Correlation between catalytic activity and monomer-dimer equilibrium of bacterial alanine racemases.
From the reaction mechanism and crystal structure analysis, a bacterial alanine racemase is believed to work as a homodimer with a substrate, l-alanine or d-alanine. We analysed oligomerization states of seven alanine racemases, biosynthetic and catabolic, from Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, P. putida and P. fluorescens, with three different methods, gel filtration chromatography, native PAGE and analytical ultracentrifugation. All alanine racemases were proved to be in a dynamic equilibrium between monomeric and dimeric form with every methods used in this study. In both biosynthetic and catabolic alanine racemases, association constants for dimerization were high for the enzymes with high V(max) values. The enzymes with low V(max) values gave the low association constants. We proposed that alanine racemases are classified into two types; the enzymes with low and high-equilibrium association constants for dimerization.
Ju
Jiansong
J
College of Life Sciences, Hebei Normal University, Shijiazhuang 050016, Japan.
Xu
Shujing
S
Furukawa
Yukio
Y
Zhang
Yong
Y
Misono
Haruo
H
Minamino
Tohru
T
Namba
Keiichi
K
Zhao
Baohua
B
Ohnishi
Kouhei
K
D000411:Alanine Racemase / Q000737:chemistry* / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000737:chemistry*; D002850:Chromatography, Gel; D057075:Enzyme Assays; D010802:Phylogeny; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry* / Q000302:isolation & purification
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D000411:Alanine Racemase