scholarly journals Production, purification and characterization of the catalytic domain of glucoamylase from Aspergillus niger

1993 ◽  
Vol 292 (1) ◽  
pp. 197-202 ◽  
Author(s):  
B Stoffer ◽  
T P Frandsen ◽  
P K Busk ◽  
P Schneider ◽  
I Svendsen ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Catalytic Domain ◽  
Limited Proteolysis ◽  
Exchange Chromatography ◽  
High Yield ◽  
Amino Acid Residues ◽  
Single Chain ◽  
Subtilisin Carlsberg ◽  
A Minor

The catalytic domain of glucoamylases G1 and G2 from Aspergillus niger is produced in vitro in high yield by limited proteolysis using either subtilisin Novo or subtilisin Carlsberg. Purification by affinity chromatography on an acarbose-Sepharose column followed by ion-exchange chromatography on HiLoad Q-Sepharose leads to separation of a number of structurally closely related forms of domain. The cleavage occurs primarily between Val-470 and Ala-471 as indicated by C-terminal sequencing, whereas the N-terminus is intact. Subtilisin Carlsberg, in addition, produces a type of domain which is hydrolysed before Ser-444, an O-glycosylated residue. This leaves the fragment Ser-444-Val-470 disulphide-bonded to the large N-terminal part of the catalytic domain. Subtilisin Novo, in contrast, tends to yield a minor fraction of forms extending approx. 30-40 amino-acid residues beyond Val-470. The thermostability is essentially the same for the single-chain catalytic domain and the original glucoamylases G1 and G2, whereas the catalytic domain cut between Ser-443 and Ser-444 is less thermostable. For both types of domain the kinetic parameters, Km and kcat., for hydrolysis of maltose are very close to the values found for glucoamylases G1 and G2.

Structural basis of cofactor-mediated stabilization and substrate recognition of the α-tubulin acetyltransferase αTAT1

2015 ◽  
Vol 467 (1) ◽  
pp. 103-113 ◽  
Author(s):  
Satoru Yuzawa ◽  
Sachiko Kamakura ◽  
Junya Hayase ◽  
Hideki Sumimoto
Keyword(s):  
Catalytic Domain ◽  
Substrate Recognition ◽  
Structural Basis ◽  
Stable Complex ◽  
Amino Acid Residues ◽  
Substrate Selection ◽  
Post Translational Modification ◽  
Acetyl Group

The functions of microtubules are controlled in part by tubulin post-translational modification including acetylation of Lys40 in α-tubulin. αTAT1 (α-tubulin acetyltransferase 1), an enzyme evolutionarily conserved among eukaryotes, has recently been identified as the major α-tubulin Lys40 acetyltransferase, in which AcCoA (acetyl-CoA) serves as an acetyl group donor. The regulation and substrate recognition of this enzyme, however, have not been fully understood. In the present study, we show that AcCoA and CoA each form a stable complex with human αTAT1 to maintain the protein integrity both in vivo and in vitro. The invariant residues Arg132 and Ser160 in αTAT1 participate in the stable interaction not only with AcCoA but also with CoA, which is supported by analysis of the present crystal structures of the αTAT1 catalytic domain in complex with CoA. Alanine substitution for Arg132 or Ser160 leads to a drastic misfolding of the isolated αTAT1 catalytic domain in the absence of CoA and AcCoA but not in the presence of excess amounts of either cofactor. A mutant αTAT1 carrying the R132A or S160A substitution is degraded much faster than the wild-type protein when expressed in mammalian Madin–Darby canine kidney cells. Furthermore, alanine-scanning experiments using Lys40-containing peptides reveal that α-tubulin Ser38 is crucial for substrate recognition of αTAT1, whereas Asp39, Ile42, the glycine stretch (amino acid residues 43–45) and Asp46 are also involved. The requirement for substrate selection is totally different from that in various histone acetyltransferases, which appears to be consistent with the inability of αTAT1 to acetylate histones.

scholarly journals Human extracellular superoxide dismutase is a tetramer composed of two disulphide-linked dimers: a simplified, high-yield purification of extracellular superoxide dismutase

1996 ◽  
Vol 317 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Tim D. OURY ◽  
James D. CRAPO ◽  
Zuzana VALNICKOVA ◽  
Jan J. ENGHILD
Keyword(s):  
Superoxide Dismutase ◽  
Limited Proteolysis ◽  
Exchange Chromatography ◽  
Disulphide Bond ◽  
High Yield ◽  
Human Aorta ◽  
Extracellular Superoxide Dismutase ◽  
Heparin Binding ◽  
Sod Activity ◽  
Native Page

Studies examining the biochemical characteristics and pharmacological properties of extracellular superoxide dismutase (EC SOD) have been severely limited because of difficulties in purifying the enzyme. Recently EC SOD was found to exist in high concentrations in the arteries of most mammals examined and it is the predominant form of SOD activity in many arteries. We now describe a three-step, high-yield protocol for the purification of EC SOD from human aorta. In the first step, the high affinity of EC SOD for heparin is utilized to obtain a fraction in which EC SOD constitutes roughly 13% of the total protein compared with only 0.3% of that of the starting material. In addition, over 80% of the original EC SOD activity present in the aortic homogenate was retained after the first step of purification. EC SOD was further purified using a combination of cation- and anion-exchange chromatography. The overall yield of EC SOD from this purification procedure was 46%, with over 4 mg of EC SOD obtained from 230 g of aorta. Purified EC SOD was found to exist predominantly as a homotetramer composed of two disulphide-linked dimers. However, EC SOD was also found to form larger multimers when analysed by native PAGE. It was shown by urea denaturation that the formation of multimers increased the thermodynamic stability of the protein. Limited proteolysis of EC SOD suggested that there is one interchain disulphide bond covalently linking two subunits. This disulphide bond involves cysteine-219 and appears to link the heparin-binding domains of the two subunits.

scholarly journals Long-chain polyphosphates impair SARS-CoV-2 infection and replication

2021 ◽  
Vol 14 (690) ◽  
pp. eabe5040
Author(s):  
Veronica Ferrucci ◽  
Dae-Young Kong ◽  
Fatemeh Asadzadeh ◽  
Laura Marrone ◽  
Angelo Boccia ◽  
...  
Keyword(s):  
Amino Acid ◽  
Limited Proteolysis ◽  
High Energy ◽  
Site Directed Mutagenesis ◽  
Linear Polymers ◽  
Amino Acid Residues ◽  
Human Nasal Epithelial Cells ◽  
Antiviral Activities ◽  
Long Chain

Inorganic polyphosphates (polyPs) are linear polymers composed of repeated phosphate (PO43−) units linked together by multiple high-energy phosphoanhydride bonds. In addition to being a source of energy, polyPs have cytoprotective and antiviral activities. Here, we investigated the antiviral activities of long-chain polyPs against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In molecular docking analyses, polyPs interacted with several conserved amino acid residues in angiotensin-converting enzyme 2 (ACE2), the host receptor that facilitates virus entry, and in viral RNA-dependent RNA polymerase (RdRp). ELISA and limited proteolysis assays using nano– LC-MS/MS mapped polyP120 binding to ACE2, and site-directed mutagenesis confirmed interactions between ACE2 and SARS-CoV-2 RdRp and identified the specific amino acid residues involved. PolyP120 enhanced the proteasomal degradation of both ACE2 and RdRp, thus impairing replication of the British B.1.1.7 SARS-CoV-2 variant. We thus tested polyPs for functional interactions with the virus in SARS-CoV-2–infected Vero E6 and Caco2 cells and in primary human nasal epithelial cells. Delivery of a nebulized form of polyP120 reduced the amounts of viral positive-sense genomic and subgenomic RNAs, of RNA transcripts encoding proinflammatory cytokines, and of viral structural proteins, thereby presenting SARS-CoV-2 infection in cells in vitro.

Isolation of FSH from bovine pituitary glands

1993 ◽  
Vol 137 (1) ◽  
pp. 59-68 ◽  
Author(s):  
J.-B. Wu ◽  
P. G. Stanton ◽  
D. M. Robertson ◽  
M. T. W. Hearn
Keyword(s):  
Amino Acid ◽  
Biological Activities ◽  
Gel Filtration ◽  
Exchange Chromatography ◽  
High Yield ◽  
Purification Procedure ◽  
In Vitro Bioassay ◽  
Α Subunit ◽  
Pituitary Glands

ABSTRACT An improved method is described for the isolation of FSH from bovine pituitary glands. The purification procedure consisted of an initial ammonium sulphate precipitation step followed by triazine-dye chromatography, immobilized metal affinity chromatography, high-performance anion-exchange chromatography and gel filtration. Three highly purified bovine FSH preparations (designated bFSH-A, -B and -C) were obtained, giving yields of approximately 5·7 mg FSH/kg bovine pituitary glands (wet weight), with specific radioreceptor activities for bFSH-A, -B and -C of 61, 25 and 29 units (NIH-FSH-S1)/mg protein respectively. The corresponding biological activities were 217 (bFSH-A), 62 (bFSH-B) and 86 (bFSH-C) units/mg, as measured by an FSH in-vitro bioassay. LH levels were found to be < 1% (w/w) as determined by an LH in-vitro bioassay. SDS-PAGE of these bFSH preparations under reducing conditions in 16% polyacrylamide gels showed two major silver-staining bands of apparent molecular masses 19·5 kDa and 15·8 kDa. Their amino acid compositions were in close agreement with the expected composition, based on the bFSH cDNA sequence and results reported by other investigators. N-terminal sequencing of the bFSH-A preparation yielded two major sequences consistent with α- and β-subunits, and a third minor (< 20%) sequence consistent with the α-subunit clipped at amino acid residue 6. It was concluded that the bFSH purification procedure reported here is a rapid method which produces bFSH in high yield and high purity, with radioreceptor and in-vitro specific activities comparable with those previously reported by other investigators. Journal of Endocrinology (1993) 137, 59–68

scholarly journals Purification of glutamate dehydrogenase from ox brain and liver. Evidence that commercially available preparations of the enzyme from ox liver have suffered proteolytic cleavage

1980 ◽  
Vol 191 (2) ◽  
pp. 605-611 ◽  
Author(s):  
A D McCarthy ◽  
J M Walker ◽  
K F Tipton
Keyword(s):  
Glutamate Dehydrogenase ◽  
Liver Enzyme ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Limited Proteolysis ◽  
Deae Cellulose ◽  
Exchange Chromatography ◽  
Amino Acid Residues ◽  
Commercial Preparation ◽  
Commercial Sources

1. A rapid procedure, involving ion-exchange chromatography on DEAE-cellulose and affinity chromatography on GTP-Sepharose, was used to purify glutamate dehydrogenase from ox brain and liver. 2. Preparations purified in this way differed from those of the ox liver enzyme that were obtained from commercial suppliers in their mobilities on polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. This difference appears to result from the occurrence of limited proteolysis during the preparation of the latter enzyme samples. 3. N-Terminal sequence analysis showed the presence of four amino acid residues in the enzyme prepared in this study that were not present in those obtained from the commercial sources and which have not been reported in previous studies on the sequence of the ox liver enzyme. 4. A preliminary examination of the enzyme prepared in this way indicated that the Michaelis constants for the substrates are similar to those obtained from the commercial preparation, but that the response to allosteric effectors was modified.

scholarly journals Localization of the rap1GAP catalytic domain and sites of phosphorylation by mutational analysis.

1992 ◽  
Vol 12 (10) ◽  
pp. 4634-4642 ◽  
Author(s):  
B Rubinfeld ◽  
W J Crosier ◽  
I Albert ◽  
L Conroy ◽  
R Clark ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Mutational Analysis ◽  
Point Mutations ◽  
Amino Terminus ◽  
Amino Acid Residues ◽  
Gtpase Activating Protein ◽  
Mutant Proteins ◽  
Carboxy Terminal

rap1GAP is a GTPase-activating protein that specifically stimulates the GTP hydrolytic rate of p21rap1. We have defined the catalytic domain of rap1GAP by constructing a series of cDNAs coding for mutant proteins progressively deleted at the amino- and carboxy-terminal ends. Analysis of the purified mutant proteins shows that of 663 amino acid residues, only amino acids 75 to 416 are necessary for full GAP activity. Further truncation at the amino terminus resulted in complete loss of catalytic activity, whereas removal of additional carboxy-terminal residues dramatically accelerated the degradation of the protein in vivo. The catalytic domain we have defined excludes the region of rap1GAP which undergoes phosphorylation on serine residues. We have further defined this phosphoacceptor region of rap1GAP by introducing point mutations at specific serine residues and comparing the phosphopeptide maps of the mutant proteins. Two of the sites of phosphorylation by cyclic AMP (cAMP)-dependent kinase were localized to serine residues 490 and 499, and one site of phosphorylation by p34cdc2 was localized to serine 484. In vivo, rap1GAP undergoes phosphorylation at four distinct sites, two of which appear to be identical to the sites phosphorylated by cAMP-dependent kinase in vitro.

AN IMPROVED METHODOLOGY FOR THE EXTRACTION AND PARTIAL PURIFICATION OF PORCINE HYPOTHALAMIC CORTICOTROPHIN RELEASING FACTOR

1980 ◽  
Vol 84 (2) ◽  
pp. 189-197 ◽  
Author(s):  
A. F. BRISTOW ◽  
D. MONTAGUE ◽  
D. SYNETOS ◽  
G. JENKINS ◽  
D. COCKAYNE ◽  
...  
Keyword(s):  
Large Scale ◽  
Cell System ◽  
Exchange Chromatography ◽  
High Yield ◽  
Partial Purification ◽  
Proteolytic Degradation ◽  
Minimal Effective Dose ◽  
Corticotrophin Releasing Factor ◽  
Subsequent Elution

In most previous reports material with corticotrophin releasing factor (CRF) activity has been obtained from hypothalami after extraction with dilute aqueous acid. Such conditions allow substantial proteolytic degradation. By adopting conditions designed to precipitate proteases and by using information on the nature of CRF gained from earlier studies, rapid large scale extraction and partial purification of porcine hypothalamic CRF in high yield was achieved. After extraction with 0·2 m-HCl: acetone (1: 1, v/v), centrifugation and ultrafiltration, considerable preliminary purification of the CRF activity was achieved by adsorption onto carboxymethylcellulose and subsequent elution at increased salt concentration. Following ion-exchange chromatography of the extract on carboxymethylcellulose, CRF activity was obtained in good yield (minimal effective dose of about 1–2 μg/ml) for ACTH release in an in-vitro CRF bioassay utilizing a coupled isolated pituitary cell–adrenal cell system. The data indicated that the previously reported heterogeneous corticotrophin releasing factors of low activity may be a consequence of proteolytic degradation.

Characterization of Domain Deletion and/or Duplication Mutants of a Recombinant Chimera of Tissue-Type Plasminogen Activator and Urokinase-Type Plasminogen Activator (rt-PA/u-PAI)

1990 ◽  
Vol 64 (01) ◽  
pp. 053-060 ◽  
Author(s):  
L Nelles ◽  
H R Lijnen ◽  
A Van Nuffelen ◽  
E Demarsin ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Catalytic Domain ◽  
Tissue Type ◽  
Clot Lysis ◽  
Single Chain ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Specific Activities

SummaryChimeric molecules comprising the A-chain of tissue-type plasminogen activator (t-PA) and the catalytic domain of urokinase-type plasminogen activator (u-PA) have intact enzymatic characteristics of u-PA, but only partial fibrin-binding properties of t-PA (Nelles et al., J Biol Chem 1987; 262: 10855–62). The following domain deletion and/or duplication mutants of such a t-PA/u-PA chimera were constructed, purified and charactertzed: rt-PA-ΔFE∇/u-PA, with deletion of the finger-like (F) and epidermal growth factor-like (E) domains, rt-PA-ΔK1∇K2/u-PA, with kringle 1 (K1) replaced by a second copy of kringle 2 (K2), and rt-PA-ΔFEK1∇K2/u-PA, with F and E domain deletions in rt-PAΔK1∇K2/u-PA.The specific activities on fibrin plates of the single-chain (sc) chimeras ranged between 68,000 IU/mg for rt-PA-ΔK1∇K2/scu-PA and 200,000 IU/mg for rt-PA-ΔFEK1∇K2/scu-PA, as compared to L20,000 IU/mg for rscu-PA. The specific activities of their plasmin-generated two-chain (tc) derivatives ranged between 120,000 IU/mg for rt-PA-ΔK1∇K2/tcu-PA and 240,000 IU/mg for rt-PA-ΔFEK1∇K2/tcu-PA, as compared to 100,000 IU/mg for rtcu-PA. All two-chain chimeras activated plasminogen following Michaelis-Menten kinetics, with catalytic efficiencies between 0.072 μM−1s−1 for rt-PA-ΔK1∇K2/tcu-pA and 0.081 pM−1 s−1 for rt-PA-ΔFEK1∇K2/tcu-PA, as compared to 0.088 μM−1 s−1 for rtcu-PA. CNBr-digested fibrinogen enhanced the initial rate of plasminogen activation by a factor 2.2 to 6.2, as compared to 4.9 for rtcu-PA. The fibrin-affinity of the chimeras decreased in the order rt-PA > rt-PA-ΔK1∇K2/u-PA > u-PA and that for lysine in the order rt-PA-ΔFEK1∇K2/u-PA > > t-PA/u-PA ⩽ st-PA > rt-PA-ΔFE/u-PA > u-PA. All single-chain plasminogen activators caused a time and concentration-dependent clot lysis in an in vitro plasma clot lysis system, with equi-effective doses (causin g 50% clot lysis in 2 h) ranging between 0.53 and 0.90 μg/ml, as compared to 1 .7 μg/ml for rscu-PA, and were associated with comparable residual fibrinogen levels of approximately 80%.Thus, substitution of K1 by a second copy of K2 in the chimeric protein t-PA/u-PA enhances the affinity for both fibrin and lysine significantly and improves the fibrinolytic potency in an in vitro clot lysis system marginally.

Localization of the rap1GAP catalytic domain and sites of phosphorylation by mutational analysis

1992 ◽  
Vol 12 (10) ◽  
pp. 4634-4642
Author(s):  
B Rubinfeld ◽  
W J Crosier ◽  
I Albert ◽  
L Conroy ◽  
R Clark ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Mutational Analysis ◽  
Point Mutations ◽  
Amino Terminus ◽  
Amino Acid Residues ◽  
Gtpase Activating Protein ◽  
Mutant Proteins ◽  
Carboxy Terminal

rap1GAP is a GTPase-activating protein that specifically stimulates the GTP hydrolytic rate of p21rap1. We have defined the catalytic domain of rap1GAP by constructing a series of cDNAs coding for mutant proteins progressively deleted at the amino- and carboxy-terminal ends. Analysis of the purified mutant proteins shows that of 663 amino acid residues, only amino acids 75 to 416 are necessary for full GAP activity. Further truncation at the amino terminus resulted in complete loss of catalytic activity, whereas removal of additional carboxy-terminal residues dramatically accelerated the degradation of the protein in vivo. The catalytic domain we have defined excludes the region of rap1GAP which undergoes phosphorylation on serine residues. We have further defined this phosphoacceptor region of rap1GAP by introducing point mutations at specific serine residues and comparing the phosphopeptide maps of the mutant proteins. Two of the sites of phosphorylation by cyclic AMP (cAMP)-dependent kinase were localized to serine residues 490 and 499, and one site of phosphorylation by p34cdc2 was localized to serine 484. In vivo, rap1GAP undergoes phosphorylation at four distinct sites, two of which appear to be identical to the sites phosphorylated by cAMP-dependent kinase in vitro.

Fibrino(geno)lytic Properties of Purified Hementerin, a Metalloproteinase from the Leech Haementeria depressa

1998 ◽  
Vol 80 (07) ◽  
pp. 155-160 ◽  
Author(s):  
Ana Marisa Chudzinski-Tavassi ◽  
Eva Maria Kelen ◽  
Ana Paula de Paula Rosa ◽  
Stephane Loyau ◽  
Claudio Sampaio ◽  
...  
Keyword(s):  
Gel Filtration ◽  
Exchange Chromatography ◽  
Single Chain ◽  
Terminal Sequence ◽  
Calcium Dependent ◽  
Amino Terminal ◽  
Apparent Homogeneity ◽  
Sds Page ◽  
Amino Terminal Sequence

SummaryThe fibrino(geno)lytic protein designated hementerin contained in crude extracts of the salivary complex of Haementeria depressa leeches was purified to apparent homogeneity by gel filtration, ion exchange chromatography and preparative SDS-PAGE. It is a single-chain 80 kDa, PhMeSO2F-resistant, calcium-dependent, metalloproteinase, which specifically degrades fibrin(ogen) through a plasminogen-independent pathway. The amino terminal sequence of 8 residues shows 80% similarity with hementin, another fibrino(geno)lytic protein purified from Haementeria ghilianii leeches. However, their activities differ somewhat in terms of kinetics and with regard to the structure of the fibrin(ogen) fragments they may produce. Cleavage by hementerin of fibrinogen Aα, γ and Bβ chains, in that order, produces 270 kDa to 67 kDa fragments which differ from those produced by plasmin. Hementerin was also able to degrade cross-linked fibrin although at a lower rate as compared to fibrinogen. In conclusion, hementerin is a plasminogen-independent fibrino(geno)lytic metalloproteinase that degrades fibrinogen faster than fibrin, prevents blood coagulation and destroys fibrin clots in vitro.

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