Egg white injury

Biotin was originally discovered as part of the complex called bios, which promoted the growth of yeast, and separately, as vitamin H, the protective or curative factor in egg white injury - the disease caused by diets containing large amounts of uncooked egg white. The glycoprotein avidin in egg white binds biotin with high affinity. This has been exploited to provide a variety of extremely sensitive assay systems. 

The original interest in avidin was because of the egg white injury that was subsequently shown to be avidin-induced biotin deficiency. Thereafter, avidin was used because of its high affinity for biotin (a dissociation constant of 10 mol per L), not only to induce experimental biotin deficiency, but also to bind to biotin in isolated enzymes and thus, by irreversible inhibition, demonstrate the coenzyme role of biotin. Because of the stability of the avidin-biotin complex, it has not been possible to use immobilized avidin as a means of purifying biotin enzymes - there seems to be no way in which the enzyme can be released from avidin binding. Because of its high affinity for biotin, avidin is used to provide an extremely sensitive system for linking reporter molecules in a variety of analytical systems. 

Biorphen orphenadrine. biotin [inn, usan] (vitamin H coenzyme R Vitamin B7 Factor S) is a VITAMIN that occurs in yeast, eggs and liver, and is also produced by various other microorganisms and isolated from various higher plant sources, e.g. maize seedlings. A bacterial growth factor for egg white injury , it is an essential coenzyme in fat metabolism and other carboxylation reactions. Deficiency is rare apart from in certain paediatric disorders. It is incorporated into numerous multivitamin preparations. 

A few years later egg-white injury in chicks was shown to be associated with a deficiency of biotin in the tissues, despite its abundance in the diet [145]. In the same year, avidin was isolated from egg-white and its ability to inactivate biotin in vitro was demonstrated [146]. Gyorgy and Rose [235] fed rats with avidin but only found very small amounts of biotin in the faeces until the faeces were steamed. Biotin was then released from the avidin-biotin complex. As the result of further experiments, it was concluded that the fundamental cause of egg-white injury is the unavailability of biotin due to its fixation to avidin, so that biotin is not absorbed from the intestinal tract and is excreted in the faeces [237]. A similar conclusion was reached by Sullivan and Nicholls [603] who showed that when egg-white is cooked, avidin is denatured and rendered incapable of binding biotin. Egg-white injury has been produced experimentally in man and can be cured by the administration of biotin [607]. In a recent study, Peters [497] reported that raw egg-white has a direct toxic effect which is not associated with its action in causing biotin deficiency. It would appear, therefore, that further studies on egg-white injury must be more closely associated with a critical analysis of the different components of egg-white. 

Egg-white contains many different proteins and protein sub-fractions, each of which may act in one or more distinct ways both in vivo and in vitro. Thus although only the ovomucoid fraction elicits an anaphylactoid response in the rat, man of the protein components of egg-white are anaphylactic antigens. Moreover, although avidin causes biotin deficiency recent work suggests that egg-white injury may be attributable to an as yet unidentified fraction of egg-white. 

P. Gyorgy and C. S.Rose, Cure of Egg-White Injury in Rats by the Toxic Fraction (Avidin) of Egg White Given P ar enter ally, Science, N.Y. 94, 261-262 (1941). 

M. Sullivan and T. Nichols, Biotin and Egg-white Injury, Bull. Johns Hopkins Hosp. 69, 579-580 (1941). 

Diets containing a large percentage of egg white have a toxic effect on ani-malsi. The curative effect of a number of foodstuffs such as yeast, egg yolk, or milk on this egg-white injury was ascribed by Boas to the protective factor X . This factor was called vitamin H by Gyorgy who found that liver was relatively rich in this vitamin. Attempts at isolation led to concentrates obtained from liver and also from yeasts, which were highly active against egg-white injury in experimental animals. ... 

A number of compounds closely related to biotin can replace this vitamin as a growth factor for micro-organisms some can also cure egg white injury in animals. Other related compounds compete with the utilization of biotin by micro-organisms and thereby inhibit their growth. A few of the more important of these compounds are discussed below. 

Biotin, the anti-egg white injury factor, is presumably needed in human nutrition, but requirement would be difficult to establish. The intestinal bacteria synthesize this factor, and the average diet appears to supply... 

II, factor X, coenzyme R, anti-egg white injury, vitamin Bg, or vitamin H, was established in 1942 and its synthesis was achieved a year later (1). The absolute configuration of biotin was elucidated by x-ray crystallographic analysis on biotin and on a TVi-carboxy derivative (reviewed in 2). NMR studies (3,4) demonstrated that the conformation of the thiophene ring is the same in the solid state and in solution the sulfur atom lies above the thiophene ring and the valeric chain adopts a quasi-equatorial position (Fig. 1). The same conformation is encountered in the biotin sulfoxides (Fig. 2) (3,4). Numerous total syntheses of biotin have been published and this topic has been thoroughly reviewed recently (5), but the bulk of biotin is still produced according to the original Hoffmann-La Roche process (5). 

Looking back, it is now known that the deficiency (once called egg-white injury) occurs when the biotin in food combines with a factor in the protein of uncooked egg white (called avidin, because of its avidity for biotin) and that when egg white is cooked, avidin is inactivated. This also explains why, in early studies, liver and yeeist offered protection against egg-white injury. (Both of them contain sufficiently large amounts of biotin to saturate the avidin completely and leave a surplus of biotin available to meet the needs of experimental animals.)... 

A disorder which results from the binding of the vitamin biotin by a substance called avidin which is present in raw egg white. Egg white injury is characterized by shedding of flakes of skin, lack of appetite, loss of weight, and pains in the muscles. However, this disorder is rare in humans because (1) they do not normally eat sufficient amounts of raw egg white to bring about this condition and (2) most people cook eggs before eating them. 

H Biotin VI-5 In carboxylations (enzyme bound) Very rare ( egg white injury, dermatitis) [0.25 mg]... 

The third line involving biotin was the study of animal nutrition, first with rats, later extended to other animals. Here characteristic symptmns of egg-white injury were observed by Boas (27) in rats fed a diet contain-ing egg-white as the source of protein. It was found that the animals could... 

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