Which of the following statement about thiamine istrue?
it is co-enzyme for pyruvate dehydrogenase and a-ketoglutarate dehydrogenase Thiamine was the first vitamin to be identified and is therefore called as vitamin B 1. Thiamine has a central role in energy-yielding metabolism and especially the metabolism of carbohydrates. Thiamine pyrophosphate (also k/a thiamine diphosphate) is the biologically active form of the vitamin. Thiamine diphosphate is the coenzyme for: A) 3 multi-enzyme complexes that catalyzes oxidative decarboxylation reactions. - pyruvate dehydrogenase complex (catalyzes oxidative decarboxylation of pyruvate to acetyl-CoA) - a-ketoglutarate dehydrogenase in the citric acid cycle and - branched chain keto-acid dehydrogenase involved in the metabolism of leucine, isoleucine and valine. B) Transketolase, in the pentose phosphate pathway. The oxidative decarboxylation of pyruvate and a-ketoglutarate play a key role in energy metabolism of most cells. In thiamine deficiency, the activity of these two dehydrogenase reactions is decreased, resulting in a decreased production of ATP and thus, impaired cellular. function. Thiamine Deficiency Thiamine deficiency in its early stages causes anorexia, muscle cramps, paraesthesias, and irritability. Prolonged thiamine deficiency causes beriberi, which is classically categorized as wet or dry, though there is considerable overlap. Wet beriberi primarily presents with cardiovascular symptoms characterized by marked peripheral vasodilation resulting in high-output hea failure with dyspnea, tachycardia, cardiomegaly, and pulmonary and peripheral edema, with warm extremities mimicking cellulitis. Dry beriberi presents with a symmetric peripheral neuropathy of the motor and sensory systems with diminished reflexes. The neuropathy affects the legs more than the arms. Alcoholic patients with chronic thiamine deficiency may also have central nervous system manifestations known as Wernicke's encephalopathy.consistinv of horizontal nystagmus, ophthalmoplegia, cerebellar ataxia, and mental impairment. When there is additional loss of memory and a confabulatory psychosis, the syndrome is known as Wernicke-Korsakoff syndrome. The laboratory diagnosis of thiamine deficiency is usually made by enzymatic assay of transketolase activity measured before and after the addition of thiamine pyrophosphate. A more than 25% stimulation of the transketolase activity by the addition of thiamine pyrophosphate is taken as abnormal.
It is a co-enzyme of lactate dehydrogenase
Its deficiency is associated with scurvy
Its co-enzyme function is done by thiamine monophosphate
It is co-enzyme for pyruvate dehydrogenase and a-ketoglutarate dehydrogenase