Threonine is the best substrate for D-lactate formation in octopus tentacle.
Carbon sources for D-lactate and enzyme activities related to D-lactate formation were investigated using cell-free homogenates of Octopus vulgaris tentacle tissue. The results are as follows: a) The best precursor for D-lactate formation was threonine and second best precursors were glycine and fructose-1,6-bisphosphate. Threonine and glycine served as precursors only in presence of glutathione. b) Both amino acids were precursors for methylglyoxal from which D-lactate was synthesized. Alanine, cysteine and serine were not precursors. We present a metabolic map for D-lactate formation in octopus in order to explain these experimental results.
Akagi
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Kurashiki Central Hospital, Pharmaceutical Center, Miwa, Kurashiki, Japan.
Ohmori
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D000818:Animals; D005121:Extremities / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism; D008297:Male; D049831:Octopodiformes / Q000378:metabolism*; D011765:Pyruvaldehyde / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013912:Threonine / Q000378:metabolism*; D013997:Time Factors
D013912:Threonine; D019344:Lactic Acid; D011765:Pyruvaldehyde; D005978:Glutathione; D005998:Glycine