The High-Km Cyclic AMP Phosphodiesterase of Baker's Yeast is a Zinc Metalloenzyme

1978 ◽  
Vol 6 (6) ◽  
pp. 1218-1220 ◽  
Author(s):  
JOHN LONDESBOROUGH
Keyword(s):  
Cyclic Amp ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Cyclic Amp Phosphodiesterase

scholarly journals A stereochemical investigation of the hydrolysis of cyclic AMP and the (Sp)-and (Rp)-diastereoisomers of adenosine cyclic 3′:5′-phosphorothioate by bovine heart and baker's-yeast cyclic AMP phosphodiesterases

1982 ◽  
Vol 203 (2) ◽  
pp. 461-470 ◽  
Author(s):  
R L Jarvest ◽  
G Lowe ◽  
J Baraniak ◽  
W J Stec
Keyword(s):  
Cyclic Amp ◽  
Phosphorus Atom ◽  
Metal Ion ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Bivalent Metal ◽  
Cyclic Amp Phosphodiesterase ◽  
Bovine Heart ◽  
Hydrolysis Of

Bovine heart cyclic AMP phosphodiesterase, which has a requirement for Mg2+, hydrolyses cyclic AMP with inversion of configuration at the phosphorus atom, but only the (Sp)-diastereoisomer of adenosine cyclic 3′:5′-phosphorothioate is hydrolysed by this enzyme. By contrast, the low-affinity yeast cyclic AMP phosphodiesterase, which contains tightly bound Zn2+, hydrolyses both the (Sp)- and the (Rp)-diastereoisomers of adenosine cyclic 3′:5′-phosphorothioate, the (Rp)-diastereoisomer being the preferred substrate under V max. conditions. Both of the diastereoisomers of adenosine cyclic 3′:5′-phosphorothioate, as well as cyclic AMP, are hydrolysed with inversion of configuration at the phosphorus atom by the yeast enzyme. It is proposed that, with both enzymes, the bivalent metal ion co-ordinates with the phosphate residue of the substrate, and that hydrolysis is catalysed by a direct ‘in-line’ mechanism.

scholarly journals Solubilization and other studies on adenylate cyclase of baker's yeast

1976 ◽  
Vol 159 (2) ◽  
pp. 363-370 ◽  
Author(s):  
K Varimo ◽  
J Londesborough
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Gel Filtration ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Centrifugal Forces ◽  
Wide Range ◽  
Solubilized Enzyme ◽  
Fold Activation

1. Adenylate cyclase of Saccharomyces cerevisiae was sedimented from mechanically disintegrated preparations of yeast over an unusually wide range of centrifugal forces. 2. The enzyme was readily solubilized by Ficoll and by Lubrol PX. Lubrol caused a 2-fold activation. 3. Both particle-bound and Lubrol-solubilized enzyme had an apparent Km for ATP of 1.6 mM in the presence of 0.4 mM-cyclic AMP and 5 mM-MnCl2 at pH 6.2 and 30°C. 4. The Lubrol-solubilized enzyme behaved on gel filtration as a monodisperse protein with an apparent mol.wt. of about 450000.

scholarly journals Characterization of two trehalases in baker's yeast

1984 ◽  
Vol 219 (2) ◽  
pp. 511-518 ◽  
Author(s):  
J Londesborough ◽  
K Varimo
Keyword(s):  
Acetic Acid ◽  
Cyclic Amp ◽  
Concanavalin A ◽  
Soluble Fraction ◽  
Gel Filtration ◽  
Baker’S Yeast ◽  
Acidic Protein ◽  
Baker's Yeast ◽  
Ph Optimum

Trehalase activities at pH 5 (not inhibited by EDTA) and pH 7 (inhibited by EDTA) were present in the soluble fraction of disintegrated commercial baker's yeast. The pH 5 activity binds strongly to concanavalin A, is only partially salted out by saturated (NH4)2SO4, has an apparent Mr of 215000 (by gel filtration) and is an acidic protein. It has a Km of 1.4 mM, a broad pH optimum (at 40 mM-trehalose) between pH 4 and 5, and is activated by about 30% by 20-300 mM neutral salts such as KCl, NaNO3 and MnCl2. The enzyme is strongly inhibited by acetic acid/acetate buffers, with a Ki of about 15 mM-acetic acid. The pH 7 activity does not bind to concanavalin A, is salted out at 20-32% (w/v) (NH4)2SO4 and has an Mr of 170000 (by gel filtration). It is absolutely dependent on Ca2+ or Mn2+ ions (Mg2+ is ineffective) and strongly inhibited by neutral salts in the 20-100 mM range. It can be activated by treatment with MgATP in the presence of cyclic AMP. Activation decreases, but does not abolish, the Ca2+ requirement, and does not change the Km for trehalose (5.7 mM) or shift the sharp pH optimum at pH 6.7 (at 40 mM-trehalose).

scholarly journals Characterization of an adenosine 3′:5′-cyclic monophosphate phosphodiesterase from baker's yeast. Its binding to subcellular particles, catalytic properties and gel-filtration behaviour

1977 ◽  
Vol 163 (3) ◽  
pp. 467-476 ◽  
Author(s):  
J Londesborough
Keyword(s):  
Ionic Strength ◽  
Cyclic Amp ◽  
Microsomal Fraction ◽  
Gel Filtration ◽  
Potassium Phosphate ◽  
Apparent Molecular Weight ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Ph Optimum

1. The 3′:5′-cyclic AMP phosphodiesterase in the microsomal fraction of baker's yeast is highly specific for cyclic AMP, and not inhibited by cyclic GMP, cyclic IMP or cyclic UMP. Catalytic activity is abolished by 30 micrometer-EDTA. At 30 degrees C and pH8.1, the Km is 0.17 micrometer, and theophylline is a simple competitive inhibitor with Ki 0.7 micrometer. The pH optimum is about 7.8 at 0.25 micrometer-cyclic AMP, so that over the physiological range of pH in yeast the activity changes in the opposite direction to that of adenylate cyclase [PH optimum about 6.2; Londesborough & Nurminen (1972) Acta Chem. Scand. 26, 3396-3398].2. At pH 7.2, dissociation of the enzyme from dilute microsomal suspensions increased with ionic strength and was almost complete at 0.3 M-KCl. MgCl2 caused more dissociation than did KCl or NaCl at the same ionic strength, but at low KCl concentrations binding required small amounts of free bivalent metal ions. In 0.1 M-KCl the binding decreased between pH 4.7 and 9.3. At pH 7.2 the binding was independent of temperature between 5 and 20 degrees C. These observations suggest that the binding is electrostatic rather than hydrophobic. 3. The proportion of bound activity increased with the concentration of the microsomal fraction, and at 22 mg of protein/ml and pH 7.2 was 70% at I0.18, and 35% at I0.26. Presumably a substantial amount of the enzyme is particle-bound in vivo. 4. At 5 degrees C in 10 mM-potassium phosphate, pH 7.2, the apparent molecular weight of KCl-solubilized enzyme decreased with enzyme concentration from about 200 000 to 40 000. In the presence of 0.5M-KCl, a constant mol.wt. of about 55 000 was observed over a 20-fold range of enzyme concentrations.

The Effect of Mitomycin C on Platelet Aggregation and Adenosine 3′, 5′-Monophosphate Metabolism

1978 ◽  
Vol 39 (01) ◽  
pp. 177-185 ◽  
Author(s):  
Shuichi Hashimoto ◽  
Sachiko Shibata ◽  
Bonro Kobayashi
Keyword(s):  
Platelet Aggregation ◽  
Cyclic Amp ◽  
Mitomycin C ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Cellular Membrane ◽  
Adenyl Cyclase ◽  
Cyclic Amp Phosphodiesterase ◽  
Membrane Structure And Function ◽  
And Function

SummaryThe effect of Mitomycin C on aggregation, adenosine 3′, 5′-monophosphate (cyclic AMP) metabolism and reactions induced by thrombin was studied in rabbit platelets. Mitomycin C inhibited the platelet aggregation induced by adenosine diphosphate or thrombin. The level of radioactive cyclic AMP derived from 8-14C adenine or 8-14C adenosine increased after incubating intact platelets with Mitomycin G. Formation of radioactive adenosine triphosphate also increased though mitochondrial oxidation was not stimulated. Similar effect was observed also in rabbit liver. Mitomycin C failed to stimulate platelet adenyl cyclase but inhibited cyclic AMP phosphodiesterase in the absence of theophylline. In the platelets preincubated with Mitomycin C, thrombin-induced inhibition of adenyl cyclase, stimulation of membrane-bound cyclic AMP phosphodiesterase, and release of 250,000 dalton protein from platelet membranes were prevented. These results suggest that Mitomycin C will affect cellular membrane structure and function, and this extranuclear effect of Mitomycin C will lead to inhibition of aggregation in blood platelets.

Cyclic AMP phosphodiesterase in diabetes. Effect of glyburide

Diabetes ◽  
1986 ◽  
Vol 35 (11) ◽  
pp. 1233-1236 ◽  
Author(s):  
S. S. Solomon ◽  
J. Deaton ◽  
T. P. Shankar ◽  
M. Palazzolo
Keyword(s):  
Cyclic Amp ◽  
Cyclic Amp Phosphodiesterase
Sign in / Sign up

Export Citation Format

Share Document