Purification and characterization of beta-cyanoalanine synthase and cysteine synthases from potato tubers: are beta-cyanoalanine synthase and mitochondrial cysteine synthase same enzyme?
beta-Cyanoalanine synthase (CAS; EC 4.4.1.9) and two kinds of cysteine synthases (CS; EC 4.2.99.8) have been purified from the particulate fraction of potato tubers. By DEAE Sephacel and Resource PHE chromatography, CAS activity was separated from two CS activities, designated as CS-1 and CS-2. The molecular masses of CAS, CS-1 and CS-2 were estimated to be 37, 39 and 34 kDa, respectively, by SDS-PAGE analysis. The purified CAS had CS activity, and both CS-1 and CS-2 had CAS activity. However, CAS and CSs had significant differences in kinetic characters. The antibody raised against purified CAS discriminated CAS from CSs, whereas the antibody raised against purified CS-2 recognized CS-1 and CS-2 but not CAS. The molecular mass and the partial amino acid sequence of CS-2 were similar to those of the cytosolic CS of potato, whereas the molecular mass of CS-1 was similar to that of the plastidic CS. The partial amino acid sequence of CAS was similar to those of CS isozymes, especially the mitochondrial CS isolated from spinach.
Maruyama
A
A
Biological Institute, Graduate School of Science, Tohoku University, Sendai, Japan.
Ishizawa
K
K
Takagi
T
T
D000595:Amino Acid Sequence; D000818:Animals; D003547:Cysteine Synthase / Q000302:isolation & purification / Q000378:metabolism*; D008190:Lyases / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000201:enzymology*
D003547:Cysteine Synthase; D008190:Lyases; C019955:beta-cyanoalanine synthase