Based on these data, the BH4 pathway is emerging as an important regulator for a number of clinical conditions associated with the overproduction of inflammatory mediators. Here, we will focus on a possible role of BH4 in the onset or progression of depression, Parkinson and Alzheimer diseases.

The de novo BH4 pathway reduces guanosine triphosphate (GTP) into BH4 by the successive action of three enzymes: GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydrobiopterin (PTPS), and sepiapterin reductase (SPR).

Nov 7, 2018 · We find that genetic inactivation of GTP cyclohydrolase 1 (GCH1, the rate-limiting enzyme in the synthesis of BH4) and inhibition of sepiapterin reductase (the terminal enzyme in the synthetic...

BH4 de novo synthesis involves the sequential activation of three enzymes, the major controlling point being GTP cyclohydrolase I (GCH1). Complementary salvage and recycling pathways ensure that BH4 levels are tightly kept within a physiological range in the body.

BH4 is the essential cofactor for phenylalanine hydroxylase (PAH), tyrosine 3‐hydroxylase (TyrH), tryptophan‐5‐hydroxylase (TrpH), three isoforms of nitric oxide synthase (NOS), and glyceryl‐ether monooxygenase. 2, 3 De novo biosynthesis and pterin salvage pathways are involved in BH4 biosynthesis. GTP cyclohydrolase I (GTPCH), 6 ...

Feb 10, 2022 · Tyrosine-3-hydroxylase and tryptophan-5-hydroxylase are aromatic hydroxylase enzymes that use BH4 as a co-factor to convert the amino acids tyrosine and tryptophan to levodopa and 5-hydroxytryptophan.

Tetrahydrobiopterin (BH4) deficiencies are disorders affecting phenylalanine metabolism in liver and neurotransmitters biosynthesis in brain. BH4 is the essential cofactor in the enzymatic hydroxylation of 3 aromatic amino acids (phenylalanine, tyrosine, and tryptophan).

Jul 28, 2020 · This review aims at providing an update of the knowledge about metabolism and role of BH4 in brain function, from preclinical to clinical studies, addressing some therapeutic implications.

May 3, 2023 · The de novo BH4 pathway reduces guanosine triphosphate (GTP) into BH4 by the successive action of three enzymes: GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydrobiopterin (PTPS), and sepiapterin reductase (SPR).

Jul 29, 2020 · Tetrahydrobipterin (BH4) is a pivotal enzymatic cofactor required for the synthesis of serotonin, dopamine and nitric oxide. BH4 is essential for numerous physiological processes at periphery and central levels, such as vascularization, inflammation, glucose homeostasis, regulation of oxidative stress and neurotransmission.