Metabolite control of L-fucose utilization

Area of Science:

• Biochemistry
• Enzymology
• Metabolic Regulation

Background:

• Thyroid fucokinase plays a role in cellular metabolism.
• Understanding its regulatory mechanisms is crucial for comprehending thyroid function.
• Metabolite interactions with fucokinase are not fully elucidated.

Purpose of the Study:

• To investigate the regulatory effects of various metabolites, particularly nucleotide sugars, on thyroid fucokinase activity.
• To identify specific nucleotide sugars that modulate fucokinase function.
• To explore potential physiological roles of these interactions.

Main Methods:

• Enzyme activity assays were performed using thyroid fucokinase.
• A range of metabolites, including adenosine diphosphate (ADP), guanosine monophosphate (GMP), and various guanine nucleotide sugars, were tested.
• The effects of these compounds on fucokinase activity were quantified.

Main Results:

• Thyroid fucokinase demonstrated sensitivity to several metabolites.
• Adenosine diphosphate (ADP) inhibited the enzyme, while guanosine monophosphate (GMP) stimulated it.
• Guanine nucleotide sugars selectively modulated fucokinase activity.
• GDP-alpha-D-mannose, GDP-alpha-D-glucose, GDP-alpha-D-rhamnose, and GDP-alpha-L-fucose were found to be strongly inhibitory.
• GDP-alpha-D-mannose showed a stimulatory effect, though its physiological relevance requires further investigation.
• GDP-beta-L-fucose exhibited inhibitory effects, suggesting a potential feedback inhibition mechanism.

Conclusions:

• Thyroid fucokinase is subject to complex metabolic regulation.
• Guanine nucleotide sugars are key modulators of fucokinase activity.
• GDP-beta-L-fucose may function as an end-product inhibitor, providing a feedback control mechanism in metabolic pathways.