Effects of protein phosphorylation with p43v-abl and protein kinase A catalytic subunit on fluorescence intensity

To study the effect of phosphorylation on protein conformation, a fluorescence spectroscopic study was performed on phosphorylated enolase and histoneH1 proteins. The peak of fluorescence was 330 and 360 nm for each protein, respectively, when excited at 287 nm. The intensities of the fluorescence were measured during the phosphorylation reactions with the protein kinase A and p43v-abl, for serine, threonine and tyrosine, respectively. Slightly increased intensities at 330 and 360 nm for enolase and histoneH1 protein were observed by phosphorylation with p43v-abl, whereas decreased intensities occurred with the protein kinase A catalytic subunit. These data suggest that micro-structural changes are induced at the residue, either tyrosine, serine or threonine in the protein.