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![Metabolism of tyrosine by the desert locust Schistocerca gregaria nervous tissue için kapak resmi Metabolism of tyrosine by the desert locust Schistocerca gregaria nervous tissue için kapak resmi](/client/assets/d79c3e4af2b6d196/ctx/images/no_image.png)
Metabolism of tyrosine by the desert locust Schistocerca gregaria nervous tissue
Başlık:
Metabolism of tyrosine by the desert locust Schistocerca gregaria nervous tissue
Yazar:
Mir, Anis Khusro, author.
ISBN:
9780438053502
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (141 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: P. F.T Vaughan.
Özet:
Initial studies were concerned with the development of an adequate method for the separation of tyrosine (TYR) and its metabolites. Separation of N-acetyloctopamine (NAOA), N-acetyldopamine (NADA), N-acetyltyramine (NATA), octopamine (OA), dopamine (DA), L-3, 4-dihydroxyphenylalanine (L-DOPA), tyramine (TA) and TYR was achieved by ion-pair chromatography using a Partisil-10 ODS column. This high performance liquid chromatographic method is an improvement on the thin layer chromatographic and column chromatographic procedures used previously. NATA, NADA and NAOA were the major products when either [3H]-L tyrosine or [3H]-tyramine were incubated with thoracic or cerebral ganglia of the desert locust Schistocerca gregaria. No label was incorporated into L-DOPA under these conditions even in the presence of electron donors, such as 6,7-dimethy1-5,6,7,8-tetrahydropteridine and ascorbic acid, although 2-3% of the radioactivity could be recovered in DA and OA. Addition of the aromatic amino acid decarboxylase inhibitor, 3-hydroxybenzylhydrazine (NSD 1015), prevented the formation of N-acetyl compounds from [3H]-L-tyrosine, without resulting in an accumulation of label in L-DOPA. In contrast, incubation of samples of haemolymph with [3H]-L-tyrosine resulted in the recovery of 7% of label in L-DOPA, which was increased to 17% in the presence of NSD 1015. These results provide evidence that the initial step in the synthesis of NADA and NAOA by S. gregaria nervous tissue is the decarboxylation of TYR to TA. The subsequent conversion of TA to NADA and NAOA suggests that TA, and not L-DOPA, is an intermediate in the synthesis of these compounds by S. gregaria nervous tissue. This study also provides evidence that NATA is the main intermediate on the pathway to NADA when thoracic ganglia are incubated with either [3H]-L-tyrosine or [3H]-tyramine. The o-hydroxylation of NATA represents the major route for the synthesis of NADA in vitro, with only about 10% of the radioactivity recovered in NADA coming from the N-acetylation of DA. o-Hydroxylation of NATA to NADA in S.gregaria nervous tissue requires an electron donor, such as ascorbic acid, and is inhibited by 5-fluorotryptamine. The enzyme catalyzing this reaction appears to resemble a mixed function oxidase and is unlikely to be an o-hydroxylase with properties similar to tyrosine hydroxylase or tyrosinase from mammals and insect haemolymph. Complications in the study of the metabolic pathways of monoamines in insect nervous tissue are discussed.
Notlar:
School code: 0547
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684463.1) | 684463-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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