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Abstract
Thirty-two yeast species belonging to twelve genera were examined for the occurrence of inhibition of ornithine carbamoyltransferase by arginase (epiarginasic regulation) and related properties. Obligate aerobes were devoid of this regulation. Among fermenting species, Schizosaccharomyces and budding genera had different properties: all Schizosaccharomyces species were devoid of this regulation whereas all species of budding yeasts showing a weak or absent Pasteur effect had this regulation. Strains showing a strong Pasteur effect and taxonomically related to Saccharomyces (Kluyveromyces had the regulation, whereas species classified in genera that include species which are obligate aerobes did not.
We confirm that the absence of epiarginasic regulation is correlated with a mitochondrial localization of ornithine carbamoyltransferase but not with the function of the mitochondria in Schizosaccharomyces japonicus. In this case, compartmentation could serve to channel anabolic and catabolic functions. Although, in general, the arginase of negative epiarginasic species had no affinity for cytosolic ornithine carbamoyltransferase, one exception was found (Hansenula anomala).
Regulation by repression of ornithine carbamoyltransferase and induction of arginase by arginine was the general rule. These types of regulation of enzyme synthesis were only absent in yeasts in which compartmentation is present and could serve as the basis for anabolismcatabolism exclusion.
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