This is extremely interesting.
The haem-centered NOS catalysis (hypothesized to be the back-up reaction) needs BH4 but also FAD and FMN (both vit B2).
The adenosylcobalamin reaction also needs BH4.
But for this second (or first) path to work you would need tetrahydrobiopterin in proportion to adenosylcobalamin.
Where do you find this? Is it easily depleted by taking adenosylcobalamin?
Or is there a recycling mechanism (dependent on?)?
"
Defects in the regeneration of the cofactor tetrahydobiopterin (BH4) account for a small fraction of PKU cases. Such cases are sometimes identified as "malignant" PKU, because of the progressive deterioration in neurological function which cannot be alleviated by simple dietary restriction in phenylalanine intake. These cases may be distinguished from the classical form of PKU which is due to a defect in the enzyme phenylalanine hydroxylase (PAH). There are several possible causes of a defect in biopterin metabolism, and the consequences of such a defect can be profound, extending beyond phenylketonuria to defects in neurotransmission. Such cases can be better understood by referring to the biosynthetic pathway of tetrahydrobiopterin:".....
http://www.uic.edu/classes/phar/phar332/Clinical_Cases/aa metab cases/PKU Cases/bioh4.htm
It could be that the tetrahydrobiopterin is missing, not the adenosylcobalamin. Or both. Or first the one (lack of adenosylcobalamin) then resorting to the first reaction (inducing a lack of B2) then a total crash if there is no more BH4?
Since tetrahydrobiopterin is needed to get rid of phenylalanine, and the modern diet is overwhelming us with that, and that it is needed for making adrenalin (which we consume at an alarming rate through stress and our way of life) it could very well be that there are much more people suffering from BH4 deficiency that thought previously.
Fake Folates poisoning:
- sweeteners elevate phenylalanine
- MSG causes dopamine expenditure.
From both ends leading to BH4 deficiency.
How come changing the diet is not sufficient? Maybe BH4 deficiency is a life-saving adaptation. Maybe the body goes in another mode for survival? And stays there? An epigenetic switch?
Enough for today and many thanks Freddd for bringing this up!