Finding of a homarine-synthesizing enzyme in turban shell and some properties of the enzyme.
A homarine-synthesizing enzyme was found for the first time in cell-free extract from turban shell (Batillus cornutus) and the enzyme was purified 36.2-fold and characterized. Properties of the enzyme were as follows: substrates were picolinic acid (pyridine-2-carboxylic acid) and S-adenosyl-L-methionine; optimum temperature for the enzymic reaction was 25 degrees C; optimum pH for the enzymic reaction was 6.3; and the Km values for picolinic acid and S-adenosyl-L-methionine were calculated at 317 and 14.5 microM, respectively. Among pyridine carboxylic acids, only picolinic acid was methylated with S-adenosyl-L-methionine by this enzyme. The molecular weight of the enzyme was estimated to be 70,800. The enzyme activity was inhibited by heavy metal ions, S-adenosyl-L-homocysteine, adenosine, homocysteine, and sinefungin. Homarine, which is an osmotic pressure regulator, morphogen, etc.; is enzymatically synthesized by the methylation of picolinic acid with S-adenosyl-L-methionine and the enzyme activity may be controlled by S-adenosyl-L-homocysteine (reaction product) and its related compounds.
Nishitani
H
H
R & D Center, Terumo Corporation, Kanagawa, Japan.
Kikuchi
S
S
Okumura
K
K
Taguchi
H
H
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000470:Alkaloids / Q000378:metabolism; D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D004791:Enzyme Inhibitors; D005998:Glycine / Q000031:analogs & derivatives / Q000378:metabolism; D007448:Invertebrates / Q000201:enzymology; D008780:Methyltransferases / Q000378:metabolism*; D010848:Picolinic Acids / Q000378:metabolism* / Q000494:pharmacology; D012435:S-Adenosylhomocysteine / Q000494:pharmacology; D012436:S-Adenosylmethionine / Q000378:metabolism; D012908:Snails / Q000201:enzymology*; D013045:Species Specificity
D000470:Alkaloids; D002413:Cations, Divalent; D004791:Enzyme Inhibitors; D010848:Picolinic Acids; C009560:trigonelline; C095922:N-succinylglycine; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D008780:Methyltransferases; C095923:picolinate methyltransferase; D000241:Adenosine; C010981:homarine; C030614:picolinic acid; D005998:Glycine; C006235:sinefungin