Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracellular alpha-amylase from Lactobacillus fermentum (FERMENTA) was purified by glycogen precipitation and ion exchange chromatography. The purification was approximately 28-fold with a 27% yield. The FERMENTA molecular mass (106,000 Da) is in the same range as the ones determined for L. amylovorus (AMYLOA), L. plantarum (PLANTAA) and L. manihotivorans (MANIHOA) alpha-amylases. The amino acid composition of FERMENTA differs from the other lactobacilli considered here, but however, indicates that the peptidic sequence contains two equal parts: the N-terminal catalytic part; and the C-terminal repeats. The isoelectric point of FERMENTA, PLANTAA, MANIHOA are approximately the same (3.6). The FERMENTA optimum pH (5.0) is slightly more acidic and the optimum temperature is lower (40 degrees C). Raw starch hydrolysis catalyzed by all three amylases liberates maltotriose and maltotretaose. Maltose is also produced by FERMENTA and MANIHOA. Maltohexaose FERMENTA catalyzed hydrolysis produces maltose and maltotriose. Finally, kinetics of FERMENTA, PLANTAA and MANIHOA using amylose as a substrate and acarbose as an inhibitor, were carried out. Statistical analysis of kinetic data, expressed using a general velocity equation and assuming rapid equilibrium, showed that: (1) in the absence of inhibitor k(cat)/Km are, respectively, 1x10(9), 12.6x10(9) and 3.2x10(9) s(-1) M(-1); and (2) the inhibition of FERMENTA is of the mixed non-competitive type (K(1i)=5.27 microM; L(1i)=1.73 microM) while the inhibition of PLANTAA and MANIHOA is of the uncompetitive type (L(1i)=1.93 microM and 1.52 microM, respectively). Whatever the inhibition type, acarbose is a strong inhibitor of these Lactobacillus amylases. These results indicate that, as found in porcine and barley amylases, Lactobacillus amylases contain in addition to the active site, a soluble carbohydrate (substrate or product) binding site.
Comp Biochem Physiol B Biochem Mol Biol 2002 Nov
PMID:Isolation, characterization and inhibition by acarbose of the alpha-amylase from Lactobacillus fermentum: comparison with Lb. manihotivorans and Lb. plantarum amylases. 1243 3

Maltose-binding proteins act as primary receptors in bacterial transport and chemotaxis systems. We report here crystal structures of the thermoacidostable maltose-binding protein from Alicyclobacillus acidocaldarius, and explore its modes of binding to maltose and maltotriose. Further, comparison with the structures of related proteins from Escherichia coli (a mesophile), and two hyperthermophiles (Pyrococcus furiosus and Thermococcus litoralis) allows an investigation of the basis of thermo- and acidostability in this family of proteins.The thermoacidophilic protein has fewer charged residues than the other three structures, which is compensated by an increase in the number of polar residues. Although the content of acidic and basic residues is approximately equal, more basic residues are exposed on its surface whereas most acidic residues are buried in the interior. As a consequence, this protein has a highly positive surface charge. Fewer salt bridges are buried than in the other MBP structures, but the number exposed on its surface does not appear to be unusual. These features appear to be correlated with the acidostability of the A. acidocaldarius protein rather than its thermostability. An analysis of cavities within the proteins shows that the extremophile proteins are more closely packed than the mesophilic one. Proline content is slightly higher in the hyperthermophiles and thermoacidophiles than in mesophiles, and this amino acid is more common at the second position of beta-turns, properties that are also probably related to thermostability. Secondary structural content does not vary greatly in the different structures, and so is not a contributing factor.
J Mol Biol 2004 Jan 02
PMID:X-ray structures of the maltose-maltodextrin-binding protein of the thermoacidophilic bacterium Alicyclobacillus acidocaldarius provide insight into acid stability of proteins. 1465 55

Pyrococcus woesei (DSM 3773) alpha-amylase gene was cloned into pET21d(+) and pYTB2 plasmids, and the pET21d(+)alpha-amyl and pYTB2alpha-amyl vectors obtained were used for expression of thermostable alpha-amylase or fusion of alpha-amylase and intein in Escherichia coli BL21(DE3) or BL21(DE3)pLysS cells, respectively. As compared with other expression systems, the synthesis of alpha-amylase in fusion with intein in E. coli BL21(DE3)pLysS strain led to a lower level of inclusion bodies formation-they exhibit only 35% of total cell activity-and high productivity of the soluble enzyme form (195,000 U/L of the growth medium). The thermostable alpha-amylase can be purified free of most of the bacterial protein and released from fusion with intein by heat treatment at about 75 degrees C in the presence of thiol compounds. The recombinant enzyme has maximal activity at pH 5.6 and 95 degrees C. The half-life of this preparation in 0.05 M acetate buffer (pH 5.6) at 90 degrees C and 110 degrees C was 11 h and 3.5 h, respectively, and retained 24% of residual activity following incubation for 2 h at 120 degrees C. Maltose was the main end product of starch hydrolysis catalyzed by this alpha-amylase. However, small amounts of glucose and some residual unconverted oligosaccharides were also detected. Furthermore, this enzyme shows remarkable activity toward glycogen (49.9% of the value determined for starch hydrolysis) but not toward pullulan.
Mol Biotechnol 2004 Feb
PMID:Cloning of the thermostable alpha-amylase gene from Pyrococcus woesei in Escherichia coli: isolation and some properties of the enzyme. 1476 35

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor, that has been used as a therapeutic agent in facilitating bone marrow and stem cell transplantation and in other clinical cases like neutropenia. Although biologically active recombinant GM-CSF has been successfully produced in Escherichia coli, the reported levels are extremely poor. In this study we looked into the possible reasons for poor expression and found that protein toxicity coupled with protease-based degradation was the principal reason for low productivity. To overcome this problem we attached a signal sequence, as well as an amino-terminal His-tag fusion to the GM-CSF gene. This combination had a dramatic effect on expression levels, which increased from 0.8 microg/mL in the control to 40 microg/mL. When a larger fusion partner, such as the Maltose-binding protein (MBP-tag), was used the expression levels increased further to 69.5 microg/mL, which along with the MBP-tag represented approx 12% of the total cellular protein.
Mol Biotechnol 2005 Jun
PMID:Combined effect of protein fusion and signal sequence greatly enhances the production of recombinant human GM-CSF in Escherichia coli. 1592 Feb 80

Native states of proteins are flexible, populating more than just the unique native conformation. The energetics and dynamics resulting from this conformational ensemble are inherently linked to protein function and regulation. Proteolytic susceptibility is one feature determined by this conformational energy landscape. As an attempt to investigate energetics of proteins on a proteomic scale, we challenged the Escherichia coli proteome with extensive proteolysis and determined which proteins, if any, have optimized their energy landscape for resistance to proteolysis. To our surprise, multiple soluble proteins survived the challenge. Maltose binding protein, a survivor from thermolysin digestion, was characterized by in vitro biophysical studies to identify the physical origin of proteolytic resistance. This experimental characterization shows that kinetic stability is responsible for the unusual resistance in maltose binding protein. The biochemical functions of the identified survivors suggest that many of these proteins may have evolved extreme proteolytic resistance because of their critical roles under stressed conditions. Our results suggest that under functional selection proteins can evolve extreme proteolysis resistance by modulating their conformational energy landscapes without the need to invent new folds, and that proteins can be profiled on a proteomic scale according to their energetic properties by using proteolysis as a structural probe.
J Mol Biol 2007 May 18
PMID:Energetics-based protein profiling on a proteomic scale: identification of proteins resistant to proteolysis. 1740 Feb 45

TrmB is a transcriptional repressor of the hyperthermophilic archaeon Pyrococcus furiosus serving at least two operons. TrmB represses genes encoding an ABC transporter for trehalose and maltose (the TM system) with trehalose and maltose as inducers. TrmB also represses genes encoding another ABC transporter for maltodextrins (the MD system) with maltotriose and sucrose as inducers. Here we report that glucose which was also bound by TrmB acted as a corepressor (causing stronger repression) for both the TM and the MD system. Binding of glucose by TrmB was increased in the presence of TM promoter DNA. Maltose which acted as inducer for the TM system acted as a corepressor for the MD system intensifying repression. We propose that the differential conformational changes of TrmB in response to binding the different sugars governs the ability of TrmB to interact with the promoter region and represents a simple mechanism for selecting the usage of one carbon source over the other, reminiscent of catabolite repression in bacteria.
Mol Microbiol 2007 Jun
PMID:Differential signal transduction via TrmB, a sugar sensing transcriptional repressor of Pyrococcus furiosus. 1750 72

Maltose-binding protein (MBP) is a carrier protein for high level recombinant protein and peptide production from either the cytoplasm or periplasm of Escherichia coli. The affinity matrix for purifying MBP-passenger proteins utilizes amylose covalently attached to magnetic beads, agarose, or a chemically inert fast protein liquid chromatography (FPLC) matrix--exploiting the natural affinity of MBP for alpha-(1-->4)-maltodextrins in the stationary phase. A fundamental problem is the expression and purification failure of as much as 30% of all constructs, which is limiting for one of the best solubilizing carrier proteins available for recombinant expression. In this chapter, we have discussed aspects of MBP biology that can impact upon binding to the amylose affinity matrix including cloning considerations, structural complications, hydrophobic buffer additives and the presence of cellular biomolecules that bind or modify the matrix during purification. Chromatography conditions are presented for purification at very small scales of less than 0.5 mL using amylose magnetic beads, a batch and semi-batch method for small to moderate scale purifications up to approximately 35 mg and larger scale FPLC methods. A novel matrix-assisted dialysis refolding method is also described whereby MBP-passenger proteins can be refolded in the presence of amylose matrix in instances where native purification methods fail to bind the amylose matrix.
Methods Mol Biol 2008
PMID:Amylose affinity chromatography of maltose-binding protein: purification by both native and novel matrix-assisted dialysis refolding methods. 1882 55

In most plants, a large fraction of photo-assimilated carbon is stored in the chloroplasts during the day as starch and remobilized during the subsequent night to support metabolism. Mutations blocking either starch synthesis or starch breakdown in Arabidopsis thaliana reduce plant growth. Maltose is the major product of starch breakdown exported from the chloroplast at night. The maltose excess 1 mutant (mex1), which lacks the chloroplast envelope maltose transporter, accumulates high levels of maltose and starch in chloroplasts and develops a distinctive but previously unexplained chlorotic phenotype as leaves mature. The introduction of additional mutations that prevent starch synthesis, or that block maltose production from starch, also prevent chlorosis of mex1. In contrast, introduction of mutations in disproportionating enzyme (DPE1) results in the accumulation of maltotriose in addition to maltose, and greatly increases chlorosis. These data suggest a link between maltose accumulation and chloroplast homeostasis. Microscopic analyses show that the mesophyll cells in chlorotic mex1 leaves have fewer than half the number of chloroplasts than wild-type cells. Transmission electron microscopy reveals autophagy-like chloroplast degradation in both mex1 and the dpe1/mex1 double mutant. Microarray analyses reveal substantial reprogramming of metabolic and cellular processes, suggesting that organellar protein turnover is increased in mex1, though leaf senescence and senescence-related chlorophyll catabolism are not induced. We propose that the accumulation of maltose and malto-oligosaccharides causes chloroplast dysfunction, which may by signaled via a form of retrograde signaling and trigger chloroplast degradation.
Mol Plant 2009 Nov
PMID:Blocking the metabolism of starch breakdown products in Arabidopsis leaves triggers chloroplast degradation. 1994 17

Maltose-binding protein (MBP) is one of the most popular fusion partners being used for producing recombinant proteins in bacterial cells. MBP allows one to use a simple capture affinity step on amylose-agarose columns, resulting in a protein that is often 70-90% pure. In addition to protein-isolation applications, MBP provides a high degree of translation and facilitates the proper folding and solubility of the target protein. This chapter describes efficient procedures for isolating highly purified MBP-target proteins. Special attention is given to considerations for downstream applications such as structural determination studies, protein activity assays, and assessing the chemical characteristics of the target protein.
Methods Mol Biol 2011
PMID:Purification of proteins fused to maltose-binding protein. 2097 71

At present the protein expression systems used commonly by researchers incorporate an affinity tail fused to the protein of interest. These affinity tails provide a convenient and efficient method for the purification of the expressed fusion protein using affinity chromatography. Many different affinity tails have been developed and a few of the commonly used fusion protein expression systems are listed in Table 1. The plasmid expression vectors for the production of fusion proteins in various hosts are available commercially and with the advent of the polymerase chain reaction (PCR) any gene of known sequence can be cloned into any expression vector. Most affinity tails are linked to the N-terminus of the protein of interest, but some affinity tails are able to be linked to either the N- or C-terminus of the protein of interest. The choice of affinity tail to use for the expression of any particular protein is empirical since the factors leading to the high expression of recombinant proteins in foreign hosts have yet to be elucidated. Table 1 Systems Commonly Used for the Expression of Recombinant Fusion Proteins in E. coli ( a ) Affinity tail Elution ligand Supplier References Glutathione S-transferase Glutathione Pharmacra (5) Transitional metals Transrtional metals Qiagen, Inc (6,7) Bmdmg polypepttdes e.g,Zn(2+),Cu(2+),N(1) (2+) Maltose bmdmg protein Maltose New England (8) Biolabs Staphylococcus aureus IgG Pharmacia (9) protein A Biotmylated pepttdes Streptavidin or Promega Promega avidin ( a )Transrtronal metal brndlng polypepttdes can be fused to either the N or C terminus of proteins.
Methods Mol Med 1998
PMID:The use of recombinant fusion proteases in the affinity purification of recombinant proteins. 2139 Aug 52


<< Previous 1 2 3 Next >>