Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Decorsin is a 39-residue polypeptide chain, crosslinked by three disulfide bridges, that strongly inhibits platelet aggregation. We report the chemical synthesis and characterization of analogs of decorsin with the aim of investigating the role of proline residues in protein structure, stability and biological activity. Decorsin analogs have been synthesized in which one (P23A and P24A decorsin) or two (P23,24A decorsin) proline residues have been substituted by alanine. The crude synthetic polypeptides were purified by reversed-phase HPLC in their reduced form and allowed to refold oxidatively to their disulfide-crosslinked species. The homogeneity of the synthetic mini-proteins, and also the correct pairing of the three disulfide bridges, were established by a number of analytical criteria, including fingerprinting analysis of the refolded synthetic analogs by using thermolysin and proteinase K as proteolytic enzymes. Replacement of proline by alanine results in a significant and cumulative decrease of the high thermal stability (Tm 74 degrees C) of native decorsin. The mono-substituted analogs display a Tm of 66-67 degrees C, while the double-substituted analog a Tm of 50 degrees C. On the other hand, the overall secondary and tertiary structures were not affected by the Pro-->Ala exchanges, as judged from circular dichroism measurements. Platelet aggregation assays established that the proline substitutions do not impair significantly the biological activity of decorsin. The results of this study clearly indicate that proline residues contribute significantly to the protein thermal stability. Our results are in line with the 'proline rule', previously advanced for explaining the unusual thermal stability of thermophilic enzymes, which usually show an enhanced content of proline residues with respect to their mesophilic counterparts.
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PMID:Chemical synthesis of the RGD-protein decorsin: Pro-->Ala replacement reduces protein thermostability. 1615 18

The most abundant alpha-amylase (EC 3.2.1.1) in shoots and cotyledons from pea (Pisum sativum L.) seedlings was purified 6700-and 850-fold, respectively, utilizing affinity (amylose and cycloheptaamylose) and gel filtration chromatography and ultrafiltration. This alpha-amylase contributed at least 79 and 15% of the total amylolytic activity in seedling cotyledons and shoots, respectively. The enzyme was identified as an alpha-amylase by polarimetry, substrate specificity, and end product analyses. The purified alpha-amylases from shoots and cotyledons appear identical. Both are 43.5 kilodalton monomers with pls of 4.5, broad pH activity optima from 5.5 to 6.5, and nearly identical substrate specificities. They produce identical one-dimensional peptide fingerprints following partial proteolysis in the presence of SDS. Calcium is required for activity and thermal stability of this amylase. The enzyme cannot attack maltodextrins with degrees of polymerization below that of maltotetraose, and hydrolysis of intact starch granules was detected only after prolonged incubation. It best utilizes soluble starch as substrate. Glucose and maltose are the major end products of the enzyme with amylose as substrate. This alpha-amylase appears to be secreted, in that it is at least partially localized in the apoplast of shoots. The native enzyme exhibits a high degree of resistance to degradation by proteinase K, trypsin/chymostrypsin, thermolysin, and Staphylococcus aureus V8 protease. It does not appear to be a high-mannose-type glycoprotein. Common cell wall constituents (e.g. beta-glucan) are not substrates of the enzyme. A very low amount of this alpha-amylase appears to be associated with chloroplasts; however, it is unclear whether this activity is contamination or alpha-amylase which is integrally associated with the chloroplast.
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PMID:Characterization of alpha-Amylase from Shoots and Cotyledons of Pea (Pisum sativum L.) Seedlings. 1666 84

The formation of local structure, in short peptides has been probed by examining cleavage patterns and rates of proteolysis of designed sequences with a high tendency to form beta-hairpin structures. Three model sequences which bear fluorescence donor and acceptor groups have been investigated: [see text]. Fluorescence resonance energy transfer (FRET) provides a convenient probe for peptide cleavage. MALDI mass spectrometry has been used to probe sites of cleavage and CD spectroscopy to access the overall backbone conformation using analog sequences, which lack strongly absorbing donor and acceptor groups. The proteases trypsin, subtilisin, collagenase, elastase, proteinase K and thermolysin were used for proteolysis and the rates of cleavage determined. Peptide 3 is the most susceptible to cleavage by all the enzymes except thermolysin, which cleaves all three peptides at comparable rates. Peptides 1 and 2 are completely resistant to the action of trypsin, suggesting that beta-turn formation acts as a deterrent to proteolytic cleavage.
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PMID:Structure formation in short designed peptides probed by proteolytic cleavage. 1680 Aug

Alpha-synuclein (alpha-syn) is a "natively unfolded" protein constituting the major component of intracellular inclusions in several neurodegenerative disorders. Here, we describe proteolysis experiments conducted on human alpha-syn in the presence of SDS micelles. Our aim was to unravel molecular features of micelle-bound alpha-syn using the limited proteolysis approach. The nonspecific proteases thermolysin and proteinase K, as well as the Glu-specific V8-protease, were used as proteolytic probes. While alpha-syn at neutral pH is easily degraded to a variety of relatively small fragments, in the presence of 10 mM SDS the proteolysis of the protein is rather selective. Complementary fragments 1-111 and 112-140, 1-113 and 114-140, and 1-123 and 124-140 are obtained when thermolysin, proteinase K, and V8 protease, respectively, are used. These results are in line with a conformational model of alpha-syn in which it acquires a folded helical structure in the N-terminal region in its membrane-bound state. At the same time, they indicate that the C-terminal portion of the molecule is rather rigid, as seen in its relative resistance to extensive proteolytic degradation. It is likely that, under the specific experimental conditions of proteolysis in the presence of SDS, the negatively charged C-terminal region can be rigidified by binding a calcium ion, as shown before with intact alpha-syn. In this study, some evidence of calcium binding properties of isolated C-terminal fragments 112-140, 114-140, and 124-140 was obtained by mass spectrometry measurements, since molecular masses for calcium-loaded fragments were obtained. Our results indicate that the C-terminal portion of the membrane-bound alpha-syn is quite rigid and structured, at variance from current models of the membrane-bound protein deduced mostly from NMR. Considering that the aggregation process of alpha-syn is modulated by its C-terminal tail, the results of this study may provide useful insights into the behavior of alpha-syn in a membrane-mimetic environment.
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PMID:Conformational properties of the SDS-bound state of alpha-synuclein probed by limited proteolysis: unexpected rigidity of the acidic C-terminal tail. 1698 12

The molecular diagnosis of prion diseases almost always involves the use of a protease to distinguish PrPC from PrPSc and invariably the protease of choice is proteinase K. Here, we have applied the protease thermolysin to the diagnosis of animal prion diseases. This thermostable protease cleaves at the hydrophobic residues Leu, Ile, Phe, Val, Ala, and Met, residues that are absent from the protease accessible aminoterminal region of PrPSc. Therefore, although thermolysin readily digests PrPC into small protein fragments, full-length PrPSc is resistant to such proteolysis. This contrasts with proteinase K digestion where an aminoterminally truncated PrPSc species is produced, PrP27-30. Thermolysin was used in the diagnosis of ovine scrapie and bovine spongiform encephalopathy and produced comparable assay sensitivity to assays using proteinase K digestion. Furthermore, we demonstrated the concentration of thermolysin-resistant PrPSc using immobilized metal-affinity chromatography. The use of thermolysin to reveal a full-length PrPSc has application for the development of novel immunodiagnostics by exploiting the wide range of commercially available immunoreagents and metal affinity matrices that bind the amino-terminal region of PrP. In addition, thermolysin provides a complementary tool to proteinase K to allow the study of the contribution of the amino-terminal domain of PrPSc to disease pathogenesis.
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PMID:Use of thermolysin in the diagnosis of prion diseases. 1743 82

Five serine proteinase inhibitors (Mirabilis jalapa trypsin inhibitors, MJTI I and II and Spinacia oleracea trypsin inhibitors, SOTI I, II, and III) from the garden four-o'clock (M. jalapa) and spinach (S. oleracea) seeds were isolated. The purification procedures included affinity chromatography on immobilized methylchymotrypsin in the presence of 5M NaCl, ion exchange chromatography and/or preparative electrophoresis, and finally RP-HPLC on a C-18 column. The inhibitors, crosslinked by three disulfide bridges, are built of 35 to 37 amino-acid residues. Their primary structures differ from those of known trypsin inhibitors, but showed significant similarity to the antimicrobial peptides isolated from the seeds of M. jalapa (MJ-AMP1, MJ-AMP2), Mesembryanthemum crystallinum (AMP1), and Phytolacca americana (AMP-2 and PAFP-S) and from the hemolymph of Acrocinus longimanus (Alo-1, 2 and 3). The association equilibrium constants (K(a)) with bovine beta-trypsin for the inhibitors from M. jalapa (MJTI I and II) and S. oleracea (SOTI I-III) were found to be about 10(7)M(-1). Fully active MJTI I and SOTI I were obtained by solid-phase peptide synthesis. The disulfide bridge pattern in both inhibitors (Cys1-Cys4, Cys2-Cys5 and Cys3-Cys6) was established after their digestion with thermolysin and proteinase K followed by the MALDI-TOF analysis.
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PMID:Trypsin inhibitors from the garden four o'clock (Mirabilis jalapa) and spinach (Spinacia oleracea) seeds: isolation, characterization and chemical synthesis. 1748 78

A synthetic collagenase substrate containing the internal peptide sequence--Gly-Gly-Pro-Leu-Gly-Pro-Pro-Gly-Pro--has been synthesized, with an N-terminus 4-((4-(dimethylamino)phenyl)azo)-benzoyl (DABCYL) group and C-terminus 5-[2-(acetamido)ethylamino] naphthalene-1-sulfonic acid (AEDANS) moiety resulting in internal quenching of AEDANS fluorescence. Peptide bond hydrolysis results in a large increase in fluorescence at 490 nm upon excitation at 336 nm. The substrate is cleaved exclusively by Clostridium histolyticum collagenase and is completely resistant to attack by proteases like thermolysin, proteinase K, and trypsin. K(m) and V(max) values for substrate hydrolysis by collagenase have been determined, establishing the peptide as one of the best binding substrates for the enzyme. MALDI mass spectrometry using a derivative of the substrate establishes that the sites of cleavage lie within the collagen like domain. The CD spectrum of an analog peptide lacking the donor and acceptor groups reveals spectral features that are reminiscent of weak polyproline structures.
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PMID:An internally quenched fluorescent substrate for collagenase. 1826 Jan 38

Disease-related PrP(Sc) [pathogenic PrP (prion protein)] is classically distinguished from its normal cellular precursor, PrP(C)(cellular PrP) by its detergent insolubility and partial resistance to proteolysis. Although molecular diagnosis of prion disease has historically relied upon detection of protease-resistant fragments of PrP(Sc) using PK (proteinase K), it is now apparent that a substantial fraction of disease-related PrP is destroyed by this protease. Recently, thermolysin has been identified as a complementary tool to PK, permitting isolation of PrP(Sc) in its full-length form. In the present study, we show that thermolysin can degrade PrP(C) while preserving both PK-sensitive and PK-resistant isoforms of disease-related PrP in both rodent and human prion strains. For mouse RML (Rocky Mountain Laboratory) prions, the majority of PK-sensitive disease-related PrP isoforms do not appear to contribute significantly to infectivity. In vCJD (variant Creutzfeldt-Jakob disease), the human counterpart of BSE (bovine spongiform encephalopathy), up to 90% of total PrP present in the brain resists degradation with thermolysin, whereas only approximately 15% of this material resists digestion by PK. Detection of PK-sensitive isoforms of disease-related PrP using thermolysin should be useful for improving diagnostic sensitivity in human prion diseases.
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PMID:Detection and characterization of proteinase K-sensitive disease-related prion protein with thermolysin. 1868 6

The cerebral prion protein (PrP) isolated in the absence of proteinase K digestion, from ruminants prion sources transmitted to ovine transgenic mice, was studied by Western blot analysis. A C2 PrP fragment, showing strain-specific cleavages, similar to those observed after proteinase K or thermolysin digestion, accumulated in the brain. 'CH1641-like' scrapie was characterized by the unique accumulation of a more C-terminally cleaved PrP fragment (CTF14). A similar, protease-resistant, PrP product was observed after proteinase K or thermolysin digestion. Whereas classical BSE appeared highly resistant to thermolysin digestion, CH1641 and 'CH1641-like' natural isolates did not show any remarkable feature regarding resistance to thermolysin. Thus, the molecular strain-specific features in the brain of transmissible spongiform encephalopathy infected mice essentially reflect the PrP proteolytic processing occurring in vivo.
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PMID:Strain-specific proteolytic processing of the prion protein in prion diseases of ruminants transmitted in ovine transgenic mice. 1982 61

N,N'-diBoc-dityrosine (DBDY), which was synthesized by the oxidative C-C coupling of 2 N-Boc-L-tyrosine molecules, was conjugated with two isoniazid (INH) molecules. Due to the quenching effect of INH, DBDY-(INH)(2) lacks the fluorescence of DBDY. As such, it was tested for use in the detection of proteases by measuring fluorescence recovery. In this study, serine proteases (chymotrypsin, trypsin, subtilisin, and proteinase K), metalloproteases (thermolysin and carboxypeptidase A, dispase, and collagenase), aspartic proteases (pepsin and aspergillopepsin) and cysteine proteases (papain and chymopapain) were chosen. Reported optimum assay conditions were chosen for each enzyme. Only papain and chymopapain catalyzed the hydrolysis of DBDY-(INH)(2) and led to fluorescence recovery, possibly due to their extensive binding sites and the INH-mediated inhibition of metalloproteases and aspartic proteases.
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PMID:A dityrosine-based substrate for a protease assay: application for the selective assessment of papain and chymopapain activity. 2244 80


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