Studies on the transacylation of retinol catalyzed by acyl coenzyme A:retinol O-acyltransferase
dc.contributor.advisor | James Allen Olson | |
dc.contributor.author | Ball, Mark | |
dc.contributor.department | Biochemistry, Biophysics and Molecular Biology | |
dc.date | 2018-08-16T18:37:18.000 | |
dc.date.accessioned | 2020-07-02T06:08:03Z | |
dc.date.available | 2020-07-02T06:08:03Z | |
dc.date.copyright | Thu Jan 01 00:00:00 UTC 1987 | |
dc.date.issued | 1987 | |
dc.description.abstract | <p>Acyl coenzyme A:retinol O-acyltransferase (ARAT), a microsomal enzyme, is thought to catalyze the transacylation reaction whereby retinol is esterified in vivo. Therefore, by means of an in-vitro assay method measuring net synthesis of retinyl esters, properties of the enzyme in various tissues were studied;ARAT was characterized in the liver of a polar bear, a species with exceptionally large vitamin-A reserves. The activity observed was unusually high. Vitamin A was present in the liver at 8050 [mu]g/g tissue, with 98% of the vitamin in its ester form. However, the activity of ARAT in rat mammary tumor, a tissue in which retinyl esters do not accumulate, was very low. Furthermore, administration of vitamin A to the animals enhanced ARAT activity in both tumor and liver. Thus, ARAT may have a physiological role in the esterification of retinol in vivo;ARAT was inhibited in vitro by various retinoids, including 13-cis-retinoic acid, a drug used at high doses in the treatment of recalcitrant acne. However, the drug not only inhibited benzo(a)pyrene hydroxylation also, but it increased the permeability of the microsomes to mannose-6-phosphate, as evidenced by a rise in mannose-6-phosphatase activity. Therefore, retinoids that inhibit ARAT in vitro should also be tested on other membrane-bound enzyme systems. Inasmuch as four other amphiphiles were much less effective at increasing membrane permeability to mannose-6-phosphate in vitro, 13-cis-retinoic acid may act in vivo, at least in part, by disrupting membranes;CoA thioesters of oleic and C[subscript]12-C[subscript]20 saturated fatty acids were effective substrates for rat-liver ARAT in vitro, whereas polyunsaturated derivatives were virtually ineffective. ARAT from polar-bear liver displayed a similar specificity. However, ARAT specificity observed in vitro fails to account for the fatty-acid composition of retinyl esters in vivo, inasmuch as retinol exists in the liver mainly as the palmitate ester, with lesser amounts of retinyl stearate and oleate. Thus, a second retinol-acylating enzyme may exist in the liver, working in conjunction with ARAT.</p> | |
dc.format.mimetype | application/pdf | |
dc.identifier | archive/lib.dr.iastate.edu/rtd/8615/ | |
dc.identifier.articleid | 9614 | |
dc.identifier.contextkey | 6342951 | |
dc.identifier.doi | https://doi.org/10.31274/rtd-180813-13124 | |
dc.identifier.s3bucket | isulib-bepress-aws-west | |
dc.identifier.submissionpath | rtd/8615 | |
dc.identifier.uri | https://dr.lib.iastate.edu/handle/20.500.12876/81623 | |
dc.language.iso | en | |
dc.source.bitstream | archive/lib.dr.iastate.edu/rtd/8615/r_8805045.pdf|||Sat Jan 15 02:14:30 UTC 2022 | |
dc.subject.disciplines | Biochemistry | |
dc.subject.keywords | Biochemistry and biophysics | |
dc.subject.keywords | Biochemistry | |
dc.title | Studies on the transacylation of retinol catalyzed by acyl coenzyme A:retinol O-acyltransferase | |
dc.type | article | |
dc.type.genre | dissertation | |
dspace.entity.type | Publication | |
relation.isOrgUnitOfPublication | faf0a6cb-16ca-421c-8f48-9fbbd7bc3747 | |
thesis.degree.level | dissertation | |
thesis.degree.name | Doctor of Philosophy |
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