Transamination by human enzymes of some lactate dehydrogenase substrates
Başlık:
Transamination by human enzymes of some lactate dehydrogenase substrates
Yazar:
Percy, Rosalynd A., author.
ISBN:
9780438059092
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (210 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: H. G. Morgan.
Özet:
The mechanism, scope and specificity and clinical significance of the transamination reaction are reviewed. The role of transamination in metabolism is also summarised. Initially a transamination reaction between serine and ?-oxoglutarate catalyzed by human heart and liver extracts was demonstrated. Thin layer chromatography of the 2:4 dinitrophenylhydrazones of the oxo-acids in the assay mixture following a reaction confirmed this. Conditions for assay of serine transaminase in both tissues were established and the Michaelis constants for serine and alpha-oxoglutarate determined. The effect of reaction temperature on the transamination of serine with alpha-oxoglutarate was investigated and the results compared with corresponding effects on aspartate transaminase and alanine transaminase determinations, A comparison of the thermostabilities of the three transaminases was also undertaken. From these temperature studies, serine transaminase was shown to be similar to aspartate transaminase, while alanine transaminase was markedly different. This suggested that if serine transaminase was not a specific enzyme, then the transamination reaction between serine and alpha-oxoglutarate was more likely to be catalyzed by aspartate transaminase than by alanine transaminase. A similar conclusion was reached from comparative studies in which a better correlation between aspartate transaminase and serine transaminase was determined, in four different tissues, than between alanine transaminase and serine transaminase. Purchase of a Lot of serine from Calbiochem Ltd. which failed to support the transamination reaction, cast doubt on whether this reaction actually did occur. Studies with EDTA to show the presence of a metal ion inhibitor in the 'non-working' serine, or an activator in the 'working' serine proved negative. Am.ino acid analysis, thin layer chromatography and recrystallisation of the 'non-working' serine failed to detect the presence of any impurities in this chemical. Recrystallisation of the 'working' serine from acetone, however, resulted in a significant decrease in the transaminase activity measured. Evaporation of the mother liquors to dryness and application of the resulting compound to amino acid analysis revealed the presence of aspartic acid. The serine transaminase activities measured, therefore, can be attributed to aspartate transaminase. A possible transamination reaction between glycine and alpha-oxoglutarate, catalyzed by human heart and liver extracts was investigated, but no activity could be detected. Alpha-amino-n-butyrate was initially found to undergo transamination with alpha-oxoglutarate in the presence of human heart and liver extracts. The assay conditions and Michael is constants for a-amino-n-butyrate for both tissues were determined. The high Michaelis constant values suggested the possible presence of an alternative substrate in the alpha-amlno-n-butyrate, and which may be involved in a transamination reaction with alpha-oxoglutarate. Amino acid analysis revealed the presence of alanine as an impurity in the alpha-amino-n-butyrate. Thus the activities measured can, most probably, be attributed to alanine transaminase.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684686.1) | 684686-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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