GLYCINE-ENHANCED INHIBITION OF RAT-LIVER NUCLEOTIDE PYROPHOSPHATASE PHOSPHODIESTERASE-I BY EDTA - A FULL ACCOUNT OF THE REPORTED INHIBITIONBY COMMERCIAL PREPARATIONS OF ACIDIC FIBROBLAST GROWTH-FACTOR (FGF-1)/

The earlier reported inhibition of rat liver nucleotide pyrophosphatas e/phosphodiesterase I (EC 3.,1.,6.9/EC 3.1.4.1; NPP/PDE) by culture-gr ade acidic fibroblast growth factor (FGF-1) correlates with a low-M-r, contaminant, H-1-NMR analyses revealed EDTA in the total-volume fract ions of a gelfiltration experiment, where all the inhibitory activity of the FGF-1 preparation was recovered. NPP/PDE inhibition by EDTA (an d by unfractionated FGF-1 or the EDTA-containing fractions) was time-d ependent, blocked by the substrate p-nitrophenyl-dTMP, and strongly en hanced by glycine. The use of glycine buffers in earlier work was crit ical to the apparent inhibition by FGF-1, The results point to a confo rmational change favored by glycine that may be relevant to the biolog ical role of NPP/PDE. (C) 1998 Federation of European Biochemical Soci eties.