Naslov
Crystal Structure of Citrobacter freundii Asp214Ala Tyrosine Phenol-lyase Reveals that Asp214 is Critical for Maintaining a Strain in the Internal Aldimine

Autori
Milić, Dalibor ; Demidkina, Tatyana V. ; Zakomirdina, Lyudmila N. ; Matković-Čalogović, Dubravka ; Antson, Alfred A.

Izvornik
Croatica chemica acta (0011-1643) 85 (2012), 3; 283-288

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
tyrosine phenol-lyase; chemical strain; internal aldimine; pyridoxal 5′-phosphate; X-ray structure

Sažetak
Tyrosine phenol-lyase (TPL) is a pyridoxal-5′-phosphate (PLP) dependent enzyme which catalyzes β-elimination of L-tyrosine. In the holoenzyme the protonated pyridinium N1 atom of the PLP cofactor is hydrogen-bonded to the side chain of Asp214. Here we report the X-ray structure of C. freundii D214A TPL determined at 1.9 Å resolution. Comparison with the structure of the wild-type TPL shows that the D214A replacement induced significant conformational reorganization in the active site leading to its partial closure. Significantly, in D214A TPL the strain in the internal aldimine is completely released and the pyridine N1 atom of PLP is deprotonated. These observations explain the considerably reduced activity of the D214A TPL towards its substrates [T. V. Demidkina et al., Biochim. Biophys. Acta, Proteins Proteomics 1764 (2006) 1268–1276]. The reported structure reveals that Asp214 is critical for maintaining the strain in the internal aldimine. We argue that this strain is used by the enzyme to accelerate the transaldimination reaction, the first step in the enzymatic catalysis.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA