Raman spectrum of protocatechuate dioxygenase from Pseudomonas putida new low frequency bands

Abstract

The Raman spectrum (441.6 nm excitation) of protocatechuate 3,4-dioxygenase (PCD) from Pseudomonas putida shows resonance enhanced bands at 1605, 1504, 1270, 858, and 830 cm-1 which are due to the p-hydroxyphenyl group of tyrosine coordinated to iron. In addition, we observe strong resonance enhanced bands at 592 and 524 cm-1 and weak (presumably iron-ligand) vibrations at 465, 423, and 371 cm-1. Recent publications of the Raman spectrum of PCD from Pseudomonas aeruginosa (Tatsuno , J. Am. Chem. Soc. 100, 4614-4615 (1978) and Keyes , Biochem. Biophys. Res. Comm. 83, 941-945 (1978) using 488 and 514 nm excitation did not report these bands. Our 441.6 nm excitation Raman spectrum of human serum transferrin, another metalloprotein with an iron-tyrosine linkage, does not show the 592 and 524 cm-1 bands and has only two very weak bands at about 423 and 364 cm-1. We discuss several interpretations of these data.