Hi, all.
The above question has been around for quite a few years, and we haven't had a good answer for it. I think it is now possible to answer it, based on some recent research in Korea.
Here's some background: In the 1990's, Drs. Charles Lapp and Paul Cheney initiated treatment of their CFS patients by injection of vitamin B12, after observing that many patients had elevated homocysteine or methylmalonate in urine testing. They found that there was a threshold of response at between 2,000 and 2,500 micrograms per injection to produce an improvement in energy, stamina or wellbeing that lasted for two or three days. Lower dosages did not appear to produce improvements. This was puzzling, because the recommended daily allowance (RDA) for vitamin B12 in adults is only 2.4 micrograms per day. Why did the dosage need to be so high to produce improvement in symptoms?
As many of you know, the sublingual hydroxocobalamin dosage in the Simplified Methylation Protocol today is comparable to the injected dosages that Drs. Lapp and Cheney found to be necessary, still very high compared to the RDA dosage, and this question has remained. (I note that high dosages of B12 are also used in autism, which shares much of the same pathophysiology with ME/CFS.)
O.K., in 2011 a paper was published by two researchers in Korea, Jeong and Kim. The abstract is pasted below.
The research they report was actually done on a bovine (cow) B12-processing complementation group and cyanocobalamin. However, the human complementation group is very similar, and I suspect that the results will also be similar for other forms of B12 than cyanocobalamin.
They studied the CblC complementation group. This is part of the B12 processing pathway that is found inside all cells. When a form of B12 comes into a cell from the blood by the usual transcobalamin route, it is bound to CblC, and its beta ligand (cyano-, methyl-, or adenosyl-) is removed. Then it is sent on to be converted back to methylcobalamin or adenosylcobalamin as needed by the cell.
In order for this processing to happen, the CblC complementation group must first bind the B12 form. The strength of binding is called the affinity (Kd), and it is measured in concentration units. The higher the affinity, the lower the Kd. It turns out that the bare CblC complex has a relatively low affinity for B12, compared to the concentration of B12 in the cells, and this would be unfavorable for the necessary binding, and would tend to lower the reaction rate.
What these researchers found is that normally glutathione binds to CblC, and in doing so, it increases the affinity of CblC for B12. And it does so by a whopping amount--over a factor of a hundred!!
Turning this around, if glutathione becomes depleted, as in ME/CFS and autism, the affinity of CblC for B12 is going to drop substantially. I suggest that the glutathione depletion, combined with its major effect on this affinity, is the reason the B12 dosage must be so high in treating ME/CFS and autism.
Best regards,
Rich
Biochem Biophys Res Commun. 2011 Aug 26;412(2):360-5. Epub 2011 Jul 29.
Glutathione increases the binding affinity of a bovine B?? trafficking chaperone bCblC for vitamin B??.
Jeong J, Kim J.
School of Biotechnology, Yeungnam University, 214-1 Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749, Republic of Korea.
Abstract
Intracellular B(12) metabolism involves a B(12) trafficking chaperone CblC that is well conserved in mammals including human. The protein CblC is known to bind cyanocobalamin (CNCbl, vitamin B(12)) inducing the base-off transition and convert it into an intermediate that can be used in enzyme cofactor synthesis. The binding affinity of human CblC for CNCbl was determined to be K(d)=?6-16 ?M, which is relatively low considering sub-micromolar B(12) concentrations (0.03-0.7 ?M) in normal cells. In the current study, we discovered that the base-off transition of CNCbl upon binding to bCblC, a bovine homolog of human CblC, is facilitated in the presence of reduced form of glutathione (GSH). In addition, GSH dramatically increases the binding affinity for CNCbl lowering the K(d) from 27.1 0.2 to 0.24 0.09 ?M. The effect of GSH is due to conformational change of bCblC upon binding with GSH, which was indicated by limited proteolysis and urea-induced equilibrium denaturation of the protein. The results of this study suggest that GSH positively modulates bCblC by increasing the binding affinity for CNCbl, which would enhance functional efficiency of the protein.
Copyright 2011. Published by Elsevier Inc.
PMID: 21821010
The above question has been around for quite a few years, and we haven't had a good answer for it. I think it is now possible to answer it, based on some recent research in Korea.
Here's some background: In the 1990's, Drs. Charles Lapp and Paul Cheney initiated treatment of their CFS patients by injection of vitamin B12, after observing that many patients had elevated homocysteine or methylmalonate in urine testing. They found that there was a threshold of response at between 2,000 and 2,500 micrograms per injection to produce an improvement in energy, stamina or wellbeing that lasted for two or three days. Lower dosages did not appear to produce improvements. This was puzzling, because the recommended daily allowance (RDA) for vitamin B12 in adults is only 2.4 micrograms per day. Why did the dosage need to be so high to produce improvement in symptoms?
As many of you know, the sublingual hydroxocobalamin dosage in the Simplified Methylation Protocol today is comparable to the injected dosages that Drs. Lapp and Cheney found to be necessary, still very high compared to the RDA dosage, and this question has remained. (I note that high dosages of B12 are also used in autism, which shares much of the same pathophysiology with ME/CFS.)
O.K., in 2011 a paper was published by two researchers in Korea, Jeong and Kim. The abstract is pasted below.
The research they report was actually done on a bovine (cow) B12-processing complementation group and cyanocobalamin. However, the human complementation group is very similar, and I suspect that the results will also be similar for other forms of B12 than cyanocobalamin.
They studied the CblC complementation group. This is part of the B12 processing pathway that is found inside all cells. When a form of B12 comes into a cell from the blood by the usual transcobalamin route, it is bound to CblC, and its beta ligand (cyano-, methyl-, or adenosyl-) is removed. Then it is sent on to be converted back to methylcobalamin or adenosylcobalamin as needed by the cell.
In order for this processing to happen, the CblC complementation group must first bind the B12 form. The strength of binding is called the affinity (Kd), and it is measured in concentration units. The higher the affinity, the lower the Kd. It turns out that the bare CblC complex has a relatively low affinity for B12, compared to the concentration of B12 in the cells, and this would be unfavorable for the necessary binding, and would tend to lower the reaction rate.
What these researchers found is that normally glutathione binds to CblC, and in doing so, it increases the affinity of CblC for B12. And it does so by a whopping amount--over a factor of a hundred!!
Turning this around, if glutathione becomes depleted, as in ME/CFS and autism, the affinity of CblC for B12 is going to drop substantially. I suggest that the glutathione depletion, combined with its major effect on this affinity, is the reason the B12 dosage must be so high in treating ME/CFS and autism.
Best regards,
Rich
Biochem Biophys Res Commun. 2011 Aug 26;412(2):360-5. Epub 2011 Jul 29.
Glutathione increases the binding affinity of a bovine B?? trafficking chaperone bCblC for vitamin B??.
Jeong J, Kim J.
School of Biotechnology, Yeungnam University, 214-1 Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749, Republic of Korea.
Abstract
Intracellular B(12) metabolism involves a B(12) trafficking chaperone CblC that is well conserved in mammals including human. The protein CblC is known to bind cyanocobalamin (CNCbl, vitamin B(12)) inducing the base-off transition and convert it into an intermediate that can be used in enzyme cofactor synthesis. The binding affinity of human CblC for CNCbl was determined to be K(d)=?6-16 ?M, which is relatively low considering sub-micromolar B(12) concentrations (0.03-0.7 ?M) in normal cells. In the current study, we discovered that the base-off transition of CNCbl upon binding to bCblC, a bovine homolog of human CblC, is facilitated in the presence of reduced form of glutathione (GSH). In addition, GSH dramatically increases the binding affinity for CNCbl lowering the K(d) from 27.1 0.2 to 0.24 0.09 ?M. The effect of GSH is due to conformational change of bCblC upon binding with GSH, which was indicated by limited proteolysis and urea-induced equilibrium denaturation of the protein. The results of this study suggest that GSH positively modulates bCblC by increasing the binding affinity for CNCbl, which would enhance functional efficiency of the protein.
Copyright 2011. Published by Elsevier Inc.
PMID: 21821010