Liver acetone powder

Enantioselective enzymatic ester hydrolyses of prochiral trimethylsilyl-substituted diesters of the malonate type have been applied for the synthesis of the related optically active monoesters68. As an example of this particular type of biotransformation, the enantioselective conversion of the diester 82 is illustrated in Scheme 17. Hydrolysis of compound 82 in phosphate buffer, catalyzed by porcine liver esterase (PLE E.C. 3.1.1.1) or horse liver acetonic powder (HLAP), gave the optically active monoester 83 (absolute configuration not reported) in 86% and 49% yield, respectively. The enantiomeric purities... 

Asymmetric reduction of the ketone on a 1.0-g (4.0-mmol) scale to provide (R)-(-)-2,2-diphenylcyclopentanol (96% ee) has been reported employing (+)-( -chlorodiisopinocampheylborane however, the reaction is extremely slow and inefficient [70% yield, 5 days, 2.6 equiv of (+)-p-chlorodiisopinocampheylborane].5 Other efforts to obtain enantiomerically pure 1 by means of enzymatic hydrolysis of the corresponding racemic acetates using horse liver acetone powder (HLAP) and pig... 

The sources of enzyme assayed were an extract of rabbit liver acetone powder and an extract of baker s yeast. 

Acetone Powder Containing Esterase Activity. The main advantage in using crude homogenates or acetone powders of organs such as liver is to have a cheap source of different enzymes. If one of these is desired for a specific substrate, the crude enzymatic mixture can be used with some advantage, compared to the purified enzymes. Pig liver acetone powder (PLAP), together with other extracts, is commercially available or can be prepared from fresh pig liver. PLAP has been used for the enantioselective hydrolysis of the racemic acetate of rrans-2-phenylcyclohexanol... 

The acetates of 1-arylalkan-l-ols were successfully resolved by acetone powders (PLAP and goat liver acetone powder, GLAP) containing esterase activity (eq 12). ... 

An interesting application of the esterase activity of horse liver acetone powder (HLE) has been the enantioselective hydrolysis of racemic lactones. The powder proved to be more effective than PLE in this hydrolysis, from which the unreacted lactone was recovered with high enantiomeric excess. The process seems more effective for S and medium size lactones (eq 13). ... 

The use of ester hydrolase preparations such as pig liver esterase (PLE) or pig liver acetone powder (PLAPy complements reduction approaches for the synthesis of enantio-enriched alcohols. 

Source Acetone powder from beef liver Catalase fraction from beef liver Acetone powder from beef liver... 

This chiral alcohol (—)-l can be obtained from racemic I by conversion to the chloroacetate (reaction with CICH2COOH), which is saponified by enzyme Pl.AP (pig liver acetone powder) at 40% conversion to give (—)-l and the (+)-estcr, which can then be saponified to provide (+)-l. 

This chiral alcoh chloroacetate (reactio liver acetone powder then be saponified to This alcohol whei asymmetric induction less effective than 8- ... 

Pig pancreatic lipase added to a mixture of ethyl butyrate, ethyl isobutyrate, and ethyl pivalate in phosphate buffer (pH 8), and quenched with 10 M NaOH when reaction complete (pH-stat method) - butyric acid. Y 65% (> 95% purity). The enzyme only hydrolyzed straight-chain esters. F.e., preferential cleavage of functionalized esters, and comparison with horse liver acetonic powder, s. B. De Jeso et al., Synth. Commun. 18, 1699-705 (1988) preferential hydrolysis of dicarboxylic acid esters s. ibid. 1691-7. 

Synthesis of theanine by pigeon liver acetone powder extract. Agric. Biol. Chem. 28, 325 (1964). 

The first simple method using isotopic labelling has been developed to confirm the actual and observed selectivities in the enzymatic hydrolysis of unsymmetrical diacetates and to measure the enzyme selectivity efficiency. The simple method consists of enzymatic hydrolysis of the unsymmetrical diacetate followed by labelling of the hydroxyacetate formed with CD3CO2D-DCC and enzymatic rehydrolysis of the labelled compound under identical reaction conditions. The amount of label lost, as determined by H NMR spectroscopy, directly indicates the extent of regioselective action of the enzyme. For example, enzymic hydrolysis using pig liver acetone powder (FLAP) of the racemic glycerol diacetate (208) yielded a mixture (1 9) of the 1-hydroxy ester (209) and the 2-hydroxy ester (210). Isolation of the 2-hydroxy... 

Sallach observed the presence of a serine-hydroxypyruvate transaminase in liver and kidney of a number of mammalian species and partiaUy purified the enzyme from dog liver acetone powder. Alanine and pyruvate were specific for the transamination reaction, and transamination was shown to be reversible and to proceed in either direction by incubating serine with pyruvate or hydroxypyruvate with alanine. 

Most of these catal3rsts are relativdy nonspecific and will attack other pyrophosphate-containing compounds. Snake venom 17J ) and potatoes 175) have been foimd to be extremely good sources of enzymes which will act on both the oxidized and reduced forms of DPN and TPN. Jacobson and Kaplan (176) have purified an enzyme from pigeon liver acetone powder which cleaves the pyridine coenzymes at the pyrophosphate linkage. It is of interest that this catalyst reacts only with the reduced and not the oxidized forms of DPN and TPN. However, the enzyme cleaves the oxidized a-isomer of DPN 177), whereas it does not cleave the enzymically active 9-isomer 176). The specificity of the enzyme appears to be due to the structure of the nucleotides rather than to the positive chaige of the pyridine nitrogen. 

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