Serine-like proteases

Finally, serine protease from parasites and pathogens can mimic the biological roles of proteases in normal cells. Release of protease from parasites and pathogens can activate cells and produce an inflammatory response. Many pathogens and parasites contain cathepsins and elastases along with many of other serine or serine-like proteases like Streptomyces griseus A or B and a-lytic protease that lead to the invasion of abnormal cells and tissue... 

All the isozymes have a lot of overlapping identical residues and some regions of the sequences show similar characteristics to serine-like proteases, such as elastase and coagulation factor IX. The N-terminal sequences of F-III-1 and -III-2 are identical, and so are those of F-I-l and F-I-2, respectively. So far, several complete reading frames (amino acid sequences) of the isozymes, F-III-1 and -III-2 (L. rubellus) [24,28], EFE... 

EFEs are inhibited by a number of inhibitors, such as diisopropyl fluorophosphase (DFP) [24], soybean trypsin inhibitor (SBTI) [12,24], aprotinin [12,24], 1,6-hexamethylendiamine (HD) [49] and a2-macroglobulin (a2M) [50], etc. Nakajima et al. investigated some of the inhibitors when H-Z)-Phe-Pip-Arg-pNA is used as the substrate, as shown in Table (6). [24], DFP completely inhibits the activity of all the isozymes (pH 7.2) at room temperature. F-III-1 and F-II are strongly inhibited by SBTI and aprotinin, but F-I-0, -1-1 and -1-2 are partially inhibited. Nevertheless, Tosyl-phenylalanyl chloromethylketose (TPCK), tosyl-lysyl-chloromethylketose (TLCK), s-amino caproic acid (s-ACAk, elastatinal, EDTA and various metal ions, such as Fe2+, Cu2+ and Mnw cannot be detected to affect the activity under the conditions [24], On the basis of the specificity of substrates and inhibitors, EFE isomers are again exhibited the characteristics of alkaline serine-like proteases. 

Chymase (mast cell protease type II), a chymotrypsin-like protease, is a serine protease found in mucosal mast cells, which catalyzes the conversion of angiotensin I to angiotensin II and of big endothelin 1 (ET1) to ET1 (1-31). 

Bromomethyl-3,4-dibromo-3,4-dihydrocoumarin 1 (Fig. 11.4) and its chloro-methylated analogue 2b rapidly and progressively inactivate a-chymotrypsin and also the activities of a series of trypsin-like proteases. A benzyl substituent characteristic of good substrates of a-chymotrypsin was introduced at the 3-position to make inhibition more selective. This substituted dihydrocoumarin 3 irreversibly inhibited a-chymotrypsin and other proteases. These functionalized six-membered aromatic lactones, and their five- and seven-membered counterparts, 3//-benzofuran-2-ones 2a26 and 4,5-dihydro-3//-benzo[b]oxepin-2-ones 2c,27 were the first efficient suicide inhibitors of serine proteases. Their postulated mechanism of action is shown in Scheme 11.2. 

Many secreted proteins, as well as smaller peptide hormones, are acted upon in the endoplasmic reticulum by tryptases and other serine proteases. They often cut between pairs of basic residues such as KK, KR, or RR.214-216 A substilisin-like protease cleaves adjacent to methionine.217 Other classes of proteases (e.g., zinc-dependent carboxypeptidases) also participate in this processing. Serine carboxypeptidases are involved in processing human prohormones.218 Among the serine carboxypeptidases of known structure is one from wheat219 and carboxypeptidase Y, a vacuolar enzyme from yeast.220 Like the pancreatic metallocarboxypeptidases discussed in Section 4, these enzymes remove one amino acid at a time, a property that has made carboxypeptidases valuable reagents for determination of amino acid sequences. Carboxypeptidases may also be used for modification of proteins by removal of one or a few amino acids from the ends. 

The mammalian serine proteases appear to represent a classic case of divergent evolution. All were presumably derived from a common ancestral serine protease.23 Proteins derived from a common ancestor are said to be homologous. Some nonmammalian serine proteases are 20 to 50% identical in sequence with their mammalian counterparts. The crystal structure of the elastase-like protease from Streptomyces griseus has two-thirds of the residues in a conformation similar to those in the mammalian enzymes, despite having only 186 amino acids in its sequence, compared with 245 in a-chymotrypsin. The bacterial enzymes and the pancreatic ones have probably evolved from a common precursor. 

Pei et al. (2000) purified MAP-21, a further cuticle-degrading serine protease from M. anisopliae. Fungal cultures were induced by minimal medium supplemented with Cicada exuviae, colloidal chitin, shrimp cuticle, maggot cuticle, horsefly cuticle and silkworm Chrysalis cuticle. The recognition site of the protease occurred to be Arg. Studies with different protease inhibitors have revealed that MAP-21 is a trypsin-like protease. 

Figure 2 Bacillus subtiHs S2P-like protease SpolVFB and sporulation. When the mother cell engulfs the forespore, a signaling pathway that involves the transcription factor is initiated in the forespore that triggers the synthesis of the IVB serine protease. This protease degrades SpolVFA, which along with BofA serves to inhibit SpolVFB. With the inhibition of the S2P-like protease released, SpolVFB cleaves pro-c, which allows this transcription factor to signal in the mother cell for more factors needed for spore maturation.

Many secreted proteins, as well as smaller pephde hormones, are acted upon in fhe endoplasmic reticulum by frypfases and other serine proteases. They often cut between pairs of basic residues such as KK, KR, or A substilisin-like protease cleaves... 

Komatsu, N., Oda, T. and Muramatsu, T. (1998) Involvement of both caspase-like proteases and serine proteases in apoptotic cell death induced by ricin, modeccin, diphtheria toxin, and pseudomonas toxin. J Biochem (Tokyo), 124, 1038-1044. 

Serine-like proteinases are predominant in lepidopteran larvae [26]. It has been shown that different serine Pis are able to inactivate lepidopteran proteases and to cause deleterious effects on development and growth when incorporated into artificial diets [reviewed in 23, 25]. The first constitutive expression of a PI in a plant was reported by Hilder et al. 

Neutrophils also contain several cationic serine proteases (5). The enzyme, elastase, is particularly abundant The amount of elastase contained in the granules of a single neutrophil is in excess of one picogram (4) Several groups have used specific inhibitors as well as antisera to demonstrate that elastase or an elastase-like protease is abundant in chronic wound fluids (13,22-24). Mean levels of elastase activity is approximately 12-fold higher in fluids of chronic dermal ulcers compared to surgical... 

Serine proteases like chymotrypsiii are susceptible to inhibition by organic fluorophospbates, such as diisopropyljluorophosphate (DIFP, Figure 16.23). DIFP... 

Furin, also known as paired basic amino-acid-cleaving enzyme (PACE), is a membrane bound subtilisin-like serine protease of the irons Golgi compartment. It is ubiquitously expressed and mediates processing of many protein precursors at Arg-X-Lys/Arg-Arg sites. 

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