Occurrence of D-Amino Acids and a pyridoxal 5'-phosphate-dependent aspartate racemase in the acidothermophilic archaeon, Thermoplasma acidophilum.
Free D-amino acid content in some archaea was investigated and D-forms of several amino acids were found in them. In the acidothermophilic archaeon, Thermoplasma acidophilum, the proportion of D-aspartate (D-Asp) to total Asp was as high as 39.7%. Crude extracts of Thermoplasma acidophilum had Asp-specific racemase activity that was pyridoxal 5'-phosphate (PLP)-dependent. The relative insensitivity to a SH-modifying reagent distinguished this activity from those of the PLP-independent Asp racemases found in other hyperthermophilic archaea (Matsumoto, M., et al., J. Bacteriol. 181, 6560-6563 1999). Thus, high levels of d-Asp should be produced by a new type(s) of Asp-specific racemase in Thermoplasma acidophilum, although the function of d-Asp in this archaeon remains unknown.
Long
Z
Z
School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo 108-8641, Japan.
Lee
J A
JA
Okamoto
T
T
Sekine
M
M
Nimura
N
N
Imai
K
K
Yohda
M
M
Maruyama
T
T
Sumi
M
M
Kamo
N
N
Yamagishi
A
A
Oshima
T
T
Homma
H
H
D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D000591:Amino Acid Isomerases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D018698:Glutamic Acid / Q000737:chemistry / Q000378:metabolism; D007930:Leucine / Q000737:chemistry / Q000378:metabolism; D008239:Lysine / Q000737:chemistry / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000502:physiology; D013237:Stereoisomerism; D013822:Thermoplasma / Q000201:enzymology / Q000378:metabolism*
D000596:Amino Acids; D004791:Enzyme Inhibitors; D001224:Aspartic Acid; D018698:Glutamic Acid; D010649:Phenylalanine; D011732:Pyridoxal Phosphate; D000591:Amino Acid Isomerases; C019749:aspartate racemase; D007930:Leucine; D008239:Lysine; D005033:Ethylmaleimide; D000409:Alanine