Lack of tryptophan-niacin relationship in corn and tobacco.
نویسندگان
چکیده
Although the biosynthesis of niacin in Neurospora and mammals has been elucidated in a general way, the pathway by which this vitamin is formed in plants has remained obscure. An increase in the niacin content of cereals during germination has been observed (1). Winterstein and Trier (2) suggested that niacin is derived from proline, whereas Guggenheim (3) proposed ornithine as a precursor. Following the observation of Krehl et al. (4) that tryptophan could replace niacin in the diet of the rat, evidence of a tryptophan-niacin relationship in plants has been sought (5-13). Several of these efforts have led to suggestive evidence that tryptophan or various of its metabolites are precursors of niacin. In general, the evidence has been based on observed small increases in the niacin content of plants grown in the presence of suspected precursors. Recently, isotopic evidence has conclusively excluded the niacin-precursor role of tryptophan in some plants and bacteria (14). The failure of ring-labeled tryptophan to serve as a precursor of nicotine formed by root cultures of tobacco (15) coupled with the evidence that the pyridine ring of nicotine arises directly from nicotinic acid (16) constitutedstrong evidence against the conversion of tryptophan to niacin in this plant. Leete (17) and Grimshaw and Marion (18) have confirmed the failure of tryptophan and its metabolites to serve as a precursor of nicotine using intact Nicotiana glauca.
منابع مشابه
Lack of a Tryptophan-Niacin Relationship in Corn and Tobacco*
Although the biosynthesis of niacin in Neurospora and mammals has been elucidated in a general way, the pathway by which this vitamin is formed in plants has remained obscure. An increase in the niacin content of cereals during germination has been observed (1). Winterstein and Trier (2) suggested that niacin is derived from proline, whereas Guggenheim (3) proposed ornithine as a precursor. Fol...
متن کاملA quantitative study of the relationship between tryptophan and niacin in Neurospora.
Numerous studies elucidating the probable pathway of tryptophan synthesis (1,2) and of niacin synthesis (3-9) in Neurospora have been reported. That tryptophan may serve as a precursor of niacin was first suggested by the results of nutritional studies with mammals (10, 11). This relationship has been confirmed for the rat by tracer experiments (12). A tryptophan-niacin relationship has also be...
متن کاملAmino acid imbalance as related to tryptophan requirement of the rat.
In 1945, Krehl et al. (2) noted that the growth of rats was depressed by decreasing the casein content of a basal diet from 15 to 9 per cent through addition of 40 per cent of corn. The depression in growth could be corrected by addition of either niacin or tryptophan to the diet. Since this observation, numerous investigators have been concerned with factors that were considered to be related ...
متن کاملThe absence of a tryptophan-niacin relationship in Escherichia coli and Bacillus subtilis.
Nutritional studies with mammals led to the first suggestion of a relationship between tryptophan and niacin (Krehl et al., 1945). Subsequent investigations have established tryptophan as a precursor of niacin in many organisms and have led to the identification of several of the intermediates in this biosynthetic pathway (for reviews, see Dalgliesh, 1951; Bonner and Yanofsky, 1951). Direct dem...
متن کاملThe metabolic interrelationship between tryptophan, pyridoxine, and nicotinic acid; forced feeding studies in rats.
The addition of corn products to a synthetic low protein diet very low in nicotinic acid has been reported by Krehl and coworkers (1,2) to depress growth in rats. This growth retardation could be prevented by tryptophan as well as by nicotinic acid. These findings have been confirmed in this laboratory by the paired feeding technique (3) and by other investigators (4, 5). The interchangeability...
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ورودعنوان ژورنال:
- The Journal of biological chemistry
دوره 234 1 شماره
صفحات -
تاریخ انتشار 1959