[89] Transketolase: Clinical aspects

Brin, Myron

doi:10.1016/0076-6879(66)09101-8

Cited by 72 publications

(38 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These techniques yielded two practically overlapping patterns consisting of 6 -8 distinct bands within a PI range of 6.5 -8. 5. Both pure and crude transketolase preparations showed a similar heterogeneous profile, thus confirming the stability of the enzyme throughout purification.…”

supporting

confidence: 50%

Transketolase from human leukocytes

Mocali¹,

Paoletti²

1989

European Journal of Biochemistry

View full text Add to dashboard Cite

Transketolase has been purified for the first time from human leukocytes, according to a new procedure which consists of three conventional steps. The enzyme was finally detached from CM-cellulose by specific elution with a ~-xylulose-5-phosphate/~-ribose-5-phosphate mixture and the isolated product exhibited a specific activity of about 10 units/mg protein at 37 "C. Transketolase preparations are contamination-free, except for a slight residual activity of phosphohexose isomerase. Kinetic constants for D-xylulose 5-phosphate and o-ribose 5-phosphate were found to be 0.19 mM and 0.63 mM, respectively. Pure transketolase migrates on SDSjPAGE as a single band, with a molecular mass of about 66 kDa.The isoelectrophoretic heterogeneity of transketolase was assessed either by activity staining or immunovisualization with anti-transketolase antisera, previously induced in rabbits. These techniques yielded two practically overlapping patterns consisting of 6 -8 distinct bands within a PI range of 6.5 -8.5. Both pure and crude transketolase preparations showed a similar heterogeneous profile, thus confirming the stability of the enzyme throughout purification.The occurrence of multiple enzyme forms in fresh human white cells has also been established by the analysis of transketolase in isolated populations of either lymphocytes or polymorphonuclear leukocytes, from individual healthy subjects.Transketolase is a key enzyme of the nonoxidative pentose cycle and catalyzes the reversible transfer of a keto group between several donor and acceptor substrates [l, 21. Both magnesium ions and thiamine pyrophosphate are required as cofactors for enzyme activity [I -41. There is some interest in human transketolase, whose activity in blood cells is used as a marker of thiamine deficiency and poor nutritional status [5, 61. In addition, it has been inferred that transketolase is altered in alcoholics [7] and in patients with WernickeKorsakoff syndrome [8], where the occurrence of peculiar isoenzyme patterns was also reported [9].However, owing to the little information available on pure enzyme preparations, the properties of human transketolase have not yet been clearly established. For instance, the occurrence of multiple forms and variants [lo] Abbreviations. Ery4P, D-erythrose 4-phosphate; XluSP, D-XYIUlose 5-phosphate; RibSP, D-ribose S-phosphate; Glc6P, D-glucose 6-phosphate; Fru6P, D-fructose 6-phosphate; Sed7P, D-sedoheptulose 7-phosphate; DEAE-cellulose, diethylaminoethyl cellulose; CMcellulose, carboxymethyl cellulose; PMN, polymorphonuclear leukocytes; NaCl/Pi buffer, phosphate-buffered saline.Enzymes. Transketolase (EC 2.2.1.1); phosphoribose isomerase (EC 5.3.1.6); D-ribulose-5-phosphate 3-epimerase (EC 5.1.3.1); transaldolase (EC 2.2.1.2); ~-glucose-6-phosphate dehydrogenase (EC 1.1.1.49); hexokinase (EC 2.7.1 .I); glycerol-3-phosphate dehydrogenase (EC 1 1.1.8); phosphohexose isomerase (EC 5.3.1.9).years, all of which concern erythrocytes from outdated blood. We now suggest a new procedure for a high-yield purific...

show abstract

supporting

confidence: 50%

Transketolase from human leukocytes

Mocali¹,

Paoletti²

1989

European Journal of Biochemistry

View full text Add to dashboard Cite

show abstract

“…Erythrocyte transketolase (ETK) activities and liver thiamine content were shown to respond positively to graded but sub-optimal levels of dietary thiamine in thiamine-depleted rats by Ranhotra et al (1985). The relative enhancement of ETK by saturation with thiamine pyrophosphate (TPP) in vitro has been demonstrated to be a sensitive measure for the detection and evaluation of thiamine deficiency in human subjects by severai workers (Brin, 1966;Neumann et al, 1979;Duffy et al, 1981). Neumann et al (1979) showed that TPP effect < 15% indicates normal thiamine nutritional status whereas values> 25% signify thiamine deficiency.…”

Section: Thiamine Repletionmentioning

confidence: 99%

“…Transketolase activity and TPP effect after the addition of TPP (50 J-lg)in the hemolysate (ETK) system were determined according to Brin (1966) and Ranhotra et al (1985). The homogenate was diluted 1:50 with 0.015 molli phosphate assay buffer, pH 7.4.…”

Section: Transketolase Activity and Tpp Effect Determinationmentioning

confidence: 99%

Bioavailability of thiamine in cow milk and curd powders using rat bioassay

Singh

Deodhar

1992

Lait

View full text Add to dashboard Cite

Summary -The biological availability of thiamine (relative to pure thiamine) in cow milk and curd prepared with mixed starter cultures consisting of Lectococcus lactis subsp lactis and cremoris and Propionibacterium shermanii was assessed using thiamine-depleted young rats. The cow milk and curd samples were freeze-dried. Repletion test diets provided 15~g thiamine/d from pasteurized cow milk, curd or pure thiamine for 21 d. Body weight gain, urinary thiamine excretion, hepatic thiamine content, erythrocyte transketolase (ETK) activities with and without added thiamine pyrophosphate (TPP) and TPP effect were determined as the response criteria for this purpose. Twenty-five-d thiamine depletion resulted in a significant (P < 0.01) decrease in body weight gain, decreased thiamine excretion, hepatic thiamine level, ETK activity and increased TPP effect in erythrocyte in comparison to rats receiving standard diet. Repletion with thiamine from different sources brought about a significant (P < 0.01) increase in body weight gain, urinary thiamine excretion, hepatic thiamine and ETK activity. TPP effect for erythrocytes declined significantly (P < 0.01). Restoration was more significant (P < 0.01) in the group receiving curd (CG) than that in the group receiving milk (MG), while it was higher in the MG group than the pure thiamine receiving group (PTG). It was concluded that biological availability of thiamine was greater from curd and milk than from pure thiamine.

show abstract

“…Trehalose was extracted from 60 mg of washed cells (fresh wt) with 2 mL of 0.5 mol L -1 trichloroacetic acid in ice bath for 20 minutes (the suspension was frequently shaken), centrifuged (Trevelyan, 1956a;Trevelyan, 1956b), and 0.2 mL of each supernatant was subjected to anthrone reaction according to BRIN (1966).…”

Section: Yeast Trehalosementioning

confidence: 99%