Phenylalanine residues dehydrogenases

Fhenobarbital, cytochrome P-450 reductase and, ISO Phenols, catalase and, 398 Phenylalanine residues, glyceraldehyde-3-phosphate dehydrogenase, 11, 33 Phenyl mercuric acetate, glutathione reductase and, 141... 

Figure 6a shows the modeled oc helix F interface in human 17 3-hydroxysteroid dehydrogenase type 1 in which phenylalanine-160 and alanine-161 form an anchor. Both residues have important stabilizing interactions across the dimer interface. Alanine-161 is 4.1 A from alanine-161 on the other subunit. Alanine-161 has a hydrophobic interaction with alanine-157, which is in the segment between the conserved tyrosine-155 and lysine-159. There is a hydrophobic... 

Figure 6b shows the modeled a helix F interface in human 17P-hydroxysteroid dehydrogenase type 2. Alanine-237 is 3 A from the hydrophobic part of the side chain of methionine-241 on the other subunit. Methionine-241 is 3.2 A from serine-234. Alanine-230 is 3.7 A from phenylalanine-242 and 4.5 A from valine-245. Alanine-238, the other anchoring residue, is 4.1 A from alanine-238 on the other subunit. 

Dehydrogenases exhibit a fluorescence similar to that of tryptophan. Irradiation of dehydrogenases at 280 nm gives an emission maximum at 340 nm (Figs. 2 and 3). This pattern is characteristic of enzymes which contain tryptophan and can be designated protein fluorescence. The other side residues, tyrosine or phenylalanine, fluoresce very weakly and probably do not contribute significantly to the fluorescence of the enzyme7). 

There are several points of attack on the protein molecule, and in glutamate dehydrogenase and RNase, exposure to UV in the presence of psoralen extensively modified histidine, methionine, tryptophan, phenylalanine and tyrosine residues by photo-oxidation. ... 

---