[PA Engineer]

Pantothenic Acid is a precursor to the sulfur cycle. Pantothenate kinase (4 different depending on body systems) is required for conversion to 4-phosphopantothenic acid for the actual entry into the cycle. From there the dominate reaction with cysteine is 4'-phosphopantothenolyl-l-cysteine and then 4-phosphopantetheine. This is the point where exogenous pantetheine enters the cycle via pantetheine kinase.

For reference, pantethine is the dysulfide bond of panteheine. Pantetheine and/or 4'-phosphopantetheine is converted by pantetheine-phospateadenylytransferase to dephosnpho-coenzyme A. The reaction then involves the protein dephospho-Coa kinase to convert to Coenzyme A. After CoA the diminutive reactions breakdown CoA to pantetheine again and then to Cysteamine via vanin proteins. From there cysteamine is converted via cysteamine deoxygenase to hypotaurine. Hypotaurine dehydrogenase converts hypotaurinte to taurine (bidirectional)

Pantetheine can also renter the cycle before the conversion to cysteamine.

That is one side of the cycle.

It is a bit complicated and autocorrect spelling makes it worse and me ready to hit the bed.

B5 is the feedstock as well as cysteine.

Complicated, however any breakdown in the cycle leads to many varied disease states including negative outcomes with viral infection and cancer.

Best.

[gleeaikin]

Thank you for the very detailed information. It sounds a little like the complexities of the Krebs Cycle, which I once included in Congressional testimony 48 years ago when the government was trying to turn vitamins into over the counter drugs and increase the price three-fold or more. This was an issue that had people in both parties up in arms.