Thiamin status of a Melanesian population

Duffy, Peter H.; Morris, Harold P.; Neilson, Graeme

doi:10.1093/ajcn/34.8.1584

Cited by 16 publications

(6 citation statements)

References 12 publications

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“…This activity is fairly widespread and has been detected in several bacteria, marine organisms, and plants (Fujita, 1954(Fujita, , 1972Murata, 1982). Animals and humans who ingest food containing thiaminase may develop symptoms of thiamin deficiency (Hayashi, 1957;Duffy et al, 1981;Earl et al, 1994;Evans, 1975). Two thiamin-degrading enzymes have been isolated.…”

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confidence: 99%

Mechanistic Studies on Thiaminase I

Costello¹,

Kelleher²,

Abe³

et al. 1996

Journal of Biological Chemistry

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Thiaminase I (EC 2.5.1.2) catalyzes the replacement of the thiazole moiety of thiamin with a wide variety of nucleophiles. Here we report the sequencing of a thiaminase I clone from Bacillus thiaminolyticus, the overexpression of the cloned gene in Escherichia coli, and the purification and characterization of the enzyme. Recombinant thiaminase I functions as a monomer with a Km for thiamin of 3.7 +/- 0.6 microM and a kcat of 34 s-1. Electrospray ionization Fourier-transform mass spectrometry identified a single sequencing error and demonstrated heterogeneity, finding molecular weights of 42,127, 42,198, and 42,255 due to added Ala and Gly-Ala at the amino terminus. Similar analysis of the 4-amino-2-methyl-6-chloropyrimidine inactivated enzyme indicated that the active site nucleophile involved in catalysis of the substitution reaction is located between Pro79 and Thr177. Subsequent cysteine-specific labeling and site-directed mutagenesis identified Cys113 as the active site nucleophile.

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confidence: 99%

Mechanistic Studies on Thiaminase I

Costello¹,

Kelleher²,

Abe³

et al. 1996

Journal of Biological Chemistry

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“…Production of thiaminase by ruminal microorganisms has been suggested to be the cause of certain thiamin deficiencies in livestock (Edwin & Jackson, 1970 AnA 1978). One such organism, Bacillus thiaminolyticus, has also been isolated from the human large intestine (Matsukawa & Misawa, 1949), but the relation of this organism to any human thiamin deficiency or other pathology has not been firmly established (Duffy et al, 1981). Despite interest in this enzyme over a period of 40 years, little is known about its mechanism.…”

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confidence: 99%

Inhibition of thiaminase I from Bacillus thiaminolyticus. Evidence supporting a covalent 1,6-dihydropyrimidinyl-enzyme intermediate

Hutter¹,

Slama²

1987

Biochemistry

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Thiaminase I from Bacillus thiaminolyticus strain Matsukawa et Misawa is completely and irreversibly inhibited by treatment with 4-amino-6-chloro-2-methylpyrimidine. Inhibition is a time-dependent first-order process, exhibiting a half-time of 4 h at an inhibitor concentration of 5 mM. A specific active-site-directed inactivation is supported by protection of the enzymatic activity in the presence of the substrates thiamin and quinoline as well as by the observation that a stoichiometric amount of inorganic chloride is released during inactivation. 4-Amino-5-(anilinomethyl)-6-chloro-2-methylpyrimidine, which resembles the structure of the product of base exchange of thiamin with aniline, inactivates thiaminase approximately 2 orders of magnitude faster. Inactivation is again complete and irreversible and is a time-dependent first-order process, in this case exhibiting saturation at low inhibitor concentrations (KI = 96 microM). Enzyme inactivation can be explained as the result of displacement of chloride from the chloropyrimidine by a nucleophile at the enzyme active site. The inactivation suggests that the Zoltewicz-Kauffman model of bisulfite-catalyzed thiamin cleavage [Zoltewicz, J. A., & Kauffman, G. M. (1977) J. Am. Chem. Soc. 99, 3134-3142], which calls for the reversible nucleophilic addition of catalyst across the 1,6 double bond of thiamin's pyrimidine ring, may be applicable to thiaminase as well.

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“…In general, αETK ≤ 1.15 (≤ 15%) is considered as an indicative of an adequate thiamin status, αETK values 1.15–1.25 (15–25%) as a marker of insufficiency, while αETK > 1.25 (> 25%) is considered as an indicator of thiamin deficiency (IOM, ; WHO, ). These cut‐off values have been applied to assess thiamin status of population groups (Duffy et al., ; Mataix et al., ; Wolters et al., ; Yang et al., ; Shaw et al., ). In eight infants aged 2.5–12 months who had consumed a thiamin free soy‐based formula for some months, αETK were between 13.8% and 37.8% (Fattal‐Valevski et al., ).…”

Section: Definition/categorymentioning

confidence: 99%

Dietary reference values for thiamin

Turck¹,

Bresson²,

Burlingame³

et al. 2016

EFS2

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Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derived dietary reference values (DRVs) for thiamin (vitamin B1). The Panel considers that data from depletion-repletion studies in adults on the amount of dietary thiamin intake associated with the erythrocyte transketolase activity coefficient (aETK) < 1.15, generally considered to reflect an adequate thiamin status, or with the restoration of normal (baseline) erythrocyte transketolase activity, without a sharp increase in urinary thiamin excretion, can be used to estimate thiamin requirement. In the absence of new scientific evidence, the Panel endorses the average requirement (AR) of 0.072 mg/MJ (0.3 mg/1,000 kcal) for all adults proposed by the Scientific Committee for Food (SCF) in 1993 on the basis of one depletion-repletion study, in which both aETK and urinary thiamin excretion were measured. Results from other depletion-repletion studies are in agreement with this value. The Panel agrees on the coefficient of variation of 20% used by the SCF to cover uncertainties related to distribution of thiamin requirements in the general population, and endorses the population reference intake (PRI) of 0.1 mg/MJ (0.4 mg/1,000 kcal) set by the SCF for all adults. The same AR and PRI as for adults, expressed in mg/MJ, are proposed for infants aged 7-11 months, children aged 1 to < 18 years, and during pregnancy and lactation, under the assumption that the relationship between thiamin requirement and energy requirement is the same in all population groups. Acknowledgements: The Panel wishes to thank EFSA member of staff Fanny H eraud for the support provided to this scientific opinion.

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Thiamin status of a Melanesian population

Cited by 16 publications

References 12 publications

Mechanistic Studies on Thiaminase I

Mechanistic Studies on Thiaminase I

Inhibition of thiaminase I from Bacillus thiaminolyticus. Evidence supporting a covalent 1,6-dihydropyrimidinyl-enzyme intermediate

Dietary reference values for thiamin

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