title: ATP-NGF-complex, but not NGF, is the neuroprotective ligand.
abstract: We have shown previously that nerve growth factor (NGF) requires only low nanomolar ATP concentrations in the cell culture medium to protect cortical rat neurons (CRN) from cellular damage induced by staurosporine (STS). We have also demonstrated before that NGF and other growth factors form stable non-covalent complexes with ATP. Here we demonstrated that 8N(1)ATP-NGF, but not NGF, protected CRN against damage. The photo-reactive ATP derivative 8N(3)ATP was incubated with NGF and was trapped in its position by UV irradiation forming a covalent bond. The cross-link with a molar ratio of 1:1 (8N(1)ATP:NGF) was confirmed by mass spectrometry. Circular dichroism experiments revealed that 8N(1)ATP altered the secondary structure of NGF in the same way as ATP did. Covalently bound 8N(1)ATP-NGF was shown to be stable in the presence of the ATP-hydrolyzing enzyme alkaline phosphatase while the non-covalent ATP-NGF-complex dissociated with the removal of free ATP from the solution. 8N(1)ATP-NGF protected CRN against damage by STS independently of free ATP in the culture medium. These results suggest that the ATP-NGF-complex, but not NGF, is the active ligand.
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie, Fachbereich Chemie und Pharmazie, Germany.
authors.forename: Katja Bettina
authors.initials: KB
authors.lastname: Ferenz
authors.forename: Karsten
authors.initials: K
authors.lastname: Rose
authors.forename: Simone
authors.initials: S
authors.lastname: König
authors.forename: Josef
authors.initials: J
authors.lastname: Krieglstein
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002942:Circular Dichroism; D008024:Ligands; D013058:Mass Spectrometry; D020932:Nerve Growth Factor / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008024:Ligands; D018696:Neuroprotective Agents; D000255:Adenosine Triphosphate; D020932:Nerve Growth Factor