|
Title
Cytosolic and mitochondrial systems for NADH- and NADPH-dependent
reduction of alpha-lipoic acid.
Author
Haramaki N; Han D; Handelman GJ; Tritschler HJ; Packer L
Address
Department of Molecular and Cell Biology, University of California
at
Berkeley 94720-3200, USA.
Source
Free Radic Biol Med, 22(3):535-42 1997
Abstract
In cellular, tissue, and organismal systems, exogenously supplied
alpha-lipoic acid (thioctic acid) has a variety of significant
effects, including direct radical scavenging, redox modulation
of cell metabolism, and potential to inhibit oxidatively-induced
injury. Because reduction of lipoate to dihydrolipoate is a crucial
step in many of these processes, we investigated mechanisms of
its reduction. The mitochondrial NADH-dependent dihydrolipoamide
dehydrogenase exhibits a marked preference for R(+)-lipoate,
whereas NADPH-dependent glutathione reductase shows slightly
greater activity toward the S(-)-lipoate stereoisomer. Rat liver
mitochondria also reduced exogenous lipoic acid. The rate of
reduction was stimulated by substrates which increased the NADH
content of the mitochondria, and was inhibited by methoxyindole-2-carboxylic
acid, a dihydrolipoamide dehydrogenase inhibitor. In rat liver
cytosol, NADPH-dependent reduction was greater than NADH, and
lipoate reduction was inhibited by glutathione disulfide. In
rat heart, kidney, and brain whole cell-soluble fractions, NADH
contributed more to reduction (70-90%) than NADPH, whereas with
liver, NADH and NADPH were about equally active. An intact organ,
the isolated perfused rat heart, reduced R-lipoate six to eight
times more rapidly than S-lipoate, consistent with high mitochondrial
dihydrolipoamide dehydrogenase activity and results with isolated
cardiac mitochondria. On the other hand, erythrocytes, which
lack mitochondria, somewhat more actively reduced S- than R-lipoate.
These results demonstrate differing stereospecific reduction
by intact cells and tissues. Thus, mechanisms of reduction of
alpha-lipoate are highly tissue-specific and effects of exogenously
supplied alpha-lipoate are determined by tissue glutathione reductase
and dihydrolipoamide dehydrogenase activity.
Title
Effect of DL alpha-lipoic acid on some carbohydrate metabolising
enzymes in stone forming rats.
Author
Jayanthi S; Jayanthi G; Varalakshmi P
Address
Department of Medical Biochemistry, University of Madras, India.
Source
Biochem Int, 25(1):123-36 1991 Sep
Abstract
DL alpha-lipoic acid has been shown to prevent the induced precipitation
of calcium oxalate crystals in the renal tissues of laboratory
animals. The acid seems to have a profound influence on carbohydrate
metabolism in diabetic rats. Here the effect of alpha-lipoic
acid was studied on certain key carbohydrate metabolising enzymes
in the tissues of calcium oxalate stone forming rats administered
with glycollate as oxalate precursor. There was augmentation
of glycolysis in the renal tissues of stone forming as well as
lipoate administered rats. The two major gluconeogenic enzymes,
glucose-6-phosphatase (G6P) and fructose-1, 6 diphosphatase (FDP)
were significantly inhibited in tissues of calculogenic rats.
lipoic acid also reduced the enzyme activities significantly.
The citric acid cycle enzymes were not influenced to an appreciable
extent. The observed alterations are likely to be due to the
regulatory effects of oxalate and lipoate on the enzyme systems.
Title
Relationship between glutathione and DL alpha-lipoic acid againstcadmium-induced
hepatotoxicity.
Author
Sumathi R; Baskaran G; Varalakshmi P
Address
Department of Medical Biochemistry, Dr. ALM Post Graduate Institute
of Basic Medical Sciences, University of Madras, India.
Source
Jpn J Med Sci Biol, 49(2):39-48 1996 Apr
Abstract
cadmium, a divalent metal toxicant, preferentially localizes
in hepatocytes and causes liver injury. DL alpha-lipoic acid
is a dithiol which is effective in rendering protection against
cadmium-associated liver damage, by virtue of its two sulfhydryl
moieties. lipoate was administered to cadmium-exposed rats which
were either prior administered with buthionine sulfoximine to
deplete liver glutathione or not. During lipoate treatment, significant
protection was rendered against cadmium toxicity even under glutathione-depleted
experimental condition. This highlights the antioxidant property
of lipoic acid and its efficacy in mitigating cadmium-associated
liver assault even in the absence of glutathione synthesis.
Title
Relationship between glutathione and DL alpha-lipoic acid against
cadmium-induced hepatotoxicity.
Author
Sumathi R; Baskaran G; Varalakshmi P
Address
Department of Medical Biochemistry, Dr. ALM Post Graduate Institute
of Basic Medical Sciences, University of Madras, India.
Source
Jpn J Med Sci Biol, 49(2):39-48 1996 Apr
Abstract
cadmium, a divalent metal toxicant, preferentially localizes
in hepatocytes and causes liver injury. DL alpha-lipoic acid
is a dithiol which is effective in rendering protection against
cadmium-associated liver damage, by virtue of its two sulfhydryl
moieties. lipoate was administered to cadmium-exposed rats which
were either prior administered with buthionine sulfoximine to
deplete liver glutathione or not. During lipoate treatment, significant
protection was rendered against cadmium toxicity even under glutathione-depleted
experimental condition. This highlights the antioxidant property
of lipoic acid and its efficacy in mitigating cadmium-associated
liver assault even in the absence of glutathione synthesis.
Title
alpha-lipoic acid dependent regeneration of ascorbic acid from
dehydroascorbic acid in rat liver mitochondria.
Author
Xu DP; Wells WW
Address
Department of Biochemistry, Michigan State University, East Lansing
48824, USA.
Source
J Bioenerg Biomembr, 28(1):77-85 1996 Feb
Abstract
Rat liver mitochondria were examined for their ability to reduce
dehydroascorbic acid to ascorbic acid in an alpha-lipoic acid
dependent or independent manner. The alpha-lipoic acid dependent
reduction was stimulated by factors that increased the NADH dependent
reduction of alpha-lipoic acid to dihydrolipoic acid in coupled
reactions. Optimal conditions for dehydroascorbic acid reduction
to ascorbic acid were achieved in the presence of pyruvate, alpha-lipoic
acid, and ATP. Electron transport inhibitors, rotenone and antimycin
A, further enhanced the dehydroascorbic acid reduction. The reactions
were strongly inhibited by 1 mM iodoacetamide or sodium arsenite.
Mitoplasts were qualitatively similar to intact mitochondria
in dehydroascorbate reduction activity. Pyruvate dehydrogenase
and alpha-ketoglutarate dehydrogenase reduced dehydroascorbic
acid to ascorbic acid in an alpha-lipoic acid, coenzyme A, and
pyruvate or alpha-ketoglutarate dependent fashion. Dehydroascorbic
acid was also catalytically reduced to ascorbic acid by purified
lipoamide dehydrogenase in an alpha-lipoic acid (K0.5 = 1.4 +/-
0.8 mM) and lipoamide (K0.5 = 0.9 +/- 0.3 mM) dependent manner.
Title
Preparations of alpha-lipoic acid: the dynamics of their content
in the blood and their effect on hemostasis in lesions of the
human liver
Author
Loginov AS; Nilova TV; Bendikov EA; Petrakov AV
Source
Farmakol Toksikol, 53(2):47-50 1990 Mar-Apr
Abstract
The changes in blood coagulating activity before and after treatment
with alpha-lipoic acid drugs as compared with blood lipoic acid
content were studied in 130 patients with chronic diffuse diseases
of the liver of the virus and alcohol etiology. A moderate correlation
between the increase in blood alpha-lipoic acid concentration
in patients with the liver diseases during the replacement therapy
with alpha-lipoic acid drugs and a number of parameters of thrombelastogram
was established. It was shown that relief of coenzyme deficit
against the background of treatment with lipoic acid is associated
with relief of hypocoagulative syndrome and an elevation of the
blood ATP level. It is suggested that the ability of the coenzyme
to stimulate the bioenergetic protection of hemostasis processes
plays the important role in the mechanism of action of alpha-lipoic
acid drugs.
Title
Alpha-lipoic acid supplementation prevents symptoms of vitamin
E deficiency.
Author
Podda M; Tritschler HJ; Ulrich H; Packer L
Address
Department of Molecular and Cell Biology, University of California
at Berkeley, 94720-3200.
Source
Biochem Biophys Res Commun, 204(1):98-104 1994 Oct 14
Abstract
alpha-lipoic acid, an essential cofactor in mitochondrial dehydrogenases,
has recently been shown to be a potent antioxidant in vitro,
as well as being capable of regenerating vitamin E in vitro.
In this study, using a new animal model for rapid vitamin E deficiency
in adult animals and a new technique for tissue extraction of
oxidized and reduced alpha-lipoic acid, we examined the antioxidant
action of alpha-lipoic acid in vivo. Vitamin E-deficient adult
hairless mice displayed obvious symptoms of deficiency within
five weeks, but if the diet was supplemented with alpha-lipoic
acid the animals were completely protected. At five weeks on
a vitamin E-deficient diet animals exhibited similar decreases
in tissue vitamin E levels, whether supplemented or unsupplemented
with alpha-lipoic acid: vitamin E levels in liver, kidney, heart,
and skin decreased 70 to 85%; levels in brain decreased only
25%. These data show that there was no effect of alpha-lipoic
acid supplementation on vitamin E tissue concentrations, arguing
against a role for alpha-lipoic acid in regenerating vitamin
E in vivo.
Title
Pharmacokinetics of preparations of lipoic acid and their effect
on ATP synthesis, processes of microsomal and cytosol oxidation
in hepatocytes in liver damage in man
Author
Loginov AS; Nilova TV; Bendikov EA; Petrakov AV
Source
Farmakol Toksikol, 52(4):78-82 1989 Jul-Aug
Abstract
The features of the pharmacokinetics of preparations of alpha-lipoic
acid (lipoic acid, thioctacide) as compared with their pharmacodynamic
effects were studied in 125 patients with chronic diffuse diseases
of the liver of viral and alcohol etiology. After a single administration
of the preparations, the authors found an elevation of the maximal
blood concentrations and an increase of alpha-lipoic acid elimination
half-life in patients with liver cirrhosis as compared with chronic
hepatitis patients. During the replacement therapy and elimination
of alpha-lipoic acid deficiency by using the preparations containing
lipoic acid, there is commonly an increase ATP content, an elevation
of functioning mass of hepatocytes and activation of liver detoxifying
function according to the data of the tests of galactose cytosol
oxidation, microsomal oxidation of antipyrine and conjugation
of bilirubin.
Title
Effect of DL alpha-lipoic acid on tissue lipid peroxidation and
antioxidant systems in normal and glycollate treated rats.
Author
Sumathi R; Jayanthi S; Kalpanadevi V; Varalakshmi P
Address
Department of Medical Biochemistry, Dr. A. L. Mudaliar Post Graduate
Institute of Basic Medical Sciences, Taramani, University of
Madras, India.
Source
Pharmacol Res, 27(4):309-18 1993 May-Jun
Abstract
The cytoprotective activity of alpha-lipoic acid against free
radical toxicity, manifested during experimental hyperoxaluria,
has been investigated. Glycollate was used as the inducer of
oxalate hyperoxaluria in rats. The increase in lipid peroxidation
and superoxide dismutase (SOD) activity, associated with a decrease
in catalase activity and glutathione (GSH) level, are the salient
features observed in tissues of hyperoxaluric rats. Free radical
toxicity in the glycollate fed rats is effectively counteracted
by lipoic acid administration. lipoic acid administration brought
about a significant decrease in peroxidative levels with an increase
in catalase activity and glutathione level. These observations
highlight the antioxidant property of alpha-lipoic acid and its
cytoprotective action against experimental hyperoxaluria.
Title
Protective effects of DL-alpha-lipoic acid on cadmium-induced
deterioration of rat hepatocytes.
Author
Müller L
Address
Institute of Toxicology, University of Düsseldorf, F.R.G.
Source
Toxicology, 58(2):175-85 1989 Oct 2
Abstract
The suitability of DL-alpha-lipoic acid (LA) to serve as an antidote
in cadmium (Cd) toxicity in rat hepatocytes was investigated.
Isolated hepatocytes were exposed to 200 and 450 microM Cd in
the presence of 0.2, 1.0 and 5.0 mM LA, respectively. After 30
min of incubation various criteria of cell viability were monitored.
lipoic acid markedly diminished Cd uptake. Concomitantly, Cd-induced
membrane injury, as reflected by the leakage of aspartate aminotransferase
and sorbitol dehydrogenase (SDH) was decreased. Moreover, LA
protected against intracellular toxic responses to Cd, such as
a decrease in cellular SDH activity, a decrease in cellular acid
soluble thiols, especially in total glutathione, a decrease in
cellular urea and an increase in thiobarbituric acid (TBA) reactants,
as a measure of lipid peroxidation. Most protective effects were
seen in hepatocytes challenged with the lower Cd concentration
and coincubated with 5 mM LA. In contrast, at 450 microM Cd even
the highest LA concentration applied either did only reverse
Cd-effects incompletely (SDH-response, TBA-reactants) or did
not protect at all (Cd uptake, enzyme leakage, loss of glutathione).
The data indicate that DL-alpha-lipoic acid serves as a protective
tool against Cd-induced membrane damage and cell dysfunction
in hepatocytes. This stands as long as Cd exposure is low enough
to permit interaction with LA prior to interaction with cell
structures.
Title
Influence of alpha-lipoic acid on intracellular glutathione in
vitro and in vivo.
Author
Busse E; Zimmer G; Schopohl B; Kornhuber B
Address
Abteilung für Hämatologie und Onkologie, Johann Wolfgang
Goethe-Universität, Frankfurt/Main Fed. Rep. of Germany.
Source
Arzneimittelforschung, 42(6):829-31 1992 Jun
Abstract
The influence of alpha-lipoic acid (CAS 62-46-4) on the amount
of intracellular glutathione (GSH) was investigated in vitro
and in vivo. Using murine neuroblastoma as well as melanoma cell
lines in vitro, a dose-dependent increase of GSH content was
observed. Dependent on the source of tumor cells the increase
was 30-70% compared to untreated controls. Normal lung tissue
of mice also revealed about 50% increase in glutathione upon
treatment with lipoic acid. This corresponds with protection
from irradiation damage in these in vitro studies. Survival rate
of irradiated murine neuroblastoma was increased at doses of
100 micrograms lipoic acid/d from 2% to about 10%. In agreement
with the in vitro studies, in vivo experiments with whole body
irradiation (5 and 8 Gy) in mice revealed that the number of
surviving animals was doubled at a dose of 16 mg lipoic acid/kg.
Improvement of cell viability and irradiation protection by the
physiological compound lipoic acid runs parallel with an increase
of intracellular GSH/GSSG ratio.
Title
Hepatic lipoate uptake.
Author
Peinado J; Sies H; Akerboom TP
Address
Institut für Physiologische Chemie I, Universität Düsseldorf,
West Germany.
Source
Arch Biochem Biophys, 273(2):389-95 1989 Sep
Abstract
Uptake of [35S]lipoate was studied in perfused rat liver and
in isolated rat hepatocytes. During single-pass perfusion of
[35S]lipoate about 30% of the radioactivity is retained in the
liver. A substantial amount of 5,5'-dithiobis(2-nitrobenzoic
acid)-reactive material appears in the effluent perfusate, while
hepatic efflux of GSH is unchanged. The hepatic uptake of lipoate,
the release of thiols, and also the biliary excretion of 35S-labeled
compounds are suppressed by octanoate. In isolated hepatocytes
the uptake of lipoate follows saturation kinetics showing a Km
value of 38 microM and a Vmax of 180 pmol/mg X 10 s. The uptake
is temperature-dependent; from the Arrhenius plot an activation
energy of 14.8 kcal/mol at 20 microM lipoate is calculated. At
high concentrations of lipoate (above 75 microM) a nonsaturable
uptake component becomes predominant. lipoate uptake is selectively
inhibited by medium-chain fatty acids. Only slight inhibition
is seen in the presence of long-chain fatty acids, and there
is no inhibition with acetate or lactate. Substantial inhibition
is also observed with acetylsalicylic acid, but not with taurocholate,
bromosulfophthalein or biotin. lipoate uptake can be inhibited
by high concentrations of phloretin (200 microM) and is rather
insensitive to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid
(200 microM). The results indicate that hepatic uptake of lipoate
at physiological concentrations is largely carrier-mediated.
Title
Studies on the efficacy of lipoate and dihydrolipoate in the
alteration of cadmium2+ toxicity in isolated hepatocytes.
Author
Müller L; Menzel H
Address
Institute of Toxicology, University of Düsseldorf, F.R.G.
Source
Biochim Biophys Acta, 1052(3):386-91 1990 May 22
Abstract
lipoate (thioctic acid) is presently used in therapy of a variety
of diseases such as liver and neurological disorders. However,
nothing is known about the efficacy of lipoate and its reduced
form dihydrolipoate in acute cadmium (Cd2+) toxicity which involves
severe liver disturbances. Therefore, we investigated the effects
of these redox compounds on Cd2(+)-induced injuries in isolated
rat hepatocytes. The cells were coincubated with 150 microM Cd2+
and either 1.5-6.0 mM lipoate or 17-89 microM dihydrolipoate
for up to 90 min and Cd2+ uptake as well as viability criteria
were monitored. Both exposure regimens diminished Cd2+ uptake
in correspondence to time and concentration. They also ameliorated
Cd2(+)-induced cell deterioration as reflected by the decrease
in Cd2(+)-induced membrane damage (leakage of aspartate aminotransferase),
by the lessening of the Cd2(+)-stimulated lipid peroxidation
(TBA-reactants) and by the increase in Cd2(+)-depleted cellular
glutathione (GSH + 2 GSSG). Half-maximal protection was achieved
at molar ratios of 9.9 to 19 (lipoate vs. Cd2+) and 0.25 to 0.74
(dihydrolipoate vs. Cd2+), indicating a 19.5 to 50.6 lower protective
efficacy of lipoate as compared to dihydrolipoate. lipoate induced
an increase in extracellular acid-soluble thiols different from
glutathione. It is suggested that dihydrolipoate primarily protects
cells by extracellular chelation of Cd2+, whereas intracellular
reduction of lipoate to the dihydro-compound followed by complexation
of both intra- and extracellular Cd2+ contributes to the amelioration
provided by lipoate.
Title
Experimental substantiation of the method of pharmaco-metabolic
brain protection against hypoxia in severe craniocerebral injury
Author
Rozanov VA; Tsepkolenko VA; Levitskii MV; Galich IM; Rozanov
AIa;
Korol' AP; Nasibullin BA
Source
Fiziol Zh, 37(5):3-11 1991 Sep-Oct
Abstract
The experiment has shown that a complex of functionally related
vitamins including thiamine, lipoate, D-pantothenate, nicotinate
and riboflavine in "pyruvate-dehydrogenase" ratios
decreases inhibition of the activity of alpha-keto acid dehydrogenases
in the brain and liver with thiopental anesthesia, intensifies
arrival of [35S]-lipoate to the brain and decreases acute toxicity
of sodium thiopental (TnNa). The same complex (where thiamine,
pantothenate and riboflavine are substituted by the corresponding
coenzyme forms) complemented by the components stimulating the
function of GABA-bypath of the brain as administered to rats
with serious craniocerebral injury on the background of prolonged
anaesthesia effect improves recovery of the brain functions,
that is followed by normalization of ketoglutarate-dehydrogenase
activity, maintenance of GABA-bypath function and by a decrease
of GABA and glutamate content in the brain. The results obtained
substantiate the advisability to use vitamin-coenzyme-metabolic
complex in the acute period of traumatic brain disease aimed
to increase efficiency of the antihypoxic TnNa effect and to
correct its undesirable effects.
Title
Interaction of functionally coupled vitamins in the distribution
and metabolism of [14C]nicotinic acid in tissues and blood cells
Author
Rozanov AIa; Iakubik EIu
Source
Biokhimiia, 50(9):1399-405 1985 Sep
Abstract
Leucocytes adsorb by two orders of magnitude more labeled nicotinic
acid ([14C]Na) than erythrocytes (as calculated on a per cell
basis). The dynamics of binding of labeled vitamin by leucocytes
is biphasic with the formation of predominantly [14C]nicotinic
coenzymes already at very short time intervals after their injection
to rats. Simultaneous injections of thiamine, riboflavin, lipoate
and pantotenate increased the level of total labeled nicotinate
metabolites in the blood and leucocytes 2.1- and 4.1-fold, respectively.
The metabolism of subcutaneously injected [14C]NA was predominantly
localized in the digestive system with a markedly pronounced
two-phase dynamics of changes of the level of total labeled metabolites
in the liver and small intestine concomitant with their secretion
together with digestive juices. The functionally coupled vitamins
injected simultaneously sharply increased the incorporation of
the total label into liver tissues (up to 45% of the injected
dose against 33% in the control) and the increase in the level
of [14C]pyridine nucleotides. Similar effects were observed upon
accumulation of labeled metabolites of [14C]NA in small intestine
membranes. The increase in the maximal accumulation of nicotinate
under effects of other group B vitamins in brain, heart and spleen
tissues correlated with the dynamics, of their accumulation in
the blood. In the postmaximal period in cardiac muscle and brain
tissues, the second increase in the [14C]NA binding correlated
with the dynamics of its accumulation in the digestive system.(ABSTRACT
TRUNCATED AT 250 WORDS)
Title
The association of the autoantigens of primary biliary cirrhosis
with the mitochondrial H+-ATPase--a reassessment.
Author
Sudoyo H; Noer AS; Mackay IR; Marzuki S
Address
Department of Biochemistry, Monash University, Clayton, Victoria,
Australia.
Source
Biochem Int, 18(5):951-60 1989 May
Abstract
The claimed association between the M2 autoantigens of primary
biliary cirrhosis (PBC) and the mitochondrial H+-ATPase has been
re-examined in view of the recent reports that PBC autoantibodies
react specifically with the lipoate acetyl transferases of 2-oxo
acid dehydrogenases. Study of F0F1-ATPase purified from human
and yeast mitochondria, and the comparison between immunoprecipitates
obtained with antibodies against the H+-ATPase beta subunit and
anti-M2 antibodies of PBC, established that the M2 antigens are
not associated with the H+-ATPase complex. The M2 antigens did
copurify with a crude bovine heart F1-ATPase preparation, but
not with F1-ATPase from yeast, human heart or human liver.
Title
Enzymic synthesis of the iron-sulfur cluster of spinach ferredoxin.
Author
Pagani S; Bonomi F; Cerletti P
Source
Eur J Biochem, 142(2):361-6 1984 Jul 16
Abstract
A biologically active spinach ferredoxin was reconstituted from
the apoprotein by incubation with catalytic amounts of the sulfurtransferase
rhodanese in the presence of thiosulfate, reduced lipoate and
ferric ammonium citrate. Analytical and spectroscopical features
of the reconstituted ferredoxin were identical to those of the
native one; yield of the reconstitution reaction was 80%. Yields
and kinetic parameters of the enzymic and chemical reconstitution
were also compared. The higher efficiency of the enzymic system
is ascribed to a productive interaction between rhodanese and
apoferredoxin favouring the process of cluster build-up and insertion.
The physiological relevance of this synthetic activity is discussed.
Title
Component X. An immunologically distinct polypeptide associated
with mammalian pyruvate dehydrogenase multi-enzyme complex.
Author
De Marcucci O; Lindsay JG
Source
Eur J Biochem, 149(3):641-8 1985 Jun 18
Abstract
The mammalian pyruvate dehydrogenase multi-enzyme complex contains
a tightly-associated 50 000-Mr polypeptide of unknown function
(component X) in addition to its three constituent enzymes, pyruvate
dehydrogenase (E1), lipoate acetyltransferase (E2) and lipoamide
dehydrogenase (E3) which are jointly responsible for production
of CoASAc and NADH. The presence of component X is apparent on
sodium dodecyl sulphate/polyacrylamide gel analysis of the complex,
performed in Tris-glycine buffers although it co-migrates with
the E3 subunit on standard phosphate gels run under denaturing
conditions. Refined immunological techniques, employing subunit-specific
antisera to individual components of the pyruvate dehydrogenase
complex, have demonstrated that protein X is not a proteolytic
fragment of E2 (or E3) as suggested previously. In addition,
anti-X serum elicits no cross-reaction with either subunit of
the intrinsic kinase of the pyruvate dehydrogenase complex. Immune-blotting
analysis of SDS extracts of bovine, rat and pig cell lines and
derived subcellular fractions have indicated that protein X is
a normal cellular component with a specific mitochondrial location.
It remains tightly-associated with the 'core' enzyme, E2, on
dissociation of the complex at pH 9.5 or by treatment with 0.25
M MgCl2. This polypeptide is not released to any significant
extent from E2 by p-hydroxymercuriphenyl sulphonate, a reagent
which promotes dissociation of the specific kinase of the complex
from the 'core' enzyme. Incubation of the complex with [2-14C]pyruvate
in the absence of CoASH promotes the incorporation of radio-label,
probably in the form of acetyl groups, into both E2 and component
X. |
|
Return to Main Page
