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B6db references: 15308337

type Journal Article
authors Saavedra CP, Encinas MV, Araya MA, Perez JM, Tantalean JC, Fuentes DE, Calderon IL, Pichuantes SE, Vasquez CC.
title Biochemical characterization of a thermostable cysteine synthase from Geobacillus stearothermophilus V
journal Biochimie
sel selected
ui 15308337
year (2004)
volume 86
number 17
pages 481-5
abstract The cysK gene encoding a cysteine synthase of Geobacillus stearothermophilus V was overexpressed in E. coli and the recombinant protein was purified and characterized. The enzyme is a thermostable homodimer (32 kDa/monomer) belonging to the beta family of pyridoxal phosphate (PLP)-dependent enzymes. UV-visible spectra showed absorption bands at 279 and 410 nm. The band at 279 nm is due to tyrosine residues as the enzyme lacks tryptophan. The 410 nm band represents absorption of the coenzyme bound as a Schiff base to a lysine residue of the protein. Fluorescence characteristics of CysK's Schiff base were influenced by temperature changes suggesting different local structures at the cofactor binding site. The emission of the Schiff base allowed the determination of binding constants for products at both 20 degrees C and 50 degrees C. At 50 degrees C and in the absence of sulphide the enzyme catalyzes the decomposition of O-acetyl-l-serine to pyruvate and ammonia. At 20 degrees C, however, a stable alpha-aminoacrylate intermediate is formed.
last changed 2009/02/02 10:47

B6db references