Transaminase from Lactic Acid Bacteria, Streptococcus faecalis R. ATCC 8043, Grown on Vitamin B6-Deficient Medium
1984 Volume 37 Issue 4 Pages 333-341
Details
1984 Volume 37 Issue 4 Pages 333-341
Biological effect of vitamin B6-deficiency on biosynthesis of B6-enzymes in Streptococcus faecalis R. ATCC 8043 was investigated.
Vitamin B6-enriched cells were grown on the medium added with 10μg per ml of pyridoxal, and B6-deficient cells were grown on synthetic amino acid medium free from vitamim B6-vitamers which was supplemented with 200μg per ml of one of the stereoisomers of alanime (D-, DL-, or L-alanine).
The transaminase activity of B6-enriched cells was compared with that of B6-deficiemt cells of sonicated cell-free extracts. Transaminase of B6-enriched cells was made up of a half part of apoenzyme and another half part of holoenzyme, while the enzyme of B6-deficient cells consists of a quarter part or one third part of holoenzyme of total activity.
Purifed preparations of transaminase obtained from those of B6-enriched or B6-deficient cells of Streptococcus faecalis R. were confirmed as a single protein preparation by acrylamide disc gel electrophoresis.
Molecular weight of transaminase from B6-enriched cells was calculated to be about 32, 000, while the molecular weight of the enzyme purified from B6-deficient cells was calculated to be about 64, 000 by gel filtration of sephadex G-150 column.
Michaelis constant (Km) of both enzymes for pyridoxal 5'-phosphate was calculated to be 5.6×10-7M. Km values for α-ketoglutarate and aspartate were calculated to be 3.0-6.5×10-4M and 2.2-5.7×10-3M, respectively.
