Properties of Inosinic Acid Dehydrogenase from Bacillus subtilis. II. Kinetic Properties

1973 ◽  
Vol 51 (10) ◽  
pp. 1391-1398 ◽  
Author(s):  
Tai-Wing Wu ◽  
K. G. Scrimgeour
Keyword(s):  
Bacillus Subtilis ◽  
Kinetic Properties ◽  
Ph Optimum ◽  
Ionic Radii ◽  
Imp Dehydrogenase ◽  
Inosinic Acid ◽  
Feedback Inhibitor ◽  
Enzyme Change ◽  
A Site ◽  
Complex Manner

Some of the kinetic properties of inosine 5′-phosphate (IMP) dehydrogenase purified from Bacillus subtilis have been described. K+ can be replaced as an activator by other monovalent cations, whose activities are related to their ionic radii. IMP dehydrogenase is stimulated by appropriate concentrations of adenosine 5′-phosphate, and is strongly inhibited by the antibiotic mycophenolic acid. The enzyme is inhibited by guanosine 5′-phosphate (GMP), a suspected negative feedback inhibitor, in a complex manner. Desensitization of this inhibition suggests that GMP binds at a site distinct from the catalytic site. Several properties of the enzyme change after desensitization. For example, the pH optimum shifts from pH 7.55 to pH 8.4, and whereas the inhibition by GMP is greatly reduced there is an increase in catalytic activity. These studies and the oligomeric structure of IMP dehydrogenase strongly indicate a regulatory role for the enzyme in B. subtilis.

Properties of Inosinic Acid Dehydrogenase from Bacillus subtilis. I. Purification and Physical Properties

1973 ◽  
Vol 51 (10) ◽  
pp. 1380-1390 ◽  
Author(s):  
Tai-Wing Wu ◽  
K. G. Scrimgeour
Keyword(s):  
Bacillus Subtilis ◽  
Quaternary Structure ◽  
Active Form ◽  
Kinetic Properties ◽  
Purification Method ◽  
Molecular Weights ◽  
Inosinic Acid ◽  
Apparent Homogeneity ◽  
Catalytically Active ◽  
Membrane Bound

IMP (inosinic acid or inosine-5′-phosphate) dehydrogenase has been purified to apparent homogeneity from Bacillus subtilis. The purification method yields an enzyme preparation that retains a constant level of inhibition by guanosine 5′-phosphate. The enzyme is membrane bound, and can be removed from membrane material after treatment either with detergents or with phospholipase A. Both the membrane-bound and solubilized forms of IMP dehydrogenase have similar kinetic properties. The soluble enzyme can occur in a number of oligomeric forms, with molecular weights that are multiples of 100 000 daltons. Although both the tetramer and the dimer appear to be catalytically active, no conclusions can yet be drawn about the quaternary structure of the enzymically active form(s).

Properties of Inosine-5′-phosphate Dehydrogenase from Bacillus subtilis

1971 ◽  
Vol 49 (4) ◽  
pp. 473-475 ◽  
Author(s):  
Tai-Wing Wu ◽  
K. G. Scrimgeour
Keyword(s):  
Molecular Weight ◽  
Bacillus Subtilis ◽  
High Molecular Weight ◽  
Cooperative Interaction ◽  
Imp Dehydrogenase ◽  
Protein Subunits ◽  
Apparent Homogeneity ◽  
Complex Manner

Inosine-5′-phosphate (IMP) dehydrogenase has been purified to apparent homogeneity from extracts of Bacillus subtilis. The enzyme is inhibited by GMP in a complex manner which suggests cooperative interaction between protein subunits of IMP dehydrogenase. Several techniques have been used to desensitize the enzyme to inhibition by GMP. IMP dehydrogenase has a high molecular weight, and is composed of subunits each with a molecular weight of approximately 100 000. The properties of IMP dehydrogenase from B. subtilis are compatible with its being a regulatory enzyme in the biosynthesis of GMP from IMP.

scholarly journals Purification and some kinetic properties of rat liver glucosamine synthetase

1971 ◽  
Vol 121 (4) ◽  
pp. 701-709 ◽  
Author(s):  
P. J. Winterburn ◽  
C. F. Phelps
Keyword(s):  
Rat Liver ◽  
Rate Equation ◽  
Protective Action ◽  
The Other ◽  
Kinetic Properties ◽  
Ph Optimum ◽  
Ph Values ◽  
Catalysed Reaction ◽  
Ping Pong ◽  
Feedback Inhibitor

1. Glucosamine synthetase (l-glutamine–d-fructose 6-phosphate aminotransferase, EC 2.6.1.16) was purified about 300-fold from rat liver by two techniques. One procedure utilized the protective action of fructose 6-phosphate and gave a relatively stable preparation, the other yielded an unstable enzyme (half-life of about 20h), free of contaminant activities, on which kinetic experiments were performed. Although the properties of the two preparations showed slight differences, the unstabilized form could be converted into the stabilized form. 2. During preparation the enzyme retained its sensitivity to the feedback inhibitor, UDP-N-acetylglucosamine. 3. The reversibility of the enzyme-catalysed reaction could not be demonstrated. There was no apparent requirement for a cofactor. 4. The pH optimum was at 7.5, at which pH the reaction obeyed a Ping Pong Bi Bi rate equation. At pH values outside the range 6.9–7.6 and at temperatures below 29°C the velocity was described by an ordered Bi Bi rate equation. 5. The molecular weight of the enzyme, determined by two procedures, was 360000–400000. 6. The aminotransferase was unable to utilize ammonia as a substrate.

scholarly journals Role of SpoVA Proteins in Release of Dipicolinic Acid during Germination of Bacillus subtilis Spores Triggered by Dodecylamine or Lysozyme

2006 ◽  
Vol 189 (5) ◽  
pp. 1565-1572 ◽  
Author(s):  
Venkata Ramana Vepachedu ◽  
Peter Setlow
Keyword(s):  
Bacillus Subtilis ◽  
Small Molecules ◽  
Spore Germination ◽  
Dipicolinic Acid ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Ph Optimum ◽  
Inner Membrane ◽  
Temperature Sensitive Mutants

ABSTRACT The release of dipicolinic acid (DPA) during the germination of Bacillus subtilis spores by the cationic surfactant dodecylamine exhibited a pH optimum of ∼9 and a temperature optimum of 60°C. DPA release during dodecylamine germination of B. subtilis spores with fourfold-elevated levels of the SpoVA proteins that have been suggested to be involved in the release of DPA during nutrient germination was about fourfold faster than DPA release during dodecylamine germination of wild-type spores and was inhibited by HgCl2. Spores carrying temperature-sensitive mutants in the spoVA operon were also temperature sensitive in DPA release during dodecylamine germination as well as in lysozyme germination of decoated spores. In addition to DPA, dodecylamine triggered the release of amounts of Ca2+ almost equivalent to those of DPA, and at least one other abundant spore small molecule, glutamic acid, was released in parallel with Ca2+ and DPA. These data indicate that (i) dodecylamine triggers spore germination by opening a channel in the inner membrane for Ca2+-DPA and other small molecules, (ii) this channel is composed at least in part of proteins, and (iii) SpoVA proteins are involved in the release of Ca2+-DPA and other small molecules during spore germination, perhaps by being a part of a channel in the spore's inner membrane.

Hydrothermal synthesis of ABi2Ta2O9Aurivillius phase: A comparative study of A-site cation size on structure, dielectric, optical properties

2021 ◽  
Author(s):  
Ilona Bella ◽  
Tio Putra Wendari ◽  
Novesar Jamarun ◽  
Nandang Mufti ◽  
Zulhadjri
Keyword(s):  
Xrd Analysis ◽  
Aurivillius Phase ◽  
Hydrothermal Route ◽  
Orthorhombic Crystal ◽  
Ionic Radii ◽  
Aurivillius Phases ◽  
Orthorhombic Crystal Structure ◽  
A Site ◽  
Cation Size ◽  
Ferroelectric Transition Temperature

In this study, the double-layered Aurivillius phases CaBi2Ta2O9 (CBT) and PbBi2Ta2O9 (PBT) were prepared through a hydrothermal route with NaOH as a mineralizer. XRD analysis confirmed that the CBT and PBT compounds were successfully formed and adopted an orthorhombic crystal structure with an [Formula: see text]21am symmetry. Le Bail refinements of XRD data indicated that the unit cell volume of CBT was smaller than PBT and is associated with the smaller ionic radius of Ca[Formula: see text] compared to Pb[Formula: see text]. The surface morphology of both samples, as determined using SEM, demonstrated plate-like grains with anisotropic grain growth. It was found that the different ionic radii of [Formula: see text]-site cations (Ca[Formula: see text] and Pb[Formula: see text] strongly affected the structural, optical and electrical properties of the Aurivillius phase. The occupation of smaller Ca[Formula: see text] cations induced a higher structural distortion, which resulted in higher bandgap ([Formula: see text] energy and ferroelectric transition temperature ([Formula: see text] of CBT, compared to those of PBT.

scholarly journals DIRECTED EVOLUTION OF METABOLIC PATHWAYS IN MICROBIAL POPULATIONS. I. MODIFICATION OF THE ACID PHOSPHATASE pH OPTIMUM IN S. CEREVISIAE

Genetics ◽  
1972 ◽  
Vol 70 (1) ◽  
pp. 59-73 ◽  
Author(s):  
J C Francis ◽  
P E Hansche
Keyword(s):  
Acid Phosphatase ◽  
Metabolic Pathways ◽  
Experimental System ◽  
Microbial Populations ◽  
Kinetic Properties ◽  
Mutational Event ◽  
Ph Optimum ◽  
Functional Changes ◽  
Evolution Of Metabolic Pathways ◽  
Wide Range

ABSTRACT An experimental system for directing the evolution of enzymes and metabolic pathways in microbial populations is proposed and an initial test of its power is provided.—The test involved an attempt to genetically enhance certain functional properties of the enzyme acid phosphatase in S. cerevisiae by constructing an environment in which the functional changes desired would be "adaptive". Naturally occurring mutations in a population of 109 cells were automatically and continuously screened, over 1,000 generations, for their effect on the efficiency (Km) and activity of acid phosphatase at pH 6, and for their effect on the efficiency of orthophosphate metabolism.—The first adaptation observed, M1, was due to a single mutational event that effected a 30% increase in the efficiency of orthophosphate metabolism. The second, M2, effected an adaptive shift in the pH optimum of acid phosphatase and an increase in its activity over a wide range of pH values (an increment of 60% at pH 6). M2 was shown to result from a single mutational event in the region of the acid phosphatase structural gene. The third, M3, effected cell clumping, an adaptation to the culture apparatus that had no effect on phosphate metabolism.—The power of this system for directing the evolution of enzymes and of metabolic pathways is discussed in terms of the kinetic properties of the experimental system and in terms of the results obtained.

Structural and kinetic properties of Bacillus subtilis S-adenosylmethionine synthetase expressed in Escherichia coli

2008 ◽  
Vol 1784 (12) ◽  
pp. 1949-1958 ◽  
Author(s):  
Venu Kamarthapu ◽  
Khareedu Venkateswara Rao ◽  
P.N.B.S. Srinivas ◽  
G. Bhanuprakash Reddy ◽  
Vudem Dashavantha Reddy
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Kinetic Properties ◽  
Adenosylmethionine Synthetase

scholarly journals Evaluation of the Kinetic Properties of the Sporulation Protein SpoIIE of Bacillus subtilis by Inclusion in a Model Membrane

2004 ◽  
Vol 186 (10) ◽  
pp. 3195-3201 ◽  
Author(s):  
Tim Searls ◽  
Xingyong Chen ◽  
Stephanie Allen ◽  
Michael D. Yudkin
Keyword(s):  
Bacillus Subtilis ◽  
Conformational Changes ◽  
Asymmetric Cell Division ◽  
Developmental Process ◽  
Model Membrane ◽  
In Vitro Assays ◽  
Kinetic Properties ◽  
Local Concentration ◽  
Phosphatase Domain

ABSTRACT Starvation induces Bacillus subtilis to initiate a developmental process (sporulation) that includes asymmetric cell division to form the prespore and the mother cell. The integral membrane protein SpoIIE is essential for the prespore-specific activation of the transcription factor σF, and it also has a morphogenic activity required for asymmetric division. An increase in the local concentration of SpoIIE at the polar septum of B. subtilis precedes dephosphorylation of the anti-anti-sigma factor SpoIIAA in the prespore. After closure and invagination of the asymmetric septum, phosphatase activity of SpoIIE increases severalfold, but the reason for this dramatic change in activity has not been determined. The central domain of SpoIIE has been seen to self-associate (I. Lucet et al., EMBO J. 19:1467-1475, 2000), suggesting that activation of the C-terminal PP2C-like phosphatase domain might be due to conformational changes brought about by the increased local concentration of SpoIIE in the sporulating septum. Here we report the inclusion of purified SpoIIE protein into a model membrane as a method for studying the effect of local concentration in a lipid bilayer on activity. In vitro assays indicate that the membrane-bound enzyme maintains dephosphorylation rates similar to the highly active micellar state at all molar ratios of protein to lipid. Atomic force microscopy images indicate that increased local concentration does not lead to self-association.

GERMINATION OF BACTERIAL ENDOSPORES WITH SUBTILOPEPTIDASES

1967 ◽  
Vol 13 (5) ◽  
pp. 489-501 ◽  
Author(s):  
Gonzalo Sierra
Keyword(s):  
Bacillus Subtilis ◽  
Proteolytic Enzyme ◽  
Prolonged Exposure ◽  
Enzymatic Reaction ◽  
Significant Loss ◽  
Anaerobic Conditions ◽  
Genus Bacillus ◽  
Ph Optimum ◽  
Diisopropyl Fluorophosphate ◽  
Bacterial Endospores

Intact spores of Bacillus subtilis are susceptible to subtilopeptidase attack and this enzymatic reaction induces changes in the spore similar to those that take place during "physiological" germination. Germination occurred between pH 5.5 and 10.0 showing a pH optimum of 9.0 and between 25 °C and 45 °C with an optimum of 37–40°. Subtilopeptidase-induced germination took place in completely anaerobic conditions. Sublethal heating of spore suspensions increased the rate of subtilopeptidase-induced germination. Germination with subtilopeptidase was almost completely inhibited by an excess of diisopropyl fluorophosphate. L-Alanine-induced germination was not affected by diisopropyl fluorophosphate. Participation of the spore metabolism in subtilopeptidase-induced germination seemed likely. These results suggest that subtilopeptidases initiate spore germination by releasing germination agents from the spore.No significant loss of viability was noted until after exposure to the proteolytic enzyme for at least 60 minutes. Prolonged exposure of B. subtilis spores to subtilopeptidase results in death of the exposed spores.Subtilopeptidase-induced germination was also observed in several spores of other members of the genus Bacillus.

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