Substrate specificities of rat liver peroxisomal acyl-CoA oxidases: palmitoyl-CoA oxidase (inducible acyl-CoA oxidase), pristanoyl-CoA oxidase (non-inducible acyl-CoA oxidase), and trihydroxycoprostanoyl-CoA oxidase.
نویسندگان
چکیده
Rat liver peroxisomes contain three acyl-CoA oxidases:palmitoyl-CoA oxidase, pristanoyl-CoA oxidase, and trihydroxycoprostanoyl-CoA oxidase. The three oxidases were separated by anion-exchange chromatography of a partially purified oxidase preparation, and the column eluate was analyzed for oxidase activity with different acyl-CoAs. Short chain mono (hexanoyl-) and dicarboxylyl (glutaryl-)-CoAs and prostaglandin E2-CoA were oxidized exclusively by palmitoyl-CoA oxidase. Long chain mono (palmitoyl-) and dicarboxylyl (hexadecanedioyl-)-CoAs were oxidized by palmitoyl-CoA oxidase and pristanoyl-CoA oxidase, the former enzyme catalyzing approximately 70% of the total eluate activity. The very long chain lignoceroyl-CoA was also oxidized by palmitoyl-CoA oxidase and pristanoyl-CoA oxidase, the latter enzyme catalyzing approximately 65% of the total eluate activity. Long chain 2-methyl branched acyl-CoAs (2-methylpalmitoyl-CoA and pristanoyl-CoA) were oxidized for approximately 90% by pristanoyl-CoA oxidase, the remaining activity being catalyzed by trihydroxycoprostanoyl-CoA oxidase. The short chain 2-methylhexanoyl-CoA was oxidized by trihydroxycoprostanoyl-CoA oxidase and pristanoyl-CoA oxidase (approximately 60 and 40%, respectively, of the total eluate activity). Trihydroxycoprostanoyl-CoA was oxidized exclusively by trihydroxycoprostanoyl-CoA oxidase. No oxidase activity was found with isovaleryl-CoA and isobutyryl-CoA. Substrate dependences of palmitoyl-CoA oxidase and pristanoyl-CoA oxidase were very similar when assayed with the same (common) substrate. Since the two oxidases were purified to a similar extent and with a similar yield, the contribution of each enzyme to substrate oxidation in the column eluate probably reflects its contribution in the intact liver.
منابع مشابه
Separate peroxisomal oxidases for fatty acyl-CoAs and trihydroxycoprostanoyl-CoA in human liver.
Fatty acyl-CoAs as well as the CoA esters of the bile acid intermediates di- and trihydroxycoprostanic acids are beta-oxidized in peroxisomes. The first reaction of peroxisomal beta-oxidation is catalyzed by acyl-CoA oxidase. We recently described the presence of two fatty acyl-CoA oxidases plus a trihydroxycoprostanoyl-CoA oxidase in rat liver peroxisomes (Schepers, L., P. P. Van Veldhoven, M....
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The composite trihydroxycoprostanoyl-CoA oxidase cDNA sequence, derived from overlapping clones isolated via screening of two different rat liver expression libraries, consisted of 2509 bases and contained an open reading frame of 2046 bases, encoding a protein of 681 amino acids with a calculated molecular mass of 76711 Da. The reading frame and identity of the trihydroxycoprostanoyl-CoA oxida...
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ورودعنوان ژورنال:
- The Journal of biological chemistry
دوره 267 28 شماره
صفحات -
تاریخ انتشار 1992