scholarly journals Allosteric serine hydroxymethyltransferase from monkey liver: Temperature induced conformational transitions

1981 ◽  
Vol 3 (2) ◽  
pp. 179-190 ◽  
Author(s):  
Kashi S. Ramesh ◽  
V. S. Ananthanarayanan ◽  
N. Appaji Rao
Keyword(s):  
Conformational Transitions ◽  
Serine Hydroxymethyltransferase ◽  
Monkey Liver

scholarly journals Regulation of monkey liver serine hydroxymethyltransferase by nicotinamide nucleotide

1978 ◽  
Vol 174 (3) ◽  
pp. 1055-1058 ◽  
Author(s):  
K S Ramesh ◽  
N A Rao
Keyword(s):  
Serine Hydroxymethyltransferase ◽  
Monkey Liver ◽  
First Time ◽  
Metabolic Interconversion ◽  
Time Lead

The positive homotropic binding of tetrahydrofolate to monkey liver serine hydroxymethyltransferase was abolished on preincubating the enzyme with NADH and NADPH. NAD+ was a negative heterotropic effector, whereas NADP+ was without effect. The allosteric effects of nicotinamide nucleotides on the serine hydroxymethyltransferase, reported for the first time, lead to a better understanding of the regulation of the metabolic interconversion of folate coenzymes.

scholarly journals Inhibition of monkey liver serine hydroxymethyltransferase by Cibacron Blue 3G-A

1980 ◽  
Vol 187 (1) ◽  
pp. 249-252 ◽  
Author(s):  
K S Ramesh ◽  
N Appaji Rao
Keyword(s):  
Absorption Spectrum ◽  
Binding Domain ◽  
Serine Hydroxymethyltransferase ◽  
Free Enzyme ◽  
Cibacron Blue ◽  
Monkey Liver ◽  
Dye Absorption ◽  
Blue Sepharose

Cibacron Blue 3G-A inhibited monkey liver serine hydroxymethyltransferase competitively with respect to tetrahydrofolate and non-competitively with respect to L-serine. NADH, a positive heterotropic effector, failed to protect the enzymes against inhibition by the dye and was unable to desorb the enzyme from Blue Sepharose CL-6B gel matrix. The binding of the dye to the free enzyme was confirmed by changes in the dye absorption spectrum. The results indicate that the dye probably binds at the tetrahydrofolate-binding domain of the enzyme, rather than at the ‘dinucleotide fold’.

Conformational transitions driven by pyridoxal-5′-phosphate uptake in the psychrophilic serine hydroxymethyltransferase from P sychromonas ingrahamii

2014 ◽  
Vol 82 (10) ◽  
pp. 2831-2841 ◽  
Author(s):  
Sebastiana Angelaccio ◽  
Florian Dworkowski ◽  
Angela Di Bello ◽  
Teresa Milano ◽  
Guido Capitani ◽  
...  
Keyword(s):  
Phosphate Uptake ◽  
Conformational Transitions ◽  
Serine Hydroxymethyltransferase

scholarly journals Purification and physicochemical, kinetic and immunological properties of allosteric serine hydroxymethyltransferase from monkey liver

1980 ◽  
Vol 187 (3) ◽  
pp. 623-636 ◽  
Author(s):  
K S Ramesh ◽  
N Appaji Rao
Keyword(s):  
Liver Enzyme ◽  
Thermal Inactivation ◽  
Heat Stability ◽  
Serine Hydroxymethyltransferase ◽  
Heat Denaturation ◽  
Monkey Liver ◽  
Catalytically Active ◽  
Antibody Complex ◽  
Bacterial Sources ◽  
Blue Sepharose

The homogeneous serine hydroxymethyltransferase purified from monkey liver, by the use of Blue Sepharose affinity chromatography, exhibited positive homotropic co-operative interactions (h = 2.5) with tetrahydrofolate and heterotropic interactions with L-serine and nicotinamide nucleotides. The enzyme had an unusually high temperature optimum of 60 degrees C and was protected against thermal inactivation by L-serine. The allosteric effects were abolished when the monkey liver enzyme was purified by using a heat-denaturation step in the presence of L-serine, a procedure adopted by earlier workers for the purification of this enzyme from mammalian and bacterial sources. The enzyme activity was inhibited completely by N5-methyltetrahydrofolate, N5-formyltetrahydrofolate, dichloromethotrexate, aminopterin and D-cycloserine, whereas methotrexate and dihydrofolate were partial inhibitors. The insoluble monkey liver enzyme-antibody complex was catalytically active and failed to show positive homotropic co-operative interactions with tetrahydrofolate (h = 1) and heterotropic interactions with NAD+. The enzyme showed a higher heat-stability in a complex with its antibody than as the free enzyme. These results highlight the pitfalls in using a heat-denaturation step in the purification of allosteric enzymes.

Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM

1988 ◽  
Vol 46 ◽  
pp. 176-177
Author(s):  
J.S. Wall ◽  
V. Maridiyan ◽  
S. Tumminia ◽  
J. Hairifeld ◽  
M. Boublik
Keyword(s):  
Ionic Strength ◽  
Three Dimensional ◽  
Conformational Transitions ◽  
Dark Field ◽  
Dimensional Structure ◽  
Ribosomal Rnas ◽  
Field Mode ◽  
Freeze Dried ◽  
High Resolution Images ◽  
Low Ionic Strength

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).

Conformational transitions and dynamics of thermal responsive poly(N-isopropylacrylamide) polymers as revealed by molecular simulation

2014 ◽  
Vol 55 ◽  
pp. 153-159 ◽  
Author(s):  
Ming S. Liu ◽  
Cheryl Taylor ◽  
Bill Chong ◽  
Lihui Liu ◽  
Ante Bilic ◽  
...  
Keyword(s):  
Molecular Simulation ◽  
Conformational Transitions
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