THE EFFECT OF PRESSURE ON THE SPONTANEOUS HYDROLYSIS OF ACETYL PHOSPHATE MONO-ANION AND DI-ANION AND OF ACETYL PHENYL PHOSPHATE MONO-ANION

1962 ◽  
Vol 40 (6) ◽  
pp. 1220-1224 ◽  
Author(s):  
G. Di Sabato ◽  
W. P. Jencks ◽  
E. Whalley
Keyword(s):  
Acetyl Phosphate ◽  
Effect Of Pressure ◽  
Phenyl Phosphate ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of

not available

Reactions of acyl phosphates. Base hydrolysis of [Co(NH3)5OPO3COCH3]+ and the metal hydroxide promoted hydrolysis of acetyl phenyl phosphate

1981 ◽  
Vol 34 (8) ◽  
pp. 1769 ◽  
Author(s):  
DA Buckingham ◽  
CR Clark
Keyword(s):  
Hydroxo Complex ◽  
Metal Hydroxide ◽  
Base Hydrolysis ◽  
Acetyl Phosphate ◽  
Carbonyl Carbon ◽  
Phenyl Phosphate ◽  
Hydrolysis Of ◽  
Oxygen Bond

Tracer 18O studies have established that base hydrolysis of coordinated acetyl phosphate in [(NH3)5Co-OPO3COCH3]+ (kOH 0.53 mol-1 dm3 s-1, 25°C, I 1.0 NaClO4) proceeds with exclusive carbon-oxygen bond fission. The hydrolysis of acetyl phenyl phosphate monoanion is significantly catalysed by the exchange-inert hydroxo complex [(NH3)5Co-OH]2+ (kMOH 2.9 × 10-2 mol-1 dm3 s-1, 25°) which operates through a nucleophilic pathway involving attack at carbonyl carbon.

Effect of pressure on the α-amylase catalyzed hydrolysis of starch

1964 ◽  
Vol 6 (4) ◽  
pp. 469-471 ◽  
Author(s):  
Richard G. Griskey ◽  
Thomas Richter
Keyword(s):  
Effect Of Pressure ◽  
Hydrolysis Of

Effect of Pressure on the Hydrolysis of the Ethyleneiminium Ion

1965 ◽  
Vol 69 (5) ◽  
pp. 1751-1753 ◽  
Author(s):  
B. T. Baliga ◽  
A. K. Rantamaa ◽  
E. Whalley
Keyword(s):  
Effect Of Pressure ◽  
Hydrolysis Of

THE ACETYLATION OF THROMBIN

1959 ◽  
Vol 37 (1) ◽  
pp. 1361-1366 ◽  
Author(s):  
Ricardo H. Landaburu ◽  
Walter H. Seegers
Keyword(s):  
Methyl Ester ◽  
Proteolytic Activity ◽  
Basic Structure ◽  
Amino Groups ◽  
Spontaneous Hydrolysis ◽  
Optimum Ph ◽  
Hydrolysis Of

Purified thrombin-C loses its clotting power upon acetylation. The thrombin-E which is produced during the acetylation has approximately twice the proteolytic activity as the original thrombin-C. Evidently amino groups are not necessary to have thrombin-E activity, but if o-acyl groups are also produced the enzyme does not hydrolyze p-toluenesulphonylarginine methyl ester (TAMe). The activity can be recovered by spontaneous hydrolysis of the o-acyl groups at pH 8.5. Thrombin-E does not activate fibrinogen, but does lyse fibrin. The optimum pH with TAMe as substrate is 8.8. It may be that thrombin-C is a dimer of the basic structure in thrombin-E.

Spontaneous Hydrolysis of Glycosides

1998 ◽  
Vol 120 (27) ◽  
pp. 6814-6815 ◽  
Author(s):  
Richard Wolfenden ◽  
Xiangdong Lu ◽  
Gregory Young
Keyword(s):  
Spontaneous Hydrolysis ◽  
Hydrolysis Of

scholarly journals Common-type acylphosphatase: steady-state kinetics and leaving-group dependence

1997 ◽  
Vol 327 (1) ◽  
pp. 177-184 ◽  
Author(s):  
Paolo PAOLI ◽  
Paolo CIRRI ◽  
Lucia CAMICI ◽  
Giampaolo MANAO ◽  
Gianni CAPPUGI ◽  
...  
Keyword(s):  
Inorganic Phosphate ◽  
Strong Dependence ◽  
Common Type ◽  
Enzyme Active Site ◽  
Enzyme Substrate ◽  
Linear Relationships ◽  
Steady State Kinetics ◽  
Spontaneous Hydrolysis ◽  
Leaving Group ◽  
Hydrolysis Of

A number of acyl phosphates differing in the structure of the acyl moiety (as well as in the leaving-group pKa of the acids produced in hydrolysis) have been synthesized. The Km and Vmax values for the bovine common-type acylphosphatase isoenzyme have been measured at 25 °C and pH 5.3. The values of kcat differ widely in relation to the different structures of the tested acyl phosphates: linear relationships between log kcat and the leaving group pKa, as well as between log kcat/Km and the leaving-group pKa, were observed. On the other hand, the Km values of the different substrates are very close to each other, suggesting that the phosphate moiety of the substrate is the main chemical group interacting with the enzyme active site in the formation of the enzyme–substrate Michaelis complex. The enzyme does not catalyse transphosphorylation between substrate and concentrated nucleophilic acceptors (glycerol and methanol); nor does it catalyse H218O–inorganic phosphate oxygen exchange. It seems that no phosphoenzyme intermediate is formed in the catalytic pathway. Furthermore, during the enzymic hydrolysis of benzoyl phosphate in the presence of 18O-labelled water, only inorganic phosphate (and not benzoate) incorporates 18O, suggesting that no acyl enzyme is formed transiently. All these findings, as well as the strong dependence of kcat upon the leaving group pKa, suggest that neither a nucleophilic enzyme group nor general acid catalysis are involved in the catalytic pathway. The enzyme is competitively inhibited by Pi, but it is not inhibited by the carboxylate ions produced during substrate hydrolysis, suggesting that the last step of the catalytic process is the release of Pi. The activation energy values for the catalysed and spontaneous hydrolysis of benzoyl phosphate have been determined.

Sign in / Sign up

Export Citation Format

Share Document