatured protein is dictated by the primary structure of the protein. The trypsin family of enzymes and carboxypeptidase A are synthesized as proenzymes that are proteolytically activated. The proteolyzed, active enzymes have primary structures different from the gene product and are not active upon renaturation. In addition, zinc is a cofactor required for carboxypeptidase A activity. 

Bikunin (Bik), a peptide excreted in the urine, is one of the primary inhibitors of the trypsin family of serine proteases. This peptide plays a key role in inflammation and innate immunity because of its two Kunitz-type binding domains [1, 2], Bik suppresses proteolytic activity in a variety of tissues and can also exert localized anti-inflammatory effect [3-5], Inflammation is an important indicator of infection, cancer, and tissue injury in acute and chronic states. In acute inflammation, fluids and plasma components accumulate in the affected tissues due to vascular dilation. Subsequent activation of platelets and increased presence of immune cells occur during repair. Long-standing inflammation may be present before the disorder is identified. Due to its inhibitory role and potential use as an early marker of inflammation, we will review the synthesis, structure, pathophysiology of Bik as well as the various approaches for its measurement in this chapter. 

Serine protease (trypsin family) released during inflammation... 

The trypsin family of serine proteases includes over 80 well-characterized enzymes having a minimum sequence homology of >21%. Two amino acid residues are absolutely conserved (Cysl82, Glyl96) within their active sites [26,27]. These proteases have similar catalytic mechanisms that lead to hydrolysis of ester and amide bonds. This occurs via an acyl transfer mechanism that utilizes proton donation by histidine to the newly formed alcohol or amine group, dissociation and formation of a covalent acyl-enzyme complex. 

The trypsin family of proteases plays a role in acute and chronic pancreatitis, as well as leads to its ultimate destruction [4, 105]. In pancreatitis, active exocrine enzymes are prematurely released inside the pancreatic duct. Various factors can contribute to the development of acute pancreatitis. Trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase are inactive proforms of proteolytic enzymes produced by the pancreatic acinar cells. Following secretion these enzymes are activated in a cascade that converts trypsinogen to trypsin in the duodenum and/or small intestine. 

Pan Z, Jeffery DA, Chehade K, Beltman J, Clark JM, Grothaus P, Bogyo M, Baruch A. Development of activity-based probes for trypsin-family serine proteases. Bioorg. Med. Chem. Lett. 2006 16 2882-2885. 

The first principle of enzyme inhibitor design is Use aU the available information . This information can be biological, functional, structural, chemical, or theoretical. There is such an immense amount of biological information on thrombin that it cannot be surveyed here we focus on thrombin as a serine protease of the trypsin family and take fibrinogen to be its primary substrate. A convenient way to look at the information available is from the more general to the very specific. For thrombin, we may take four levels the general catalytic mechanism the particular substrate types processed the structure of the protein and, often forgotten, the flexibihty of the protein required to achieve this function. 

The structure of the solvent around biological macromolecules has been reviewed in detail by Mattos and Ringe ]47]. Serine proteases of the trypsin family have 21 conserved buried water molecules, as first reported by Sreenivasan and Axelsen [48], These may be regarded as integral to the protein structure, and it... 

The amino acid sequences of the enzyme showed that homology with the trypsin family of serine proteases occurs only in the immediate vicinity of the acitve site... 

Proteases of the trypsin family have recently been applied in the synthesis of peptides that self-assemble to nanofibrous structures and for preparing biomaterials. An example is the chymotrypsin-catalyzed polymerization of the amphiphilic peptide Lys-Leu-OEt to an alternating oligomer that forms a hydrogel [8]. Furthermore, ch3unotrypsin was used for the synthesis of poly-L-cysteine, a material for the selective chelation of SH-reactive metal ions. A high yield (80%) was obtained under mild reaction conditions [54]. 

Chymotrypsin and V8 peptidase, members of the trypsin family of serine proteases, as well as an engineered trypsin variant (D189K/K60E), were employed for the N-terminal introduction of 2-aminobenzoyl- and 3-(4-hydroxy-phenyl)-propionyl groups, and biotin in the form of substrate mimetics into peptides [115]. 

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