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Model Experiments on Oxidative Phosphorylation.

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For nitroxide radicals with
undergo mesomerism, only
nitroxide-nitrogen (and the
boring phenyl nucleus) are
synthetase can be induced by simultaneous addition of
phenylalanine, tyrosine, and tryptophan (multivalent induction) [ * ] .
Corresponding studies with a n alkaloid-producing strain of
C/aviceps paspali gave the following results. The DAHP
synthetase could be separated into three isoenzymes, which
are inhibited by phenylalanine, tyrosine, and tryptophan,
respectively. The last named isoenzyme shows 6 0 % of
the total activity. The concentrated chorismate mutase is
inhibited by phenylalanine or tyrosine; tryptophan activates it. Prephenate dehydrogenase and dehydratase show
allosteric inhibition by tyrosine and phenylalanine, respectively. Anthranilate synthetase is not inhibited by tryptophan W
vinyl or acyl groups that can
the coupling constants of the
phenyl-protons of the neighavailable for comparison. AS
F:?
R’ -C -N - R ~
R Jto R4 = aryl or
R 1 = R3 =
R4 = aryl,
Rl
R2 = CN
=
aryl or methyl
R2 = aryl
would be expected from the steric relations, the coupling
constants of the vinyl-nitroxide radicals (4) studied are
comparable with those of the azomethine-nitroxide radicals
(3a) and (3b), and those of the acyl-nitroxide radicals (5) are
comparable with those of the azomethine-nitroxide radicals
(34.
[VB 82 IE]
Lecture at Hanover (Germany) o n May 11th 1967
German version: Angew. Chem. 79, 825 (1967)
[*] Prof. Dr. F. Lingens
Chemisches Institut der Universitat
Wilhelmstr. 33
74 Tiibingen (Germany)
[ l ] F. Lingens, W. Goebel, and H . Uesseler, Biochem. Z . 346, 357
(1966); Europ. J. Biochem. I , 363 (1967).
[2] F. Lingens, W. Goebel, and H . Uesseler, Naturwissenschaften
54, 141 (1967); Europ. J. Biochem., in press.
Lecture given at Marburg (Germany) on April 28th, 1967 [VB 79 IEI
German version: Angew. Chem. 79,825 (1967)
[*I Doz. Dr. H.
G. Aurich
Chemisches Institut der Universitat
Bahnhofstr. 7
355 Marburg/Lahn (Germany)
Model Experiments on Oxidative Phosphorylation
The Biosynthesis of Aromatic Amino Acids and
its Control
By Tlz. Wieland[*I
Conversion of the free energy of chemical reactions, in the
present case oxidation of bound hydrogen, into the “energyrich” pyrophosphate linkage of adenosine triphosphate
(ATP) by synthesis from adenosine diphosphate (ADP) and
orthophosphate (P) is the fundamental process for the life
of aerobic organisms. This conversion takes place, in some
manner still unknown, in close connection with the “respiration chain” i.e. the organized enzyme system of the mitochondria, in which pyridinium nucfeotide (NAD), flavine
adenine dinucleotide (FAD), (presumably) ubiquinone, and
cytochrome bring electrons of the fuel to oxygen. Since
By F. Lingens I*I
The biosynthetic pathway to aromatic amino acids branches
at chorismic acid ( I ) . By studying the control mechanism of
this biosynthesis by yeast (Saccharomyes cerevisiae), the
following enzymes could be detected and concentrated:
3-deoxy-2-0x0-arabo-heptonicacid 7-phosphate synthetase
(DAHP synthetase) (a), chorismate mutase (b), prephenate
dehydrogenase (c), prephenate dehydratase (d), anthranilate
synthetase (e), and p-aminobenzoate synthetase (f).
YOOH
FOOH
FOOH
c=o
c=o
c=o
b/
COOH
I
C-OP03H2
II
CH2
FHO
H-C-OH
I
H-?-OH
+
COOH
I
c=o
I
y 3 2
HO-C-H
I
H-C-OH
,
LO
QCPH
Trp
- Q0ZOOH
I
H-?-OH
COOH
HO
H
DAHP synthetase could be separated chromatographically
into three isoenzymes, one of which was allosterically inhibited by phenylalanine (Phe) and a second by tyrosine
(Tyr); the third is not inhibited by phenylalanine, tyrosine, or
tryptophan (Trp). Chorismate mutase consists of two isoenzymes, both of which are inhibited by tyrosine; tryptophan
induces and activates this enzyme. Prephenate dehydrogenase
is inhibited by tyrosine; phenylalanine causes both induction and activation. Prephenate dehydratase is inhibited allosterically by phenylalanine and repressed in its
biosynthesis. Anthranilate synthetase is inhibited allosterically by tryptophan and repressed. p-Aminobenzoate
Angew. Chem. internat. Edit. VoI. 6 (1967)
No. 9
COOH
NH2
oxidative phosphorylation can be prevented by SH blocking
agents, the system must contain essential thiol groups in its
structural units. Model experiments on the oxidative conversion of a n energy-poor phosphoric ester linkage into an
energy-rich phosphate linkage have been performed in
several laboratories. For instance, hydroquinone monophosphates, as well as S-alkyl thiophosphates, have been
converted into phosphorylating agents, but oxidative activation of a n inorganic phosphate has not previously been
achieved in a model system. With E. Bauerlein we have found
two classes of compounds that produce oxidative linkage and
activation of phosphate: monothiohydroquinone S-alkyl
ethers ( I ) and thiolactones (2) lead to a 20 to 30 % yield of
ATP on oxidation of a mixture of ADP and P by bromine
811
in an anhydrous medium, e.g. in pyridine. The process is
prevented by presence of 2,4-dinitrophenol, particularly in
the case of compound (2). Thiazolidones (3), in place of the
thiolactone (2), can also produce oxidative phosphorylation
( H . Aqzdu).
Structures such as (2) and (3) (with larger rings) can be
considered to be produced in the tertiary structures of
proteins. The reaction with thiolactone, for which a plausible
mechanism can be formulated, can be conceived as occurring
a t various places in the respiration chain, since the thiolactone could be oxidized, with simultaneous activation of
phosphate, by all oxidizing members of the respiration chain
(DPN, FAD, quinones, oxidized cytochromes).
Lecture at Bonn (Germany) on May 23rd, 1967
[VB 83 IE]
German version: Angew. Chem. 79. 826 (1967)
[*I Prof. Dr. Th. Wieland
Institut fur Organische Chemie der Universitat
Robert-Mayer-Str. 7-9
6 Frankfurt/Main (Germany)
(4)
J
ance with the Woodward-Hoffmann rules leads to cis,transdiacylbutadienes. For instance, the dibenzoyl compound
(5) is converted at 70 OC into the butadiene derivative (6),
and this in a subsequent reaction into the bicyclic compound (7).
Lecture at Marburg (Germany) on May 5th, 1967
[VB 84 IEI
German version: Angew. Chem. 79, 827 (1967)
[*] Priv.-Doz. Dr. G. Maier
Institut fur Organische Chemie der Technischen Hochschule
Richard-Willstatter-Allee
75 Karlsruhe (Germany)
Photochemical Studies of Quinizarin
By H. Labhart [*I
Valence Tautomerism in Heterocyclic Systems
By G. MaierI*l
Valence tautomerism of the type ( I ) 2 (2), where n = 1
or 2, has been described for carbocyclic compounds. We
were interested in the question whether analogous changes
could be realized if carbon atoms 3 and 4 were replaced by
heteroatoms.
Photochemical reaction of quinizarin ( I ) (2x 10-5 molar in
degassed hexane) is often markedly accelerated by the
presence of other substances (10-5 molar), benzophenone
and some quinones being particularly effective. Measurements of the quantum yield as a function of the wavelength
of the incident light have shown that with benzophenone as
accompanying substance the primary step is excitation of
that molecule. However, further reaction does not occur by
sensitization of the triplet state of the quinizarin but, instead,
Various cis-l,2-diacylcyclopropanesand cis-3,4-diacylcyclobutenes [oxidation of hexamethyl(Dewar benzene) by KMn04
were theregives 3,4-diacetyl-l,2,3,4-tetramethylcyclobutene]
fore prepared and converted into cyclic azines by hydrazine.
It transpired that valence-tautomeric relations persist after
introduction of nitrogen atoms. This follows from, for
instance, the temperature-dependence of the N M R spectrum
(3). The
of 1,6-dimethyl-2,5-diphenyl-3,4-diazanorcaradiene
two geminal cyclopropane protons Ha and Hb give two
doublets at room temperature. The resolution is lost on
warming to 7OoC, and at 13OoC a singlet arising from the
two protons appears at a position midway between the
H 3 : T13-~ C6H5
H3C
-A
CISH,
(34
-
H3eh:5A
- .Hb
H3C
C6H5
(4)
H Ha
3 C - vHb, NC&5
[VB 86 IE]
Lecture at Berlin (Germany) on May 8th. 1967
German version: Angew. Chem. 79, 826 (1967)
H3C
[*I Prof. Dr. H. Labhart
--N
C6H5
(3b)
positions of the original signals. These changes are reversible
and indicate the valence-tautomeric equilibrium (3u) S (4)
(3b), which lies entirely o n the bicyclic side.
Heating the diacylcyclobutenes also gives products that have
been identified. If the reactions occurred in the manner of a
Cope rearrangement with participation of two carbonyl
groups, cyclic peroxides would be formed, but that is not the
case. In the first step, stereospecific ring-opening in accord-
8 12
solvent radicals L - , which are first formed by hydrogen
abstraction, react with quinizarin to give the photoproducts
that are identified mass-spectrometrically. The U V spectrum
of these products is very similar to that of 2,3-dihydroquinizarin. It is most probable that the compounds (2) and
(3) are formed.
Physikalisch-Chemisches Institut der Universitiit
Ramistr. 76
CH-8001 Zurich (Switzerland)
Periodates
By H . Siebertr'l
From the reactions of alkaline periodate solutions it can be
concluded that they contain binuclear anions [H21201014Crystal structure analysis of the salt K4H212010.8H20
showed that the anion consists of two 1 0 6 octahedra with a
Angew. Clzem. internut. Edit. 1 Yof.6 (1967) / No. 9
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