Hi, all.
As many of you know, I am the proponent of the Glutathione Depletion--Methylation Cycle Block hypothesis for the pathogenesis and pathophysiology of ME/CFS.
If glutathione depletion coupled with a partial block in the methylation cycle is indeed the core mechanism in the pathophysiology of ME/CFS, then the various abnormalities in ME/CFS must stem from it. In the past, I have been able to find biochemical connections between this basic mechanism and many of the abnormalities in ME/CFS.
One feature of ME/CFS that I have not yet connected to this mechanism is the disruption in the sleep-wake cycle that many PWMEs experience.
Recently I came upon a paper that I think will enable me to make this connection. The abstract is below, and the full paper is available from PubMed.
This paper discusses the presence of a disulfide bridge in the serotonin N-acetyltransferase enzyme molecule. This enzyme catalyzes one of the steps in the conversion of serotonin to melatonin, and this conversion is important in controlling the sleep-wake cycle. Under reducing conditions, the disulfide bridge does not form, and the enzyme can catalyze its reaction. Under oxidizing conditions, when the disulfide bridge forms, the reaction is not catalyzed.
I suggest that if glutathione becomes depleted in the pineal gland, the resulting oxidizing conditions will cause formation of this disulfide bond, shutting off the conversion of serotonin to melatonin, and disrupting the sleep-wake cycle.
If this is true, I think we can expect that if glutathione is brought back up by lifting the partial methylation cycle block using one of the methylation treatment protocols, the sleep-wake cycle abnormalities in ME/CFS should be corrected. I note that some people who have tried this type of treatment have indeed reported improvements in sleep.
Best regards,
Rich
J Biol Chem. 2002 Nov 15;277(46):44229-35. Epub 2002 Sep 4.
An intramolecular disulfide bridge as a catalytic switch for serotonin N-acetyltransferase.
Tsuboi S, Kotani Y, Ogawa K, Hatanaka T, Yatsushiro S, Otsuka M, Moriyama Y.
Source
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Abstract
Serotonin N-acetyltransferase (EC. 2.3.1.87) (AA-NAT) is a melatonin rhythm-generating enzyme in pineal glands. To establish a melatonin rhythm, AA-NAT activity is precisely regulated through several signaling pathways. Here we show novel regulation of AA-NAT activity, in which an intramolecular disulfide bond may function as a switch for the catalysis. Recombinant AA-NAT activity was irreversibly inhibited by N-ethylmaleimide (NEM) in an acetyl-CoA-protected manner. Oxidized glutathione or dissolved oxygen reversibly inhibited AA-NAT in an acetyl-CoA-protected manner. To identify the cysteine residues responsible for the inhibition, AA-NAT was first oxidized with dissolved oxygen, treated with NEM, reduced with dithiothreitol, and then labeled with [(14)C]NEM. Cys(61) and Cys(177) were specifically labeled in an acetyl-CoA-protected manner. The AA-NAT with the Cys(61) to Ala and Cys(177) to Ala double substitutions (C61A/C177A-AA-NAT) was fully active but did not exhibit sensitivity to either oxidation or NEM, whereas the AA-NATs with only the single substitutions retained about 40% of these sensitivities. An intramolecular disulfide bond between Cys(61) and Cys(177) formed upon oxidation and cleaved upon reduction was identified. Furthermore, C61A/C177A-AA-NAT expressed in COS7 cells was relatively insensitive to H(2)O(2)-evoked oxidative stress, whereas wild-type AA-NAT was strongly inhibited under the same conditions. These results indicate that the formation and cleavage of the disulfide bond between Cys(61) and Cys(177) produce the active and inactive states of AA-NAT. It is possible that intracellular redox conditions regulate AA-NAT activity through switching via an intramolecular disulfide bridge.
PMID:
12215431
As many of you know, I am the proponent of the Glutathione Depletion--Methylation Cycle Block hypothesis for the pathogenesis and pathophysiology of ME/CFS.
If glutathione depletion coupled with a partial block in the methylation cycle is indeed the core mechanism in the pathophysiology of ME/CFS, then the various abnormalities in ME/CFS must stem from it. In the past, I have been able to find biochemical connections between this basic mechanism and many of the abnormalities in ME/CFS.
One feature of ME/CFS that I have not yet connected to this mechanism is the disruption in the sleep-wake cycle that many PWMEs experience.
Recently I came upon a paper that I think will enable me to make this connection. The abstract is below, and the full paper is available from PubMed.
This paper discusses the presence of a disulfide bridge in the serotonin N-acetyltransferase enzyme molecule. This enzyme catalyzes one of the steps in the conversion of serotonin to melatonin, and this conversion is important in controlling the sleep-wake cycle. Under reducing conditions, the disulfide bridge does not form, and the enzyme can catalyze its reaction. Under oxidizing conditions, when the disulfide bridge forms, the reaction is not catalyzed.
I suggest that if glutathione becomes depleted in the pineal gland, the resulting oxidizing conditions will cause formation of this disulfide bond, shutting off the conversion of serotonin to melatonin, and disrupting the sleep-wake cycle.
If this is true, I think we can expect that if glutathione is brought back up by lifting the partial methylation cycle block using one of the methylation treatment protocols, the sleep-wake cycle abnormalities in ME/CFS should be corrected. I note that some people who have tried this type of treatment have indeed reported improvements in sleep.
Best regards,
Rich
J Biol Chem. 2002 Nov 15;277(46):44229-35. Epub 2002 Sep 4.
An intramolecular disulfide bridge as a catalytic switch for serotonin N-acetyltransferase.
Tsuboi S, Kotani Y, Ogawa K, Hatanaka T, Yatsushiro S, Otsuka M, Moriyama Y.
Source
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Abstract
Serotonin N-acetyltransferase (EC. 2.3.1.87) (AA-NAT) is a melatonin rhythm-generating enzyme in pineal glands. To establish a melatonin rhythm, AA-NAT activity is precisely regulated through several signaling pathways. Here we show novel regulation of AA-NAT activity, in which an intramolecular disulfide bond may function as a switch for the catalysis. Recombinant AA-NAT activity was irreversibly inhibited by N-ethylmaleimide (NEM) in an acetyl-CoA-protected manner. Oxidized glutathione or dissolved oxygen reversibly inhibited AA-NAT in an acetyl-CoA-protected manner. To identify the cysteine residues responsible for the inhibition, AA-NAT was first oxidized with dissolved oxygen, treated with NEM, reduced with dithiothreitol, and then labeled with [(14)C]NEM. Cys(61) and Cys(177) were specifically labeled in an acetyl-CoA-protected manner. The AA-NAT with the Cys(61) to Ala and Cys(177) to Ala double substitutions (C61A/C177A-AA-NAT) was fully active but did not exhibit sensitivity to either oxidation or NEM, whereas the AA-NATs with only the single substitutions retained about 40% of these sensitivities. An intramolecular disulfide bond between Cys(61) and Cys(177) formed upon oxidation and cleaved upon reduction was identified. Furthermore, C61A/C177A-AA-NAT expressed in COS7 cells was relatively insensitive to H(2)O(2)-evoked oxidative stress, whereas wild-type AA-NAT was strongly inhibited under the same conditions. These results indicate that the formation and cleavage of the disulfide bond between Cys(61) and Cys(177) produce the active and inactive states of AA-NAT. It is possible that intracellular redox conditions regulate AA-NAT activity through switching via an intramolecular disulfide bridge.
PMID:
12215431
