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Biomedical subjects

A I Scott

Publications and source records attributed to A I Scott.

At least 145 records · Page 8Linked to original sources
PubMed1981

Applications of 13C NMR to metabolic studies.

It is our view that the above examples, most of which have been published in the last two years, represent the beginnings of a new field and that in spite of major problems in instrumentation and programming, the essential feasibility of using enriched 13C substrates for metabolic processes as a noninvasive technique has been firmly established. With the caveat that a rigorous protocol for signal assignment must be devised, we can look forward to many applications of this method in a wide range of biological systems.

Animals↗
PubMed1979

Purification and properties of strictosidine synthetase (an enzyme condensing tryptamine and secologanin) from Catharanthus roseus cultured cells.

Strictosidine synthetase, which catalyzes the condensation of tryptamine with secologanin to form strictosidine (isovincoside), was purified 740-fold to homogeneity from cultured cells of Catharanthus roseus in 10% yield. The specific activity is 5.85 nkat/mg. The molecular weight as estimated by gel filtration is 38,000. The isoelectric point is 4.6. Apparent Km values for tryptamine and secologanin are 0.83 and 0.46 mM, respectively. The enzyme shows a broad pH optimum between 5.0 and 7.5. The product of the enzymic reaction is exclusively strictosidine, while no trace of its epimer vincoside can be detected. Sulfhydryl inhibitors have no effect on the enzyme. End products in the biosynthetic pathway of indole alkaloids such as ajmalicine, vindoline, and catharanthine do not inhibit the activity of strictosidine synthetase.

Carbon-Nitrogen Lyases↗
PubMed1976

The biosynthesis of vitamin B12.

The use of 13C-Fourier transform nuclear magnetic resonance (F.t.-n.m.r.) has led to the observation that while 8 molecules of [2-13C]ALA are incorporated into vitamin B12 in P. shermanii, [5-13C]ALA labels only seven of the carbon atoms of cyanocobalamin, i.e. one of the amino methyl groups of ALA is "lost" in the process. It has also been confirmed that seven of the methyl groups of B12 are derived from 13CH3-enriched methionine and further that the chirality of the gemdimethyl grouping at C12 labelled with [13CH3]methionine is R. A soluble enzyme mixture from the 37000 or 100000 g supernatant of disrupted cells of P. shermanii converts both 14 C-labelled ALA and [14C]uro'gen III to cobyrinic acid, the simplest corrinoid material on the pathway to vitamin B12 and the coenzyme, in presence of NADPH, Co2+, Mg2+, S-adenosyl-methionine and glutathione. Multiply-labelled uro'gens (13C, 14C and 3H) have been used to show that incorporation takes place without randomization. A sequence for corrin synthesis from uro'gen III is presented.

Aminolevulinic Acid↗